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Reisig D, Heiniger R. Yield analysis and corn earworm feeding in Bt and non-Bt corn hybrids across diverse locations. JOURNAL OF ECONOMIC ENTOMOLOGY 2024:toae120. [PMID: 38832396 DOI: 10.1093/jee/toae120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 05/01/2024] [Accepted: 05/17/2024] [Indexed: 06/05/2024]
Abstract
Corn, Zea mays L. (Poales: Poaceae), growers in the US Cotton Belt are required to plant 20% of total corn acres to non-Bt hybrids for resistance management (non-Bt refuge). Most growers do not meet this requirement, in part, because they perceive non-Bt hybrids to yield less than Bt hybrids. We planted multiple non-Bt and Bt hybrids from a single company in small-plot replicated trials at a single location from 2019 to 2023, as well as in small-plot replicated trials at multiple locations during 2022 and 2023. In the single location, we measured kernel injury from corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), and we recorded yield at all locations. In the single location trial, yields only separated among hybrids in 3 out of 5 years. In the multiple location trial, yields were variable between both years. We found that Bt hybrids tended to yield higher than non-Bt hybrids overall, but this was influenced by the inclusion of non-Bt hybrids that had a lower overall genetic yield potential in the environments we tested them in. In both tests, when hybrids were analyzed during each year, both Bt and non-Bt hybrids were among the statistically highest yielders. Our study demonstrates the importance of comparing multiple Bt and non-Bt hybrids to draw yield comparisons. This highlights the need for corn seed company breeders to put effort into improving yield for non-Bt hybrids. Hopefully this effort will translate into increased planting of non-Bt refuge corn for growers in the US Cotton Belt.
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Affiliation(s)
- Dominic Reisig
- Department of Entomology and Plant Pathology, NC State University, 207 Research Station Road, Plymouth, NC 27962, USA
| | - Ryan Heiniger
- Department of Crop and Soil Sciences, NC State University, Nelson Hall, 3709 Hillsboro Street, Raleigh, NC 27607, USA
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2
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Pezzini D, Taylor KL, Reisig DD, Fritz ML. Cross-pollination in seed-blended refuge and selection for Vip3A resistance in a lepidopteran pest as detected by genomic monitoring. Proc Natl Acad Sci U S A 2024; 121:e2319838121. [PMID: 38513093 PMCID: PMC10990109 DOI: 10.1073/pnas.2319838121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 12/13/2023] [Indexed: 03/23/2024] Open
Abstract
The evolution of pest resistance to management tools reduces productivity and results in economic losses in agricultural systems. To slow its emergence and spread, monitoring and prevention practices are implemented in resistance management programs. Recent work suggests that genomic approaches can identify signs of emerging resistance to aid in resistance management. Here, we empirically examined the sensitivity of genomic monitoring for resistance management in transgenic Bt crops, a globally important agricultural innovation. Whole genome resequencing of wild North American Helicoverpa zea collected from non-expressing refuge and plants expressing Cry1Ab confirmed that resistance-associated signatures of selection were detectable after a single generation of exposure. Upon demonstrating its sensitivity, we applied genomic monitoring to wild H. zea that survived Vip3A exposure resulting from cross-pollination of refuge plants in seed-blended plots. Refuge seed interplanted with transgenic seed exposed H. zea to sublethal doses of Vip3A protein in corn ears and was associated with allele frequency divergence across the genome. Some of the greatest allele frequency divergence occurred in genomic regions adjacent to a previously described candidate gene for Vip3A resistance. Our work highlights the power of genomic monitoring to sensitively detect heritable changes associated with field exposure to Bt toxins and suggests that seed-blended refuge will likely hasten the evolution of resistance to Vip3A in lepidopteran pests.
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Affiliation(s)
- Daniela Pezzini
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC27513
| | - Katherine L. Taylor
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC27513
- Department of Entomology, University of Maryland, College Park, MD20742
| | - Dominic D. Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC27513
| | - Megan L. Fritz
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC27513
- Department of Entomology, University of Maryland, College Park, MD20742
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3
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Calvin W, Yang F, Kennedy H, Marçon PG, Kerns DL. Susceptibility of Field and Laboratory Bt-Susceptible and Resistant Strains of Helicoverpa zea (Boddie) to HearNPV. PLANTS (BASEL, SWITZERLAND) 2024; 13:529. [PMID: 38498539 PMCID: PMC10892202 DOI: 10.3390/plants13040529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 01/21/2024] [Accepted: 02/05/2024] [Indexed: 03/20/2024]
Abstract
During 2021 and 2022, eight field-collected and five laboratory Helicoverpa zea strains with varying susceptibility to different Bt proteins were evaluated for their responses against HearNPV using diet-overlay bioassays. The five laboratory strains included SS (susceptible to all Bt proteins), CRY-RR (resistant to Cry1 and Cry2), VIP-RR-70 (resistant to Vip3Aa), VIP-RR-15 (resistant to Vip3Aa), and TRE-RR (resistant to Cry1, Cry2, and Vip3Aa). Our findings showed that the susceptibility of TRE-RR, VIP-RR-70, and VIP-RR-15 strains to HearNPV was similar to that of the SS strain. However, the field and Cry-RR strains were more resistant to HearNPV compared to the SS strain. Because most feral H. zea strains in the southern U.S. have developed practical resistance to Cry Bt proteins but remain susceptible to Vip3Aa, the results suggest that the reduced susceptibility to HearNPV in H. zea may be associated with the resistance to Cry Bt proteins but not with the resistance to Vip3Aa. Correlation analysis confirmed that there was a significant positive relationship between Cry resistance and HearNPV resistance, but not between the Vip3Aa resistance and HearNPV resistance in H. zea. Our findings provide valuable insights into the relationship between susceptibility to HearNPV and resistance to Bt proteins in H. zea.
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Affiliation(s)
- Wilfrid Calvin
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
- Department of Entomology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Fei Yang
- Department of Entomology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Haley Kennedy
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
| | | | - David L Kerns
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
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4
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Kerns DD, Yang F, Kerns DL, Stewart SD, Jurat-Fuentes JL. Reduced toxin binding associated with resistance to Vip3Aa in the corn earworm ( Helicoverpa zea). Appl Environ Microbiol 2023; 89:e0164423. [PMID: 38014960 PMCID: PMC10734485 DOI: 10.1128/aem.01644-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 10/17/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE Helicoverpa zea is a major crop pest in the United States that is managed with transgenic corn and cotton that produce insecticidal proteins from the bacterium, Bacillus thuringiensis (Bt). However, H. zea has evolved widespread resistance to the Cry proteins produced in Bt corn and cotton, leaving Vip3Aa as the only plant-incorporated protectant in Bt crops that consistently provides excellent control of H. zea. The benefits provided by Bt crops will be substantially reduced if widespread Vip3Aa resistance develops in H. zea field populations. Therefore, it is important to identify resistance alleles and mechanisms that contribute to Vip3Aa resistance to ensure that informed resistance management strategies are implemented. This study is the first report of reduced binding of Vip3Aa to midgut receptors associated with resistance.
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Affiliation(s)
- Dawson D. Kerns
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, USA
| | - Fei Yang
- Department of Entomology, University of Minnesota, St. Paul, Minnesota, USA
| | - David L. Kerns
- Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - Scott D. Stewart
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, USA
| | - Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, USA
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5
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Kennedy H, Kerns DL, Head GP, Yang F. Cross-resistance and redundant killing of Vip3Aa resistant populations of Helicoverpa zea on purified Bt proteins and pyramided Bt crops. PEST MANAGEMENT SCIENCE 2023; 79:5173-5179. [PMID: 37575031 DOI: 10.1002/ps.7720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/04/2023] [Accepted: 08/14/2023] [Indexed: 08/15/2023]
Abstract
BACKGROUND Pyramiding Bt proteins is a key strategy to delay insect resistance development. However, the durability of pyramided Bt crops for controlling insect pests is threatened by cross-resistance among Bt proteins, which can ultimately contribute to resistance development. The corn earworm, Helicoverpa zea, is a major agricultural pest of pyramided Bt crops. Previous studies have examined cross-resistance and redundant killing of Cry resistance in H. zea, but such information is lacking for Vip3Aa resistance in this pest. Here, we evaluated cross-resistance and redundant killing of Vip3Aa-resistant H. zea to purified Bt proteins, as well as Bt corn and Bt cotton. RESULTS Diet bioassays demonstrated high susceptibility of Vip3Aa-resistant H. zea to Cry1Ac, Cry1A.105, and Cry2Ab2 purified proteins. No Vip3Aa-susceptible, -heterozygous, or -resistant H. zea could survive on pyramided Bt corn containing Cry1 and/or Cry2 proteins. Complete redundant killing was observed in pyramided Bt corn containing Cry1 and/or Cry2 proteins against Vip3Aa resistance in H. zea. Vip3Aa-susceptible, -heterozygous, and -resistant H. zea exhibited survival rates ranging from 0.0% to 22.5% on pyramided Bt cotton with Cry1 and/or Cry2 proteins. Incomplete to complete redundant killing was observed for Vip3Aa-resistant H. zea on pyramided Bt cotton containing Cry1 and/or Cry2 proteins. CONCLUSION Our findings indicate that Vip3Aa-resistant H. zea does not exhibit positive cross-resistance to Cry1 or Cry2 proteins. In addition, most pyramided Bt crops showed complete or nearly complete redundant killing of Vip3Aa-resistant H. zea. These results indicate that a pyramiding strategy would often be effective for managing Vip3Aa resistance in regions of the United States where H. zea has not evolved resistance to Cry1 and Cry2 toxins. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Haley Kennedy
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | | | - Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, USA
- Department of Entomology, University of Minnesota, Saint Paul, MN, USA
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6
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Carrière Y, Degain B, Unnithan GC, Tabashnik BE. Inheritance and fitness cost of laboratory-selected resistance to Vip3Aa in Helicoverpa zea (Lepidoptera: Noctuidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2023; 116:1804-1811. [PMID: 37555261 DOI: 10.1093/jee/toad145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/22/2023] [Accepted: 07/10/2023] [Indexed: 08/10/2023]
Abstract
The polyphagous pest Helicoverpa zea (Lepidoptera: Noctuidae) has evolved practical resistance to transgenic corn and cotton producing Cry1 and Cry2 crystal proteins from Bacillus thuringiensis (Bt) in several regions of the United States. However, the Bt vegetative insecticidal protein Vip3Aa produced by Bt corn and cotton remains effective against this pest. To advance knowledge of resistance to Vip3Aa, we selected a strain of H. zea for resistance to Vip3Aa in the laboratory. After 28 generations of continuous selection, the resistance ratio was 267 for the selected strain (GA-R3) relative to a strain not selected with Vip3Aa (GA). Resistance was autosomal and almost completely recessive at a concentration killing all individuals from GA. Declines in resistance in heterogeneous strains containing a mixture of susceptible and resistant individuals reared in the absence of Vip3Aa indicate a fitness cost was associated with resistance. Previously reported cases of laboratory-selected resistance to Vip3Aa in lepidopteran pests often show partially or completely recessive resistance at high concentrations and fitness costs. Abundant refuges of non-Bt host plants can maximize the benefits of such costs for sustaining the efficacy of Vip3Aa against target pests.
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Affiliation(s)
- Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ, USA
| | - Ben Degain
- Department of Entomology, University of Arizona, Tucson, AZ, USA
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7
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Pezzini DT, Reisig DD, Buntin GD, Del Pozo-Valdivia AI, Gould F, Paula-Moraes SV, Reay-Jones FP. Impact of seed blend and structured maize refuge on Helicoverpa zea (Lepidoptera: Noctuidae) potential phenological resistance development parameters in pupae and adults. PEST MANAGEMENT SCIENCE 2023; 79:3493-3503. [PMID: 37139844 DOI: 10.1002/ps.7529] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 04/29/2023] [Accepted: 05/04/2023] [Indexed: 05/05/2023]
Abstract
BACKGROUND Helicoverpa zea, an economic pest in the south-eastern United States, has evolved practical resistance to Bacillus thuringiensis (Bt) Cry toxins in maize and cotton. Insect resistance management (IRM) programs have historically required planting of structured non-Bt maize, but because of its low adoption, the use of seed blends has been considered. To generate knowledge on target pest biology and ecology to help improve IRM strategies, nine field trials were conducted in 2019 and 2020 in Florida, Georgia, North Carolina, and South Carolina to evaluate the impact of Bt (Cry1Ab + Cry1F or Cry1Ab + Cry1F + Vip3A) and non-Bt maize plants in blended and structured refuge treatments on H. zea pupal survival, weight, soil pupation depth, adult flight parameters, and adult time to eclosion. RESULTS From a very large sample size and geography, we found a significant difference in pupal mortality and weight among treatments in seed blends with Vip3A, implying that cross-pollination occurred between Bt and non-Bt maize ears. There was no treatment effect for pupation depth, adult flight distance, and eclosion time. CONCLUSION Results of this study demonstrate the potential impact of different refuge strategies on phenological development and survival of an important pest species of regulatory concern. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Daniela T Pezzini
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC, USA
| | - G David Buntin
- Department of Entomology, University of Georgia - Griffin Campus, Griffin, GA, USA
| | - Alejandro I Del Pozo-Valdivia
- Department of Entomology, Hampton Roads Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Virginia Beach, VA, USA
| | - Fred Gould
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Silvana V Paula-Moraes
- Entomology and Nematology Department, West Florida Research and Education Center, University of Florida, Jay, FL, USA
| | - Francis Pf Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Florence, SC, USA
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8
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Marques LH, Ishizuka TK, Pereira RR, Istchuk AN, Rossetto J, Moscardini VF, E Silva OANB, Santos AC, Nowatzki T, Dahmer ML, Sethi A, Storer NP, Gontijo PC, Netto JC, Weschenfelder MAG, de Almeida PG, Bernardi O. Performance of cotton expressing Cry1Ac, Cry1F and Vip3Aa19 insecticidal proteins against Helicoverpa armigera, H. zea and their hybrid progeny, and evidence of reduced susceptibility of a field population of H. zea to Cry1 and Vip3Aa in Brazil. PLoS One 2023; 18:e0289003. [PMID: 37490504 PMCID: PMC10368247 DOI: 10.1371/journal.pone.0289003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 07/02/2023] [Indexed: 07/27/2023] Open
Abstract
The genetically modified cotton DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 expressing Cry1Ac, Cry1F and Vip3Aa19 from Bacillus thuringiensis Berliner (Bt) has been cultivated in Brazil since the 2020/2021 season. Here, we assessed the performance of DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton expressing Cry1Ac, Cry1F and Vip3Aa19 against Helicoverpa armigera (Hübner), Helicoverpa zea (Boddie), and their hybrid progeny. We also carried out evaluations with DAS-21023-5 × DAS-24236-5 cotton containing Cry1Ac and Cry1F. In leaf-disk bioassays, DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 was effective in controlling neonates from laboratory colonies of H. armigera, H. zea and the hybrid progeny (71.9%-100% mortality). On floral bud bioassays using L2 larvae, H. zea presented complete mortality, whereas H. armigera and the hybrid progeny showed <55% mortality. On DAS-21023-5 × DAS-24236-5 cotton, the mortality of H. armigera on leaf-disk and floral buds ranged from 60% to 73%, whereas mortality of hybrids was <46%. This Bt cotton caused complete mortality of H. zea larvae from a laboratory colony in the early growth stages, but mortalities were <55% on advanced growth stages and on floral buds. In field studies conducted from 2014 to 2019, DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton was also effective at protecting plants against H. armigera. In contrast, a population of H. zea collected in western Bahia in 2021/2022 on Bt cotton expressing Cry1 and Vip3Aa proteins, showed 63% mortality after 30 d, with insects developing into fifth and sixth instars, on DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton. We conclude that H. armigera, H. zea, and their hybrid progeny can be managed with DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton; however we found the first evidence in Brazil of a significant reduction in the susceptibility to DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton of a population of H. zea collected from Bt cotton in Bahia in 2021/2022.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Mark L Dahmer
- Corteva Agriscience, Johnston, IA, United States of America
| | - Amit Sethi
- Corteva Agriscience, Johnston, IA, United States of America
| | | | - Pablo C Gontijo
- Instituto Federal Goiano (IF Goiano), Campus Rio Verde, Rio Verde, GO, Brazil
| | - Jacob C Netto
- Instituto Mato-grossense do Algodão (IMAmt), Primavera do Leste, MT, Brazil
| | | | | | - Oderlei Bernardi
- Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil
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9
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Huang F, Niu Y, Silva T, Brown S, Towles T, Kerns D, Jurat-Fuentes JL, Head GP, Carroll M, Walker W, Lin S. An Extended Investigation of Unexpected Helicoverpa zea (Boddie) Survival and Ear Injury on a Transgenic Maize Hybrid Expressing Cry1A/Cry2A/Vip3A Toxins. Toxins (Basel) 2023; 15:474. [PMID: 37505743 PMCID: PMC10467152 DOI: 10.3390/toxins15070474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 07/18/2023] [Accepted: 07/20/2023] [Indexed: 07/29/2023] Open
Abstract
The wide occurrence of resistance to Cry1A and Cry2A insecticidal toxins from Bacillus thuringiensis (Bt) in the corn earworm/bollworm Helicoverpa zea (Boddie) leaves the Vip3A toxin produced during the vegetative stage of Bt as the only fully active toxin expressed in transgenic crops to control H. zea in the U.S.A. During 2021, the first unexpected survival of H. zea and injury (UXI) on a maize hybrid expressing Cry1A.105, Cry2Ab2, and Vip3Aa in Louisiana, U.S.A. were observed in two sentinel plots used for resistance monitoring. A follow-up intensive investigation was conducted with two H. zea populations established from larvae collected from the two UXI plots. The main goal of this study was to reveal if the unexpected damage was due to resistance development in the insect to the Bt toxins expressed in the maize hybrid. Diet-overlay bioassays showed that the two populations were highly resistant to Cry1A.105, moderately resistant to Cry2Ab2, but still highly susceptible to Vip3Aa when compared to a reference susceptible strain. In 10 d assays with detached ears, the larvae of the two UXI populations exhibited survival on ears expressing only Cry toxins but presented near 100% mortality on maize hybrids containing both cry and vip3A transgenes. Multiple field trials over three years demonstrated that natural H. zea populations in Louisiana were highly resistant to maize expressing only Cry toxins but remained susceptible to all tested hybrids containing cry and vip3A genes. Altogether, the results of this study suggest that the observed UXIs in Louisiana were associated with a resistance to Cry toxins but were not due to a resistance to Vip3A. The possible causes of the UXIs are discussed. The results generated and procedures adopted in this study help in determining thresholds for defining UXIs, assessing resistance risks, and documenting field resistance.
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Affiliation(s)
- Fangneng Huang
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA; (Y.N.); (T.S.); (S.L.)
| | - Ying Niu
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA; (Y.N.); (T.S.); (S.L.)
| | - Tiago Silva
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA; (Y.N.); (T.S.); (S.L.)
| | - Sebe Brown
- Dean Lee Research & Extension Center, Louisiana State University Agricultural Center, Alexandria, LA 71302, USA; (S.B.); (W.W.)
| | - Tyler Towles
- Macon Ridge Research Station, Louisiana State University Agricultural Center, Winnsboro, LA 71295, USA;
| | - Dawson Kerns
- Department of Entomology & Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA; (D.K.); (J.L.J.-F.)
| | - Juan Luis Jurat-Fuentes
- Department of Entomology & Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA; (D.K.); (J.L.J.-F.)
| | - Graham P. Head
- Bayer Crop Science, St. Louis, MO 63167, USA; (G.P.H.); (M.C.)
| | - Matthew Carroll
- Bayer Crop Science, St. Louis, MO 63167, USA; (G.P.H.); (M.C.)
| | - Wade Walker
- Dean Lee Research & Extension Center, Louisiana State University Agricultural Center, Alexandria, LA 71302, USA; (S.B.); (W.W.)
| | - Shucong Lin
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA; (Y.N.); (T.S.); (S.L.)
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10
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Dively GP, Kuhar TP, Taylor SV, Doughty H, Holmstrom K, Gilrein DO, Nault BA, Ingerson-Mahar J, Huseth A, Reisig D, Fleischer S, Owens D, Tilmon K, Reay-Jones F, Porter P, Smith J, Saguez J, Wells J, Congdon C, Byker H, Jensen B, DiFonzo C, Hutchison WD, Burkness E, Wright R, Crossley M, Darby H, Bilbo T, Seiter N, Krupke C, Abel C, Coates BS, McManus B, Fuller B, Bradshaw J, Peterson JA, Buntin D, Paula-Moraes S, Kesheimer K, Crow W, Gore J, Huang F, Ludwick DC, Raudenbush A, Jimenez S, Carrière Y, Elkner T, Hamby K. Extended Sentinel Monitoring of Helicoverpa zea Resistance to Cry and Vip3Aa Toxins in Bt Sweet Corn: Assessing Changes in Phenotypic and Allele Frequencies of Resistance. INSECTS 2023; 14:577. [PMID: 37504584 PMCID: PMC10380249 DOI: 10.3390/insects14070577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/12/2023] [Accepted: 06/14/2023] [Indexed: 07/29/2023]
Abstract
Transgenic corn and cotton that produce Cry and Vip3Aa toxins derived from Bacillus thuringiensis (Bt) are widely planted in the United States to control lepidopteran pests. The sustainability of these Bt crops is threatened because the corn earworm/bollworm, Helicoverpa zea (Boddie), is evolving a resistance to these toxins. Using Bt sweet corn as a sentinel plant to monitor the evolution of resistance, collaborators established 146 trials in twenty-five states and five Canadian provinces during 2020-2022. The study evaluated overall changes in the phenotypic frequency of resistance (the ratio of larval densities in Bt ears relative to densities in non-Bt ears) in H. zea populations and the range of resistance allele frequencies for Cry1Ab and Vip3Aa. The results revealed a widespread resistance to Cry1Ab, Cry2Ab2, and Cry1A.105 Cry toxins, with higher numbers of larvae surviving in Bt ears than in non-Bt ears at many trial locations. Depending on assumptions about the inheritance of resistance, allele frequencies for Cry1Ab ranged from 0.465 (dominant resistance) to 0.995 (recessive resistance). Although Vip3Aa provided high control efficacy against H. zea, the results show a notable increase in ear damage and a number of surviving older larvae, particularly at southern locations. Assuming recessive resistance, the estimated resistance allele frequencies for Vip3Aa ranged from 0.115 in the Gulf states to 0.032 at more northern locations. These findings indicate that better resistance management practices are urgently needed to sustain efficacy the of corn and cotton that produce Vip3Aa.
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Affiliation(s)
- Galen P Dively
- Department of Entomology, University of Maryland, College Park, MD 20742, USA
| | - Tom P Kuhar
- Department of Entomology, Virginia Tech, Blacksburg, VA 24060, USA
| | - Sally V Taylor
- Department of Entomology, Virginia Tech, Suffolk, VA 23434, USA
| | | | - Kristian Holmstrom
- Pest Management Office, Rutgers University, New Brunswick, NJ 08901, USA
| | | | - Brian A Nault
- Department of Entomology, Cornell AgriTech, Geneva, NY 14456, USA
| | - Joseph Ingerson-Mahar
- Rutgers Agricultural Research and Extension Center, Rutgers University, Bridgeton, NJ 08302, USA
| | - Anders Huseth
- Department of Entomology and Plant Pathology, NC State University, Raleigh, NC 27601, USA
| | - Dominic Reisig
- Department of Entomology and Plant Pathology, NC State University, Plymouth, NC 27962, USA
| | - Shelby Fleischer
- Department of Entomology, Penn State University, University Park, PA 16802, USA
| | - David Owens
- Cooperative Extension, Carvel REC, University of Delaware, Georgetown, DE 19947, USA
| | - Kelley Tilmon
- Ohio Agricultural Research and Development Center, Wooster, OH 44691, USA
| | - Francis Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Florence, SC 29501, USA
| | - Pat Porter
- Department of Entomology, AgriLife Research and Extension Center, Texas A&M University, Lubbock, TX 79401, USA
| | - Jocelyn Smith
- Department of Plant Agriculture, University of Guelph, Ridgetown Campus, ON N1G 2W1, Canada
| | - Julien Saguez
- CEROM, 740 Chemin Trudeau, Saint-Mathieu-de-Beloeil, QC J3G 0E2, Canada
| | - Jason Wells
- New Brunswick Department of Agriculture, Sussex, NB E4E 5L8, Canada
| | - Caitlin Congdon
- Perennia Food and Agriculture, Kentville, NS B4N 1J5, Canada
| | - Holly Byker
- Department of Plant Agriculture, University of Guelph, Winchester, ON N1G 2W1, Canada
| | - Bryan Jensen
- Arlington Agricultural Research Station, University of Wisconsin, WI 53706, USA
| | - Chris DiFonzo
- Department of Entomology, Michigan State University, East Lansing, MI 48824, USA
| | | | - Eric Burkness
- Department of Entomology, University of Minnesota, St. Paul, MN 55455, USA
| | - Robert Wright
- Department of Entomology, University of Nebraska-Lincoln, NE 68588, USA
| | - Michael Crossley
- Department of Entomology and Wildlife Ecology, University of Delaware, Newark, DE 19711, USA
| | - Heather Darby
- Department of Plant and Soil Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Tom Bilbo
- Department of Plant and Environmental Sciences, Clemson University, Charleston, SC 29414, USA
| | - Nicholas Seiter
- Illinois Extension, University of Illinois, Urbana, IL 61820, USA
| | - Christian Krupke
- Department of Entomology, Purdue University, West Lafayette, IN 47906, USA
| | - Craig Abel
- USDA-ARS Corn Insects and Crop Genetics Research, Iowa State University, Ames, IA 50011, USA
| | - Brad S Coates
- USDA-ARS Corn Insects and Crop Genetics Research, Iowa State University, Ames, IA 50011, USA
| | | | | | - Jeffrey Bradshaw
- Panhandle Research and Extension Center, Scottsbluff, NE 69361, USA
| | - Julie A Peterson
- West Central Research and Extension Center, University of Nebraska, North Platte, NE 69101, USA
| | - David Buntin
- Griffin Campus, University of Georgia, Griffin, GA 30223, USA
| | | | - Katelyn Kesheimer
- Department of Entomology & Plant Pathology, Auburn University, Auburn, AL 36849, USA
| | - Whitney Crow
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Delta Research and Extension Center, Mississippi State University, Stoneville, MS 39762, USA
| | - Jeffrey Gore
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Delta Research and Extension Center, Mississippi State University, Stoneville, MS 39762, USA
| | - Fangneng Huang
- Department of Entomology, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Dalton C Ludwick
- Department of Entomology, Texas A&M AgriLife Extension Service, Corpus Christi, TX 78404, USA
| | - Amy Raudenbush
- Ohio Agricultural Research and Development Center, Wooster, OH 44691, USA
| | - Sebastian Jimenez
- PEI Department of Agriculture and Land, Charlotte, PE C1A 7N8, Canada
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA
| | - Timothy Elkner
- Southeast Research and Extension Center, Landisville, PA 17538, USA
| | - Kelly Hamby
- Department of Entomology, University of Maryland, College Park, MD 20742, USA
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11
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Guan F, Dai X, Hou B, Wu S, Yang Y, Lu Y, Wu K, Tabashnik BE, Wu Y. Refuges of conventional host plants counter dominant resistance of cotton bollworm to transgenic Bt cotton. iScience 2023; 26:106768. [PMID: 37216101 PMCID: PMC10196555 DOI: 10.1016/j.isci.2023.106768] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 03/08/2023] [Accepted: 04/24/2023] [Indexed: 05/24/2023] Open
Abstract
Transgenic crops have revolutionized insect pest control, but evolution of resistance by pests threatens their continued success. The primary strategy for combating pest resistance to crops producing insecticidal proteins from Bacillus thuringiensis (Bt) uses refuges of non-Bt host plants to allow survival of susceptible insects. The prevailing paradigm is that refuges delay resistance that is rare and recessively inherited. However, we discovered refuges countered resistance to Bt cotton that was neither rare nor recessive. In a 15-year field study of the cotton bollworm, the frequency of a mutation conferring dominant resistance to Bt cotton surged 100-fold from 2006 to 2016 yet did not rise from 2016 to 2020. Computer simulations indicate the increased refuge percentage from 2016 to 2020 is sufficient to explain the observed halt in the evolution of resistance. The results also demonstrate the efficacy of a Bt crop can be sustained by non-Bt refuges of other crops.
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Affiliation(s)
- Fang Guan
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Xiaoguang Dai
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Bofeng Hou
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Shuwen Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Yihua Yang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Yanhui Lu
- Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Kongming Wu
- Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | | | - Yidong Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
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12
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Tabashnik BE, Fabrick JA, Carrière Y. Global Patterns of Insect Resistance to Transgenic Bt Crops: The First 25 Years. JOURNAL OF ECONOMIC ENTOMOLOGY 2023; 116:297-309. [PMID: 36610076 DOI: 10.1093/jee/toac183] [Citation(s) in RCA: 35] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Indexed: 05/29/2023]
Abstract
Crops genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have improved pest management and reduced reliance on insecticide sprays. However, evolution of practical resistance by some pests has reduced the efficacy of Bt crops. We analyzed global resistance monitoring data for 24 pest species based on the first 25 yr of cultivation of Bt crops including corn, cotton, soybean, and sugarcane. Each of the 73 cases examined represents the response of one pest species in one country to one Bt toxin produced by one or more Bt crops. The cases of practical resistance rose from 3 in 2005 to 26 in 2020. Practical resistance has been documented in some populations of 11 pest species (nine lepidopterans and two coleopterans), collectively affecting nine widely used crystalline (Cry) Bt toxins in seven countries. Conversely, 30 cases reflect no decrease in susceptibility to Bt crops in populations of 16 pest species in 10 countries. The remaining 17 cases provide early warnings of resistance, which entail genetically based decreases in susceptibility without evidence of reduced field efficacy. The early warnings involve four Cry toxins and the Bt vegetative insecticidal protein Vip3Aa. Factors expected to favor sustained susceptibility include abundant refuges of non-Bt host plants, recessive inheritance of resistance, low resistance allele frequency, fitness costs, incomplete resistance, and redundant killing by multi-toxin Bt crops. Also, sufficiently abundant refuges can overcome some unfavorable conditions for other factors. These insights may help to increase the sustainability of current and future transgenic insecticidal crops.
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Affiliation(s)
| | - Jeffrey A Fabrick
- USDA ARS, U. S. Arid Land Agricultural Research Center, Maricopa, AZ, USA
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ, USA
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13
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Santiago-González JC, Kerns DL, Head GP, Yang F. A Modified F2 Screen for Estimating Cry1Ac and Cry2Ab Resistance Allele Frequencies in Helicoverpa zea (Lepidoptera: Noctuidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2023; 116:289-296. [PMID: 36610074 DOI: 10.1093/jee/toac181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Indexed: 05/30/2023]
Abstract
Evaluating the frequency of resistance alleles is important for resistance management and sustainable use of transgenic crops that produce insecticidal proteins from Bacillus thuringiensis. Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) is a major crop pest in the United States that has evolved practical resistance to the crystalline (Cry) proteins in Bt corn and cotton. The standard F2 screen for estimating resistance allele frequency does not work well for H. zea because successful single-pair matings are rare. In this study, we developed and implemented a modified F2 screen for H. zea that generates F1 progeny by crossing three laboratory susceptible female moths with one feral male moth instead of single-pair crosses. During 2019-2020, we used this modified method to establish 192 F2 families from 623 matings between susceptible females and feral males from Arkansas, Louisiana, Mississippi, and Tennessee. From each F2 family, we screened 128 neonates against discriminating concentrations of Cry1Ac and Cry2Ab in diet overlay bioassays. Based on these discriminating concentration bioassays, families were considered positive for resistance if at least five larvae survived to second instar, including at least one to third instar. The percentage of positive families was 92.7% for Cry1Ac and 38.5% for Cry2Ab, which yields an estimated resistance allele frequency (with 95% confidence interval) of 0.722 (0.688-0.764) for Cry1Ac and 0.217 (0.179-0.261) for Cry2Ab. The modified F2 screen developed and implemented here may be useful for future resistance monitoring studies of H. zea and other pests.
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Affiliation(s)
| | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | | | - Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, USA
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14
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dos Santos IB, Paula-Moraes SV, Beuzelin JM, Hahn DA, Perera OP, Fraisse C. Factors Affecting Population Dynamics of Helicoverpa zea (Lepidoptera: Noctuidae) in a Mixed Landscape with Bt Cotton and Peanut. INSECTS 2023; 14:395. [PMID: 37103210 PMCID: PMC10142863 DOI: 10.3390/insects14040395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/14/2023] [Accepted: 04/15/2023] [Indexed: 06/19/2023]
Abstract
In North America, weather and host-plant abundance drive the population dynamics of the migratory pest Helicoverpa zea. The objectives of this study were to (i) estimate monthly abundance of H. zea moths in Bt cotton and peanut fields, (ii) document the effects of weather on H. zea trap catches, and (iii) determine larval hosts supporting H. zea populations from 2017 to 2019. Year-round trapping of H. zea moths was conducted in 16 commercial fields in two regions of the Florida Panhandle using delta traps. H. zea moth catches were associated with temperature, rainfall, and relative humidity. Larval hosts were determined by isotopic carbon analysis. Our results showed year-round H. zea flights in both regions across two years, with the highest and lowest moth catches occurring from July to September and November to March, respectively. There was no difference in catches between traps set on Bt cotton and peanut. In the Santa Rosa/Escambia counties, weather explained 59% of the variance in H. zea catches, with significant effects of temperature, relative humidity, and rainfall. In Jackson County, weather explained 38% of H. zea catches, with significant effects of temperature and relative humidity. Carbon isotopic data showed that feeding on C3 plants, including Bt cotton, occurred over most of the year, although feeding on C4 hosts, including Bt corn, occurred during the summer months. Hence overwintering and resident populations of H. zea in the Florida Panhandle may be continually exposed to Bt crops, increasing the risk for the evolution of resistance.
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Affiliation(s)
- Izailda Barbosa dos Santos
- West Florida Research and Education Center, Department of Entomology and Nematology, University of Florida, Jay, FL 32565, USA
| | - Silvana V. Paula-Moraes
- West Florida Research and Education Center, Department of Entomology and Nematology, University of Florida, Jay, FL 32565, USA
| | - Julien M. Beuzelin
- Everglades Research and Education Center, Department of Entomology and Nematology, University of Florida, 3200 East Palm Beach Road, Belle Glade, FL 33430, USA
| | - Daniel A. Hahn
- Department of Entomology and Nematology, University of Florida, 1881 Natural Area Drive, Gainesville, FL 32611, USA
| | | | - Clyde Fraisse
- Department of Agricultural and Biological Engineering, University of Florida, 271 Frazier Rogers Hall, Gainesville, FL 32611, USA
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15
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Reisig D, Buntin GD, Greene JK, Paula-Moraes SV, Reay-Jones F, Roberts P, Smith R, Taylor SV. Magnitude and Extent of Helicoverpa zea Resistance Levels to Cry1Ac and Cry2Ab2 across the Southeastern USA. INSECTS 2023; 14:262. [PMID: 36975947 PMCID: PMC10058025 DOI: 10.3390/insects14030262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/27/2023] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
After resistance is first detected, continued resistance monitoring can inform decisions on how to effectively manage resistant populations. We monitored for resistance to Cry1Ac (2018 and 2019) and Cry2Ab2 (2019) from southeastern USA populations of Helicoverpa zea. We collected larvae from various plant hosts, sib-mated the adults, and tested neonates using diet-overlay bioassays and compared them to susceptible populations for resistance estimates. We also compared LC50 values with larval survival, weight and larval inhibition at the highest dose tested using regression, and found that LC50 values were negatively correlated with survival for both proteins. Finally, we compared resistance rations between Cry1Ac and Cry2Ab2 during 2019. Some populations were resistant to Cry1Ac, and most were resistant to CryAb2; Cry1Ac resistance ratios were lower than Cry2Ab2 during 2019. Survival was positively correlated with larval weight inhibition for Cry2Ab. This contrasts with other studies in both the mid-southern and southeastern USA, where resistance to Cry1Ac, Cry1A.105, and Cry2Ab2 increased over time and was found in a majority of populations. This indicates that cotton expressing Cry proteins in the southeastern USA was at variable risk for damage in this region.
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Affiliation(s)
- Dominic Reisig
- Department of Entomology, The Vernon James Center, North Carolina State University, Plymouth, NC 27962, USA
| | - G. David Buntin
- Department of Entomology, University of Georgia, Tifton, GA 31793, USA
| | - Jeremy K. Greene
- Department of Plant and Environmental Sciences, Clemson University, Blackville, SC 29817, USA
| | | | - Francis Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Blackville, SC 29817, USA
| | - Phillip Roberts
- Department of Entomology, University of Georgia, Tifton, GA 31793, USA
| | - Ron Smith
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA
| | - Sally V. Taylor
- Department of Entomology, Virginia Polytechnic Institute and State University, Suffolk, VA 23437, USA
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16
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Dillard D, Reisig DD, Reay-Jones FPF. Helicoverpa zea (Lepidoptera: Noctuidae) In-Season and Overwintering Pupation Response to Soil Type. ENVIRONMENTAL ENTOMOLOGY 2023; 52:67-73. [PMID: 36541241 DOI: 10.1093/ee/nvac106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Indexed: 06/17/2023]
Abstract
Heliothinae soil pupation is understudied despite the key role this life stage plays in their development. Many Heliothinae are important agricultural pests and understanding the interplay of environment and pupation is important to optimize pest management tactics oriented toward pupae. We studied the impact of three soil types (coarse sand, high organic muck, and fine-textured clay) on Helicoverpa zea (Boddie) in-season and overwintering pupal survivorship, diapause, depth, and weight in at two locations (North and South Carolina). We introduced wild-collected (in-season) and laboratory-reared (over the winter) infestations of H. zea larvae to each of the three soils and later excavated pupae. In-season and over the winter pupal survivorship was lower in fine-textured clay soils than in coarse sand or high organic muck. In addition, pupal depth and weight, in-season and over the winter, varied significantly by soil type. In general, depth was the shallowest, and pupae weight was lower when recovered from fine-textured clay soils. Finally, diapausing characteristics varied significantly by location and year, likely impacted by differing environmental conditions. Our results suggest that fine-textured clay soils negatively impact Heliothinae pupation and may be suppressing populations in areas with these soil types.
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Affiliation(s)
- DeShae Dillard
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, 207 Research Station Road, Plymouth, NC, 27962, USA
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, 207 Research Station Road, Plymouth, NC, 27962, USA
| | - Francis P F Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, 2200 Pocket Road, Florence, SC, 29506, USA
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17
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Santiago-González JC, Kerns DL, Yang F. Resistance Allele Frequency of Helicoverpa zea to Vip3Aa Bacillus thuringiensis Protein in the Southeastern U.S. INSECTS 2023; 14:161. [PMID: 36835730 PMCID: PMC9958976 DOI: 10.3390/insects14020161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/23/2023] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
Helicoverpa zea is a major target pest of Bt crops expressing Cry and/or Vip3Aa proteins in the U.S.A. Widespread practical resistance of H. zea to the Cry1 and Cry2 proteins makes Vip3Aa the only effective Bt protein against this pest. Understanding the frequency of resistance alleles against Vip3Aa in field populations of H. zea is crucial for resistance management and the sustainability of Vip3Aa technology. Using a modified F2 screen method by crossing susceptible laboratory female moth with feral male moth of H. zea, we successfully screened a total of 24,576 neonates from 192 F2 families of H. zea collected from Arkansas, Louisiana, Mississippi, and Tennessee during 2019-2020. We found five F2 families containing ≥3rd instar survivors on the diagnostic concentration of 3.0 µg/cm2 Vip3Aa39. Dose-response bioassays confirmed the high levels of Vip3Aa resistance in these F2 families, with an estimated resistance ratio of >909.1-fold relative to the susceptible strain. The estimated resistance allele frequency against Vip3Aa in H. zea for these four southern states is 0.0155 with a 95% CI of 0.0057-0.0297. These data should provide critical information for understanding the risks of Vip3Aa resistance in H. zea and help design appropriate resistance management strategies for the sustainability of the Vip3Aa technology.
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18
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Gassmann AJ, Reisig DD. Management of Insect Pests with Bt Crops in the United States. ANNUAL REVIEW OF ENTOMOLOGY 2023; 68:31-49. [PMID: 36170641 DOI: 10.1146/annurev-ento-120220-105502] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Genetically engineered corn and cotton that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) have been used to manage insect pests in the United States and elsewhere. In some cases, this has led to regional suppression of pest populations and pest eradication within the United States, and these outcomes were associated with reductions in conventional insecticides and increased profits for farmers. In other instances, pests evolved resistance to multiple Bt traits, compromising the capacity of Bt crops to manage pests and leading to increased feeding injury to crops in the field. Several aspects of pest biology and pest-crop interactions were associated with cases where pests remained susceptible versus instances where pests evolved resistance. The viability of future transgenic traits can be improved by learning from these past outcomes. In particular, efforts should be made to delay resistance by increasing the prevalence of refuges and using integrated pest management.
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Affiliation(s)
- Aaron J Gassmann
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, Iowa, USA;
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Plymouth, North Carolina, USA
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19
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Yang F, Kerns DL, Little N, Brown SA, Stewart SD, Catchot AL, Cook DR, Gore J, Crow WD, Lorenz GM, Towles T, Tabashnik BE. Practical resistance to Cry toxins and efficacy of Vip3Aa in Bt cotton against Helicoverpa zea. PEST MANAGEMENT SCIENCE 2022; 78:5234-5242. [PMID: 36053801 DOI: 10.1002/ps.7142] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 08/14/2022] [Accepted: 08/23/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Crops genetically engineered to make insect-killing proteins from Bacillus thuringiensis (Bt) have revolutionized management of some pests. However, the benefits of such transgenic crops are reduced when pests evolve resistance to Bt toxins. We evaluated resistance to Bt toxins and Bt cotton plants using laboratory bioassays and complementary field trials focusing on Helicoverpa zea, one of the most economically important pests of cotton and other crops in the United States. RESULTS The data from 235 laboratory bioassays demonstrate resistance to Cry1Ac, Cry1Fa, and Cry2Ab occurred in most of the 95 strains of H. zea derived from Arkansas, Louisiana, Mississippi, Tennessee, and Texas during 2016 to 2021. Complementary field data show efficacy decreased for Bt cotton producing Cry1Ac + Cry1Fa or Cry1Ac + Cry2Ab, but not Cry1Ac + Cry1Fa + Vip3Aa. Moreover, analysis of data paired by field site and year shows higher survival in bioassays was generally associated with lower efficacy of Bt cotton. CONCLUSIONS The results confirm and extend previous evidence showing widespread practical resistance of H. zea in the United States to the Cry toxins produced by Bt cotton and corn, but not to Vip3Aa. Despite deployment in combination with Cry toxins in Bt crops, Vip3Aa effectively acts as a single toxin against H. zea larvae that are highly resistant to Cry toxins. Furthermore, Vip3Aa adoption is increasing and previous work provided an early warning of field-evolved resistance. Thus, rigorous resistance management measures are needed to preserve the efficacy of Vip3Aa against this highly adaptable pest. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Nathan Little
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, MS, USA
| | - Sebe A Brown
- Department of Entomology and Plant Pathology, University of Tennessee, Jackson, TN, USA
| | - Scott D Stewart
- Department of Entomology and Plant Pathology, University of Tennessee, Jackson, TN, USA
| | - Angus L Catchot
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, USA
| | - Donald R Cook
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, USA
| | - Jeffrey Gore
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, USA
| | - Whitney D Crow
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, USA
| | - Gustav M Lorenz
- Department of Entomology and Plant Pathology, University of Arkansas, Lonoke, AR, USA
| | - Tyler Towles
- Department of Entomology, Louisiana State University, Winnsboro, LA, USA
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20
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Fabrick JA, Heu CC, LeRoy DM, DeGain BA, Yelich AJ, Unnithan GC, Wu Y, Li X, Carrière Y, Tabashnik BE. Knockout of ABC transporter gene ABCA2 confers resistance to Bt toxin Cry2Ab in Helicoverpa zea. Sci Rep 2022; 12:16706. [PMID: 36202979 PMCID: PMC9537329 DOI: 10.1038/s41598-022-21061-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 09/22/2022] [Indexed: 11/08/2022] Open
Abstract
Evolution of pest resistance reduces the benefits of widely cultivated genetically engineered crops that produce insecticidal proteins derived from Bacillus thuringiensis (Bt). Better understanding of the genetic basis of pest resistance to Bt crops is needed to monitor, manage, and counter resistance. Previous work shows that in several lepidopterans, resistance to Bt toxin Cry2Ab is associated with mutations in the gene encoding the ATP-binding cassette protein ABCA2. The results here show that mutations introduced by CRISPR/Cas9 gene editing in the Helicoverpa zea (corn earworm or bollworm) gene encoding ABCA2 (HzABCA2) can cause resistance to Cry2Ab. Disruptive mutations in HzABCA2 facilitated the creation of two Cry2Ab-resistant strains. A multiple concentration bioassay with one of these strains revealed it had > 200-fold resistance to Cry2Ab relative to its parental susceptible strain. All Cry2Ab-resistant individuals tested had disruptive mutations in HzABCA2. We identified five disruptive mutations in HzABCA2 gDNA. The most common mutation was a 4-bp deletion in the expected Cas9 guide RNA target site. The results here indicate that HzABCA2 is a leading candidate for monitoring Cry2Ab resistance in field populations of H. zea.
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Affiliation(s)
- Jeffrey A Fabrick
- USDA ARS, U.S. Arid Land Agricultural Research Center, 21881 N. Cardon Lane, Maricopa, AZ, 85138, USA.
| | - Chan C Heu
- USDA ARS, U.S. Arid Land Agricultural Research Center, 21881 N. Cardon Lane, Maricopa, AZ, 85138, USA
| | - Dannialle M LeRoy
- USDA ARS, U.S. Arid Land Agricultural Research Center, 21881 N. Cardon Lane, Maricopa, AZ, 85138, USA
| | - Ben A DeGain
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
| | - Alex J Yelich
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
| | | | - Yidong Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xianchun Li
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
| | - Bruce E Tabashnik
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
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21
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Santiago-González JC, Kerns DL, Head GP, Yang F. Effective dominance and redundant killing of single- and dual-gene resistant populations of Helicoverpa zea on pyramided Bt corn and cotton. PEST MANAGEMENT SCIENCE 2022; 78:4333-4339. [PMID: 35750998 DOI: 10.1002/ps.7052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/13/2022] [Accepted: 06/24/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Pyramided Bacillus thuringiensis (Bt) crops producing multiple Bt proteins with different modes of action are widely planted in the United States. Helicoverpa zea is a major target pest of pyramided Bt crops and has evolved practical resistance to both Cry1 and Cry2 proteins in some regions of U.S. However, little information is available regarding redundant killing and the dominance of resistance for insects possessing multiple resistance on pyramided Bt crops. In this study, we evaluated redundant killing and the dominance of resistance for H. zea strains resistant to Cry1 or Cry1 + Cry2 on pyramided Bt corn and cotton. RESULTS We found that the Cry1-resistant H. zea was incompletely dominant on Cry1Ac + Cry1F cotton. Pyramided crops producing Cry2 and/or Vip3Aa proteins showed a complete redundant killing against the Cry1-resistant H. zea. The Cry1 + Cry2-resistant H. zea displayed incompletely recessive to completely dominant resistance on pyramided Bt crops containing Cry1 and/or Cry2 proteins. The redundant killing was complete for the Cry1 + Cry2-resistant H. zea on pyramided Bt crops producing Vip3Aa protein. CONCLUSION The dominant resistance of Cry1 and Cry2 in H. zea on pyramided Bt crops deviates from the assumption of functionally recessive resistance underlying the high-dose refuge strategy. However, the assumptions of complete redundant killing are achieved for both Cry1- and Cry1 + Cry2-resistant H. zea on pyramided Bt crops. These results suggest that the pyramided strategy could be valuable for increasing the durability of Bt technology for managing H. zea, a pest with inherently low susceptibility against Cry proteins. © 2022 Society of Chemical Industry.
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Affiliation(s)
| | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | | | - Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, USA
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Yu W, Head GP, Huang F. Inheritance of Resistance to Cry1A.105 in Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae). INSECTS 2022; 13:875. [PMID: 36292823 PMCID: PMC9604160 DOI: 10.3390/insects13100875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 09/20/2022] [Accepted: 09/23/2022] [Indexed: 06/16/2023]
Abstract
Cry1A.105 is a bioengineered Bacillus thuringiensis (Bt) insecticidal protein consisting of three domains derived from Cry1Ac, Cry1Ab, and Cry1F. It is one of the two pyramided Bt toxins expressed in the MON 89034 event, a commonly planted Bt maize trait in the Americas. Recent studies have documented that field resistance of the corn earworm, Helicoverpa zea (Boddie), to the Cry1A.105 toxin in maize plants has become widespread in the United States. To investigate the inheritance of resistance to Cry1A.105 in H. zea, two independent tests, each with various genetic crosses among susceptible and Cry1A.105-resistant populations, were performed. The responses of these susceptible, resistant, F1, F2, and backcrossed insect populations to Cry1A.105 were assayed using a diet overlay method. The bioassays showed that the resistance to Cry1A.105 in H. zea was inherited as a single, autosomal, nonrecessive gene. The nonrecessive nature of the resistance could be an important factor contributing to the widespread resistance of maize hybrids containing Cry1A.105 in the United States. The results indicate that resistance management strategies for Bt crops need to be refined to ensure that they are effective in delaying resistance evolution for nonrecessive resistance (nonhigh dose).
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Affiliation(s)
- Wenbo Yu
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA
| | | | - Fangneng Huang
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA
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Pest population dynamics are related to a continental overwintering gradient. Proc Natl Acad Sci U S A 2022; 119:e2203230119. [PMID: 36067290 PMCID: PMC9477387 DOI: 10.1073/pnas.2203230119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Overwintering success is an important determinant of arthropod populations that must be considered as climate change continues to influence the spatiotemporal population dynamics of agricultural pests. Using a long-term monitoring database and biologically relevant overwintering zones, we modeled the annual and seasonal population dynamics of a common pest, Helicoverpa zea (Boddie), based on three overwintering suitability zones throughout North America using four decades of soil temperatures: the southern range (able to persist through winter), transitional zone (uncertain overwintering survivorship), and northern limits (unable to survive winter). Our model indicates H. zea population dynamics are hierarchically structured with continental-level effects that are partitioned into three geographic zones. Seasonal populations were initially detected in the southern range, where they experienced multiple large population peaks. All three zones experienced a final peak between late July (southern range) and mid-August to mid-September (transitional zone and northern limits). The southern range expanded by 3% since 1981 and is projected to increase by twofold by 2099 but the areas of other zones are expected to decrease in the future. These changes suggest larger populations may persist at higher latitudes in the future due to reduced low-temperature lethal events during winter. Because H. zea is a highly migratory pest, predicting when populations accumulate in one region can inform synchronous or lagged population development in other regions. We show the value of combining long-term datasets, remotely sensed data, and laboratory findings to inform forecasting of insect pests.
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Yang F, Kennedy H, Santiago-González JC, Kerns DL. Effects of cross-pollination among non-Bt and pyramided Bt corn expressing cry proteins in seed mixtures on resistance development of dual-gene resistant Helicoverpa zea. PEST MANAGEMENT SCIENCE 2022; 78:3260-3265. [PMID: 35474413 DOI: 10.1002/ps.6945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 04/14/2022] [Accepted: 04/26/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Seed mixture strategy can guarantee the compliance of planting non-Bt crops to host the susceptible insects for resistance management. However, pollen movement between Bt and non-Bt corn in the mixed plantings could reduce the efficacy of this strategy for ear-feeding insects. Few studies have evaluated the effects of cross-pollination among non-Bt and pyramided Bt corn in seed mixtures on the resistance development of insects possessing multiple resistances. Here, we provided the first study to investigate whether cross-pollination in mixed plantings of pyramided Bt corn producing Cry1A.105 and Cry2Ab2 would increase the dominance of resistance of dual-gene resistant populations of Helicoverpa zea, a target of pyramided Bt corn and cotton in the USA. RESULTS We compared the survival and development of susceptible, dual-gene resistant (resistance to both Cry1 and Cry2 proteins) and heterozygous genotypes of H. zea in the laboratory on non-Bt and pyramided Bt corn ears collected from mixed plantings and structured plantings in the field. We found higher fitness for F1 heterozygous insects than for the susceptible insects of H. zea on both pyramided Bt corn and non-Bt corn in the mixed plantings. CONCLUSION These results suggest that cross-pollination in mixed plantings will significantly increase the dominance of resistance by supporting survival of heterozygous insects for dual-gene resistant populations of H. zea, and therefore accelerate evolution of resistance to pyramided Bt crops. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Fei Yang
- Department of Entomology, Texas A&M University, College Station, Texas, 77843-2475, USA
| | - Haley Kennedy
- Department of Entomology, Texas A&M University, College Station, Texas, 77843-2475, USA
| | | | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, Texas, 77843-2475, USA
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Benowitz KM, Allan CW, Degain BA, Li X, Fabrick JA, Tabashnik BE, Carrière Y, Matzkin LM. Novel genetic basis of resistance to Bt toxin Cry1Ac in Helicoverpa zea. Genetics 2022; 221:6540856. [PMID: 35234875 PMCID: PMC9071530 DOI: 10.1093/genetics/iyac037] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 02/25/2022] [Indexed: 11/14/2022] Open
Abstract
Crops genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis have advanced pest management, but their benefits are diminished when pests evolve resistance. Elucidating the genetic basis of pest resistance to Bacillus thuringiensis toxins can improve resistance monitoring, resistance management, and the design of new insecticides. Here, we investigated the genetic basis of resistance to Bacillus thuringiensis toxin Cry1Ac in the lepidopteran Helicoverpa zea, one of the most damaging crop pests in the United States. To facilitate this research, we built the first chromosome-level genome assembly for this species, which has 31 chromosomes containing 375 Mb and 15,482 predicted proteins. Using a genome-wide association study, fine-scale mapping, and RNA-seq, we identified a 250-kb quantitative trait locus on chromosome 13 that was strongly associated with resistance in a strain of Helicoverpa zea that had been selected for resistance in the field and lab. The mutation in this quantitative trait locus contributed to but was not sufficient for resistance, which implies alleles in more than one gene contributed to resistance. This quantitative trait locus contains no genes with a previously reported role in resistance or susceptibility to Bacillus thuringiensis toxins. However, in resistant insects, this quantitative trait locus has a premature stop codon in a kinesin gene, which is a primary candidate as a mutation contributing to resistance. We found no changes in gene sequence or expression consistently associated with resistance for 11 genes previously implicated in lepidopteran resistance to Cry1Ac. Thus, the results reveal a novel and polygenic basis of resistance.
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Affiliation(s)
- Kyle M Benowitz
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA,Department of Biology, Austin Peay State University, Clarksville, TN 37040, USA,Corresponding author: Department of Biology, Austin Peay State University, Sundquist Science Center, 681 Summer St., Clarksville, TN 37040, USA.
| | - Carson W Allan
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA
| | - Benjamin A Degain
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA
| | - Xianchun Li
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA
| | - Jeffrey A Fabrick
- U.S. Department of Agriculture, Agricultural Research Service, U.S. Arid Land Agricultural Research Center, Maricopa, AZ 85138, USA
| | - Bruce E Tabashnik
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA
| | - Luciano M Matzkin
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA,Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA,Bio5 Institute, University of Arizona, Tucson, AZ 85721, USA
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26
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Godbold RE, Crow WD, Catchot AL, Gore J, Cook DR, Dodds DM, Musser FM, Little NS. Feeding Behavior and Fruiting Form Damage by Bollworm (Lepidoptera: Noctuidae) in Bt Cotton. JOURNAL OF ECONOMIC ENTOMOLOGY 2022; 115:160-167. [PMID: 34791314 DOI: 10.1093/jee/toab220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Indexed: 06/13/2023]
Abstract
Bt technologies have played a major role in the control of bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), in cotton. Variation in expression levels among varieties and plant parts, along with selection pressure on bollworm populations, has led to the development of resistance to some Bt proteins. Trials were conducted to evaluate how cotton varieties expressing different Bt proteins affect bollworm larval behavior and their damage in flowering cotton. Differences in larval recovery were observed among cotton varieties at 3 d with 3-gene Bt cotton having the lowest recovery and non-Bt cotton having the greatest recovery. Loss of bloom tags and abscission of small bolls at the site of infestation affected bollworm larval recovery among varieties. Day after infestation was the main factor that affected bollworm movement across all varieties. Number of total damaged fruiting forms by an individual bollworm larva was different among all varieties. Overall, flower bud (square) and fruit (boll) damage by an individual larva was lower on 3-gene cotton than 2-gene cotton and non-Bt cotton. An individual larva damaged fewer squares on 2-gene cotton than non-Bt cotton, but boll damage from bollworm was similar among 2-gene cotton and non-Bt cotton. The level of square and boll damage in 2-gene cotton has increased compared to previous research further supporting the occurrence of bollworm resistance to Cry proteins. The 3-gene cotton containing the Vip3A gene experienced low levels of damage and survival. These results will be important for improving management recommendations of bollworm in Bt cotton technologies.
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Affiliation(s)
- R E Godbold
- Mississippi State University, Delta Research and Extension Center, P.O. Box 197, Stoneville, MS 38776, USA
| | - W D Crow
- Mississippi State University, Delta Research and Extension Center, P.O. Box 197, Stoneville, MS 38776, USA
| | - A L Catchot
- Mississippi State University, Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State, MS 39762, USA
| | - J Gore
- Mississippi State University, Delta Research and Extension Center, P.O. Box 197, Stoneville, MS 38776, USA
| | - D R Cook
- Mississippi State University, Delta Research and Extension Center, P.O. Box 197, Stoneville, MS 38776, USA
| | - D M Dodds
- Mississippi State University, Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State, MS 39762, USA
| | - F M Musser
- Mississippi State University, Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State, MS 39762, USA
| | - N S Little
- USDA-ARS, Southern Insect Management Research Unit, Stoneville, MS 38776, USA
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Reisig DD, DiFonzo C, Dively G, Farhan Y, Gore J, Smith J. Best Management Practices to Delay the Evolution of Bt Resistance in Lepidopteran Pests Without High Susceptibility to Bt Toxins in North America. JOURNAL OF ECONOMIC ENTOMOLOGY 2022; 115:10-25. [PMID: 34922393 DOI: 10.1093/jee/toab247] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Indexed: 06/14/2023]
Abstract
Canadian and United States (US) insect resistance management (IRM) programs for lepidopteran pests in Bacillus thuriengiensis (Bt)-expressing crops are optimally designed for Ostrinia nubilalis Hübner in corn (Zea mays L.) and Chloridea virescens Fabricius in cotton (Gossypium hirsutum L.). Both Bt corn and cotton express a high dose for these pests; however, there are many other target pests for which Bt crops do not express high doses (commonly referred to as nonhigh dose pests). Two important lepidopteran nonhigh dose (low susceptibility) pests are Helicoverpa zea Boddie (Lepidoptera: Noctuidae) and Striacosta albicosta Smith (Lepidoptera: Noctuidae). We highlight both pests as cautionary examples of exposure to nonhigh dose levels of Bt toxins when the IRM plan was not followed. Moreover, IRM practices to delay Bt resistance that are designed for these two ecologically challenging and important pests should apply to species that are more susceptible to Bt toxins. The purpose of this article is to propose five best management practices to delay the evolution of Bt resistance in lepidopteran pests with low susceptibility to Bt toxins in Canada and the US: 1) better understand resistance potential before commercialization, 2) strengthen IRM based on regional pest pressure by restricting Bt usage where it is of little benefit, 3) require and incentivize planting of structured corn refuge everywhere for single toxin cultivars and in the southern US for pyramids, 4) integrate field and laboratory resistance monitoring programs, and 5) effectively use unexpected injury thresholds.
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Affiliation(s)
- Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, 207 Research Station Road, Plymouth, NC, 27962, USA
| | - Chris DiFonzo
- Department of Entomology, Michigan State University, 288 Farm Lane, East Lansing, MI, 48824, USA
| | - Galen Dively
- Department of Entomology, University of Maryland, College Park, MD, 20742, USA
| | - Yasmine Farhan
- Department of Plant Agriculture, University of Guelph Ridgetown Campus, 120 Main Street East, Ridgetown, ON, N0P 2C0, Canada
| | - Jeff Gore
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, P.O. Box 197, Stoneville, MS, 38776, USA
| | - Jocelyn Smith
- Department of Plant Agriculture, University of Guelph Ridgetown Campus, 120 Main Street East, Ridgetown, ON, N0P 2C0, Canada
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Walsh TK, Heckel DG, Wu Y, Downes S, Gordon KHJ, Oakeshott JG. Determinants of Insecticide Resistance Evolution: Comparative Analysis Among Heliothines. ANNUAL REVIEW OF ENTOMOLOGY 2022; 67:387-406. [PMID: 34995087 DOI: 10.1146/annurev-ento-080421-071655] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It is increasingly clear that pest species vary widely in their propensities to develop insecticide resistance. This review uses a comparative approach to analyze the key pest management practices and ecological and biochemical or genetic characteristics of the target that contribute to this variation. We focus on six heliothine species, three of which, Helicoverpa armigera, Heliothis virescens, and Helicoverpa zea, have developed resistances to many pesticide classes. The three others, Helicoverpa punctigera, Helicoverpa assulta, and Helicoverpa gelotopoeon, also significant pests, have developed resistance to very few pesticide classes. We find that host range and movement between alternate hosts are key ecological traits that influence effective selection intensities for resistance. Operational issues are also critical; area-wide, cross-pesticide management practices that account for these ecological factors are key to reducing selection intensity. Without such management, treatment using broad-spectrum chemicals serves to multiply the effects of host plant preference, preadaptive detoxification ability, and high genetic diversity to create a pesticide treadmill for the three high-propensity species.Without rigorous ongoing management, such a treadmill could still develop for newer, more selective chemistries and insecticidal transgenic crops.
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Affiliation(s)
- T K Walsh
- CSIRO Black Mountain Laboratories, Canberra, Australian Capital Territory, Australia;
- Applied BioSciences, Macquarie University, Sydney, New South Wales, Australia
| | - D G Heckel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Yidong Wu
- Key Laboratory of Plant Immunity and College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - S Downes
- CSIRO McMaster Laboratories, Armidale, New South Wales, Australia
| | - K H J Gordon
- CSIRO Black Mountain Laboratories, Canberra, Australian Capital Territory, Australia;
| | - J G Oakeshott
- CSIRO Black Mountain Laboratories, Canberra, Australian Capital Territory, Australia;
- Applied BioSciences, Macquarie University, Sydney, New South Wales, Australia
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Kerns DD, Yang F, Kerns DL, Stewart SD. Evaluation of Bt resistance in Helicoverpa zea (Lepidoptera: Noctuidae) strains using various Bt cotton plant tissues. PEST MANAGEMENT SCIENCE 2022; 78:95-103. [PMID: 34448529 DOI: 10.1002/ps.6611] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Diet-overlay bioassays suggest that Helicoverpa zea (Lepidoptera: Noctuidae) field populations have developed resistance to some of the Bt insecticidal proteins that are constituents of the pyramids expressed in the second and third generation Bt cotton technologies. Unfortunately, these bioassays are not always a reliable indicator for how a seemingly resistant population will perform in an actual cotton field, and thus, leaf tissue bioassays have been suggested as a method to better assess field performance. However, bollworm larvae typically prefer to feed on floral tissue rather than leaf tissue, and an alternative cotton structure type may be more ideal for use in plant tissue-based bioassays. A series of diet-overlay bioassays using Bt proteins and Bt cotton plant tissue were conducted with laboratory susceptible (Bz-SS) and resistant (Cry-RR, resistant to Cry1Ac and Cry2Ab) H. zea strains to determine if plant tissue overlays could detect resistance and which cotton plant structure type would be most ideal for use in bioassays. RESULTS Results suggest that diet overlays using lyophilized plant tissue were able to detect resistance. Lyophilized tissue from white flowers was most ideal for use in bioassays, whereas tissue from non-Bt bolls and leaves affected larval health and behavior, confounding assay results. CONCLUSION Overlays using white flower tissue could potentially be used to supplement Bt protein overlays and provide an improved assessment of larval performance on Bt cotton technologies. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Dawson D Kerns
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, USA
| | - Fei Yang
- Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - Scott D Stewart
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, USA
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Lawrie RD, Mitchell RD, Deguenon JM, Ponnusamy L, Reisig D, Pozo-Valdivia AD, Kurtz RW, Roe RM. Characterization of Long Non-Coding RNAs in the Bollworm, Helicoverpa zea, and Their Possible Role in Cry1Ac-Resistance. INSECTS 2021; 13:12. [PMID: 35055855 PMCID: PMC8779162 DOI: 10.3390/insects13010012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 12/19/2021] [Accepted: 12/20/2021] [Indexed: 12/13/2022]
Abstract
Multiple insect pest species have developed field resistance to Bt-transgenic crops. There has been a significant amount of research on protein-coding genes that contribute to resistance, such as the up-regulation of protease activity or altered receptors. However, our understanding of the role of non-protein-coding mechanisms in Bt-resistance is minimal, as is also the case for resistance to chemical pesticides. To address this problem relative to Bt, RNA-seq was used to examine statistically significant, differential gene expression between a Cry1Ac-resistant (~100-fold resistant) and Cry1Ac-susceptible strain of Helicoverpa zea, a prevalent caterpillar pest in the USA. Significant differential expression of putative long non-coding RNAs (lncRNAs) was found in the Cry1Ac-resistant strain (58 up- and 24 down-regulated gene transcripts with an additional 10 found only in resistant and four only in susceptible caterpillars). These lncRNAs were examined as potential pseudogenes and for their genomic proximity to coding genes, both of which can be indicative of regulatory relationships between a lncRNA and coding gene expression. A possible pseudogenic lncRNA was found with similarities to a cadherin. In addition, putative lncRNAs were found significantly proximal to a serine protease, ABC transporter, and CYP coding genes, potentially involved in the mechanism of Bt and/or chemical insecticide resistance. Characterization of non-coding genetic mechanisms in Helicoverpa zea will improve the understanding of the genomic evolution of insect resistance, improve the identification of specific regulators of coding genes in general (some of which could be important in resistance), and is the first step for potentially targeting these regulators for pest control and resistance management (using molecular approaches, such as RNAi and others).
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Affiliation(s)
- Roger D. Lawrie
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7647, 3230 Ligon Street, Raleigh, NC 27695, USA; (R.D.L.); (R.D.M.III); (J.M.D.); (L.P.)
- Environmental and Molecular Toxicology Program, Department of Biology, College of Sciences, North Carolina State University, 2601 Stinson Drive, Raleigh, NC 27606, USA
| | - Robert D. Mitchell
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7647, 3230 Ligon Street, Raleigh, NC 27695, USA; (R.D.L.); (R.D.M.III); (J.M.D.); (L.P.)
- Office of Pesticide Programs, Invertebrate and Vertebrate Branch 1, Registration Division, U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, Washington, DC 20460, USA
| | - Jean Marcel Deguenon
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7647, 3230 Ligon Street, Raleigh, NC 27695, USA; (R.D.L.); (R.D.M.III); (J.M.D.); (L.P.)
| | - Loganathan Ponnusamy
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7647, 3230 Ligon Street, Raleigh, NC 27695, USA; (R.D.L.); (R.D.M.III); (J.M.D.); (L.P.)
| | - Dominic Reisig
- Vernon G. James Research & Extension Center, Department of Entomology and Plant Pathology, 207 Research Station Road, Plymouth, NC 27962, USA; (D.R.); (A.D.P.-V.)
| | - Alejandro Del Pozo-Valdivia
- Vernon G. James Research & Extension Center, Department of Entomology and Plant Pathology, 207 Research Station Road, Plymouth, NC 27962, USA; (D.R.); (A.D.P.-V.)
| | - Ryan W. Kurtz
- Cotton Incorporated, 6399 Weston Parkway, Cary, NC 27513, USA;
| | - Richard Michael Roe
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7647, 3230 Ligon Street, Raleigh, NC 27695, USA; (R.D.L.); (R.D.M.III); (J.M.D.); (L.P.)
- Environmental and Molecular Toxicology Program, Department of Biology, College of Sciences, North Carolina State University, 2601 Stinson Drive, Raleigh, NC 27606, USA
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Genome evolution in an agricultural pest following adoption of transgenic crops. Proc Natl Acad Sci U S A 2021; 118:2020853118. [PMID: 34930832 PMCID: PMC8719884 DOI: 10.1073/pnas.2020853118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2021] [Indexed: 12/14/2022] Open
Abstract
Evolution of resistance to management approaches in agricultural landscapes is common and results in economic losses. Early detection of pest resistance prior to significant crop damage would benefit the agricultural community. It has been hypothesized that new genomic approaches could track molecular signals of emerging resistance and trigger efforts to preempt widespread damage. We tested this hypothesis by quantifying genomic changes in the pest Helicoverpa zea over a 15-y period concurrent with commercialization of transgenic Bacillus thuringiensis–expressing crops and their subsequent loss of efficacy. Our results demonstrate the complex nature of evolution in agricultural ecosystems and provide insight into the potential and pitfalls of using genomic approaches for resistance monitoring. Replacing synthetic insecticides with transgenic crops for pest management has been economically and environmentally beneficial, but these benefits erode as pests evolve resistance. It has been proposed that novel genomic approaches could track molecular signals of emerging resistance to aid in resistance management. To test this, we quantified patterns of genomic change in Helicoverpa zea, a major lepidopteran pest and target of transgenic Bacillus thuringiensis (Bt) crops, between 2002 and 2017 as both Bt crop adoption and resistance increased in North America. Genomic scans of wild H. zea were paired with quantitative trait locus (QTL) analyses and showed the genomic architecture of field-evolved Cry1Ab resistance was polygenic, likely arising from standing genetic variation. Resistance to pyramided Cry1A.105 and Cry2Ab2 toxins was controlled by fewer loci. Of the 11 previously described Bt resistance genes, 9 showed no significant change over time or major effects on resistance. We were unable to rule out a contribution of aminopeptidases (apns), as a cluster of apn genes were found within a Cry-associated QTL. Molecular signals of emerging Bt resistance were detectable as early as 2012 in our samples, and we discuss the potential and pitfalls of whole-genome analysis for resistance monitoring based on our findings. This first study of Bt resistance evolution using whole-genome analysis of field-collected specimens demonstrates the need for a more holistic approach to examining rapid adaptation to novel selection pressures in agricultural ecosystems.
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Calvin W, Yang F, Brown SA, Catchot AL, Crow WD, Cook DR, Gore J, Kurtz R, Lorenz GM, Seiter NJ, Stewart SD, Towles T, Kerns DL. Development of Economic Thresholds Toward Bollworm (Lepidoptera: Noctuidae), Management in Bt Cotton, and Assessment of the Benefits From Treating Bt Cotton With Insecticide. JOURNAL OF ECONOMIC ENTOMOLOGY 2021; 114:2493-2504. [PMID: 34625803 DOI: 10.1093/jee/toab173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Indexed: 06/13/2023]
Abstract
Widespread field-evolved resistance of bollworm [Helicoverpa zea (Boddie)] to Cry1 and Cry2 Bt proteins has threatened the utility of Bt cotton for managing bollworm. Consequently, foliar insecticide applications have been widely adopted to provide necessary additional control. Field experiments were conducted across the Mid-South and in Texas to devise economic thresholds for foliar insecticide applications targeting bollworm in cotton. Bt cotton technologies including TwinLink (TL; Cry1Ab+Cry2Ae), TwinLink Plus (TLP; Cry1Ab+Cry2Ae+Vip3Aa), Bollgard II (BG2; Cry1Ac+Cry2Ab), Bollgard 3 (BG3; Cry1Ac+Cry2Ab+Vip3Aa), WideStrike (WS; Cry1Ac+Cry1F), WideStrike 3 (WS3; Cry1Ac+Cry1F+Vip3Aa), and a non-Bt (NBT) variety were evaluated. Gain threshold, economic injury level, and economic thresholds were determined. A 6% fruiting form injury threshold was selected and compared with preventive treatments utilizing chlorantraniliprole. Additionally, the differences in yield from spraying bollworms was compared among Bt cotton technologies. The 6% fruiting form injury threshold resulted in a 25 and 75% reduction in insecticide applications relative to preventive sprays for WS and BG2, respectively. All Bt technologies tested in the current study exhibited a positive increase in yield from insecticide application. The frequency of yield increase from spraying WS was comparable to that of NBT. Significant yield increases due to insecticide application occurred less frequently in triple-gene Bt cotton. However, their frequencies were close to the dual-gene Bt cotton, except for WS. The results of our study suggest that 6% fruiting form injury is a viable threshold, and incorporating a vetted economic threshold into an Integrated Pest Management program targeting bollworm should improve the sustainability of cotton production.
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Affiliation(s)
- Wilfrid Calvin
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
| | - Fei Yang
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
| | - Sebe A Brown
- Dean Lee Research Station, Louisisana State University, 8105 Tom Bowman Drive, Alexandria, LA 71302, USA
| | - Angus L Catchot
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, P.O. Box 9775, Mississippi State, MS 39762, USA
| | - Whitney D Crow
- Delta REC, Mississippi State University, P.O. Box 197, Stoneville, MS 38776, USA
| | - Donald R Cook
- Delta REC, Mississippi State University, P.O. Box 197, Stoneville, MS 38776, USA
| | - Jeffrey Gore
- Delta REC, Mississippi State University, P.O. Box 197, Stoneville, MS 38776, USA
| | - Ryan Kurtz
- Cotton Incorporated, 6399 Weston Pkwy, Cary, NC 27513, USA
| | - Gustav M Lorenz
- Department of Entomology and Plant Pathology, University of Arkansas, 2001 Highway 70 E., Lonoke, AR 72086, USA
| | - Nicholas J Seiter
- Crop Sciences, 380 National Soybean Research Center, University of Illinois, 1101 W. Peabody Drive, Urbana, IL 61801, USA
| | - Scott D Stewart
- West Tennessee REC, University of Tennessee, 605 Airways Boulevard, Jackson, TN 38301, USA
| | - Tyler Towles
- Macon Ridge Research Station, Louisisana State University, 212A Macon Ridge Road, Winnsboro, LA 71295, USA
| | - David L Kerns
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
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Dorman SJ, Hopperstad KA, Reich BJ, Majumder S, Kennedy G, Reisig DD, Greene JK, Reay-Jones FP, Collins G, Bacheler JS, Huseth AS. Landscape-level variation in Bt crops predict Helicoverpa zea (Lepidoptera: Noctuidae) resistance in cotton agroecosystems. PEST MANAGEMENT SCIENCE 2021; 77:5454-5462. [PMID: 34333843 DOI: 10.1002/ps.6585] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 07/25/2021] [Accepted: 08/01/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Helicoverpa zea (Boddie) damage to Bt cotton and maize has increased as a result of widespread Bt resistance across the USA Cotton Belt. Our objective was to link Bt crop production patterns to cotton damage through a series of spatial and temporal surveys of commercial fields to understand how Bt crop production relates to greater than expected H. zea damage to Bt cotton. To do this, we assembled longitudinal cotton damage data that spanned the Bt adoption period, collected cotton damage data since Bt resistance has been detected, and estimated local population susceptibility using replicated on-farm studies that included all Bt pyramids marketed in cotton. RESULTS Significant year effects of H. zea damage frequency in commercial cotton were observed throughout the Bt adoption period, with a recent damage increase after 2012. Landscape-level Bt crop production intensity over time was positively associated with the risk of H. zea damage in two- and three-toxin pyramided Bt cotton. Helicoverpa zea damage also varied across Bt toxin types in spatially replicated on-farm studies. CONCLUSIONS Landscape-level predictors of H. zea damage in Bt cotton can be used to identify heightened Bt resistance risk areas and serves as a model to understand factors that drive pest resistance evolution to Bt toxins in the southeastern United States. These results provide a framework for more effective insect resistance management strategies to be used in combination with conventional pest management practices that improve Bt trait durability while minimizing the environmental footprint of row crop agriculture. © 2021 Society of Chemical Industry. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
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Affiliation(s)
- Seth J Dorman
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
- USDA-ARS Forage Seed and Cereal Research Unit, Corvallis, OR, USA
| | - Kristen A Hopperstad
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Brian J Reich
- Department of Statistics, North Carolina State University, Raleigh, NC, USA
| | - Suman Majumder
- Department of Statistics, North Carolina State University, Raleigh, NC, USA
| | - George Kennedy
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon James Research and Extension Center, Plymouth, NC, USA
| | - Jeremy K Greene
- Department of Plant and Environmental Sciences, Clemson University, Edisto Research and Education Center, Blackville, SC, USA
| | - Francis Pf Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, Florence, SC, USA
| | - Guy Collins
- Department of Crop and Soil Science, North Carolina State University, Raleigh, NC, USA
| | - Jack S Bacheler
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Anders S Huseth
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
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Dorman SJ, Kudenov MW, Lytle AJ, Griffith EH, Huseth AS. Computer vision for detecting field-evolved lepidopteran resistance to Bt maize. PEST MANAGEMENT SCIENCE 2021; 77:5236-5245. [PMID: 34310008 DOI: 10.1002/ps.6566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 07/15/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Resistance evolution of lepidopteran pests to Bacillus thuringiensis (Bt) toxins produced in maize and cotton is a significant issue worldwide. Effective toxin stewardship requires reliable detection of field-evolved resistance to enable the implementation of mitigation strategies. Currently, visual estimates of maize injury are used to document changing susceptibility. In this study, we evaluated an existing maize injury monitoring protocol used to estimate Bt resistance levels in Helicoverpa zea (Lepidoptera: Noctuidae). RESULTS We detected high interobserver variability across multiple injury metrics, suggesting that the precision and accuracy of maize injury detection could be improved. To do this, we developed a computer vision-based algorithm to measure H. zea injury. Algorithm estimates were more accurate and precise than a sample of human observers. Moreover, observer estimates tended to overpredict H. zea injury, which may increase the false-positive rate, leading to prophylactic insecticide application and unnecessary regulatory action. CONCLUSIONS Automated detection and tracking of lepidopteran resistance evolution to Bt toxins are critical for genetically engineered crop stewardship to prevent the use of additional insecticides to combat resistant pests. Advantages of this computerized screening are: (i) standardized Bt injury metrics in space and time, (ii) preservation of digital data for cross-referencing when thresholds are reached, and (iii) the ability to increase sample sizes significantly. This technological solution represents a significant step toward improving confidence in resistance monitoring efforts among researchers, regulators and the agricultural biotechnology industry.
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Affiliation(s)
- Seth J Dorman
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Michael W Kudenov
- Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC, USA
| | - Amanda J Lytle
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Emily H Griffith
- Department of Statistics, North Carolina State University, Raleigh, NC, USA
| | - Anders S Huseth
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
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Yang F, Kerns DL, Little NS, Santiago González JC, Tabashnik BE. Early Warning of Resistance to Bt Toxin Vip3Aa in Helicoverpa zea. Toxins (Basel) 2021; 13:618. [PMID: 34564622 PMCID: PMC8473270 DOI: 10.3390/toxins13090618] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/24/2021] [Accepted: 08/27/2021] [Indexed: 11/17/2022] Open
Abstract
Evolution of resistance by pests can reduce the benefits of crops genetically engineered to produce insecticidal proteins from Bacillus thuringiensis (Bt). Because of the widespread resistance of Helicoverpa zea to crystalline (Cry) Bt toxins in the United States, the vegetative insecticidal protein Vip3Aa is the only Bt toxin produced by Bt corn and cotton that remains effective against some populations of this polyphagous lepidopteran pest. Here we evaluated H. zea resistance to Vip3Aa using diet bioassays to test 42,218 larvae from three lab strains and 71 strains derived from the field during 2016 to 2020 in Arkansas, Louisiana, Mississippi, Tennessee, and Texas. Relative to the least susceptible of the three lab strains tested (BZ), susceptibility to Vip3Aa of the field-derived strains decreased significantly from 2016 to 2020. Relative to another lab strain (TM), 7 of 16 strains derived from the field in 2019 were significantly resistant to Vip3Aa, with up to 13-fold resistance. Susceptibility to Vip3Aa was significantly lower for strains derived from Vip3Aa plants than non-Vip3Aa plants, providing direct evidence of resistance evolving in response to selection by Vip3Aa plants in the field. Together with previously reported data, the results here convey an early warning of field-evolved resistance to Vip3Aa in H. zea that supports calls for urgent action to preserve the efficacy of this toxin.
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Affiliation(s)
- Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA; (D.L.K.); (J.C.S.G.)
| | - David L. Kerns
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA; (D.L.K.); (J.C.S.G.)
| | | | - José C. Santiago González
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA; (D.L.K.); (J.C.S.G.)
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Effectiveness of the natural resistance management refuge for Bt-cotton is dominated by local abundance of soybean and maize. Sci Rep 2021; 11:17601. [PMID: 34475501 PMCID: PMC8413434 DOI: 10.1038/s41598-021-97123-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/18/2021] [Indexed: 11/18/2022] Open
Abstract
Genetically engineered crops expressing Bacillus thuringiensis (Bt) Cry toxins have transformed insect management in maize and cotton, reducing insecticide use and associated off-target effects. To mitigate the risk that pests evolve resistance to Bt crops, the US Environmental Protection Agency requires resistance management measures. The approved resistance management plan for Bt maize in cotton production regions requires a structured refuge of non-Bt maize equal to 20% of the maize planted; that for Bt cotton relies on the presence of an unstructured natural refuge comprising both non-Bt crop and non-crop hosts. We examined how abundance of Bt crops (cotton and maize) and an important non-Bt crop (soybean) component of the natural refuge affect resistance to Bt Cry1Ac toxin in local populations of Helicoverpa zea, an important lepidopteran pest impacted by Bt cotton and maize. We show refuge effectiveness is responsive to local abundances of maize and cotton and non-Bt soybean, and maize, in its role as a source of H. zea infesting cotton and non-Bt hosts, influences refuge effectiveness. These findings have important implications for commercial and regulatory decisions regarding deployment of Bt toxins targeting H. zea in maize, cotton, and other crops and for assumptions regarding efficacy of natural refuges.
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Dimase M, Brown S, Head GP, Price PA, Walker W, Yu W, Huang F. Performance of Bt-susceptible and -heterozygous dual-gene resistant genotypes of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in seed blends of non-Bt and pyramided Bt maize. INSECT SCIENCE 2021; 28:1147-1158. [PMID: 32662592 DOI: 10.1111/1744-7917.12850] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 05/28/2023]
Abstract
A seed blend refuge has been implemented in the U.S. Corn Belt for Bt maize resistance management. The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a target pest of Bt maize in the Americas. The larvae of this pest are mobile, which may affect the efficacy of seed blend refuges. In this study, field and greenhouse trials were conducted to determine the performance of Bt-susceptible (aabb) and -heterozygous dual-gene-resistant (AaBb) genotypes of S. frugiperda in seed blends of non-Bt and pyramided Bt maize. Three field trials evaluated larval survival, larval growth, and plant injury with aabb in seed blends of Bt maize expressing Cry1A.105/Cry2Ab2/Vip3A with 0-30% non-Bt seeds. Greenhouse tests investigated the performance of aabb and AaBb in seed blends of Cry1A.105/Cry2Ab2 with 0-30% non-Bt seeds. In pure non-Bt maize plots, after 9-13 d of neonates being released on the plants, 0.39 and 0.65 larvae/plant survived with leaf injury ratings of 4.7 and 5.9 (Davis's 1-9 scale) in the field and greenhouse, respectively. In contrast, live larvae and plant injury were virtually not observed on Bt plants across all planting patterns. Larval occurrence and plant injury by aabb on non-Bt plants were similar between seed blends and pure non-Bt plantings, suggesting that the blended refuges could provide an equivalent susceptible population as structured refuge under the test conditions. In the greenhouse, the two insect genotypes in seed blends performed similarly, indicating that the seed blends did not provide more favorable conditions for AaBb over aabb. The information generated from this study should be useful in managing S. frugiperda and evaluating if send blends could be suitable refuge options for Bt resistance management in the regions where the insect is a primary target pest.
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Affiliation(s)
- Marcelo Dimase
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
| | - Sebe Brown
- Dean Lee Research Station, Louisiana State University Agricultural Center, Alexandria, Louisiana, USA
| | | | | | - Wade Walker
- Macon Ridge Research Station, Louisiana State University Agricultural Center, Winnsboro, Louisiana, USA
| | - Wenbo Yu
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
| | - Fangneng Huang
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
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Huang F. Resistance of the fall armyworm, Spodoptera frugiperda, to transgenic Bacillus thuringiensis Cry1F corn in the Americas: lessons and implications for Bt corn IRM in China. INSECT SCIENCE 2021; 28:574-589. [PMID: 32478944 DOI: 10.1111/1744-7917.12826] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 04/24/2020] [Accepted: 05/21/2020] [Indexed: 06/11/2023]
Abstract
The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a major target pest of Bt crops (e.g., corn, cotton, and soybean) in North and South America. This pest has recently invaded Africa and Asia including China and the invasion has placed a great threat to the food security in many countries of these two continents. Due to the extensive use of Bt crops, practical resistance of S. frugiperda to Cry1F corn (TC 1507) with field control problems has widely occurred in Puerto Rico, Brazil, Argentina, and the mainland United States. Analyzing data generated from decade-long studies showed that several factors might have contributed to the wide development of the resistance. These factors include (1) limited modes of action of Bt proteins used in Bt crops; (2) cross-resistance among Cry1 proteins; (3) use of nonhigh dose Bt crop traits; (4) that the resistance is complete on Bt corn plants; (5) abundant in initial Cry1F resistance alleles; and (6) lack of fitness costs/recessive fitness costs of the resistance. The long-term use of Bt crop technology in the Americas suggests that Bt corn can be an effective tool for controlling S. frugiperda in China. IRM programs for Bt corn in China should be as simple as possible to be easily adopted by small-scale growers. The following aspects may be considered in its Bt corn IRM programs: (1) use of only "high dose" traits for both S. frugiperda and stalk borers; (2) developing and implementing a combined resistance monitoring program; (3) use "gene pyramiding" as a primary IRM strategy; and (4) if possible, Bt corn may not be planted in the areas where S. frugiperda overwinters. Lessons and experience gained from the global long-term use of Bt crops should have values in improving IRM programs in the Americas, as well as for a sustainable use of Bt corn technology in China.
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Affiliation(s)
- Fangneng Huang
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
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Babu A, Reisig DD, Pes MP, Ranger CM, Chamkasem N, Reding ME. Effects of chlorantraniliprole residual on Helicoverpa zea in Bt and non-Bt cotton. PEST MANAGEMENT SCIENCE 2021; 77:2367-2374. [PMID: 33415822 DOI: 10.1002/ps.6263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 12/30/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Helicoverpa zea is managed with foliar applications of chlorantraniliprole in cotton varieties that do not express the Vip3Aa19 toxin in the US Cotton Belt. Foliar insecticides and Bt could interact to influence larval susceptibility. Therefore, it has been suggested that chlorantraniliprole can be used as a tool for Bt resistance management. We designed field and laboratory studies to test the hypothesis that the interaction of Bt toxin and chlorantraniliprole application would result in lower H. zea larval survival when compared to the individual effect of Bt or chlorantraniliprole alone. We also tested for these interactions over time, since chlorantraniliprole residual has not been studied in cotton. RESULTS Results from two field experiments and two laboratory experiments were similar. We found no interactions with Bt and chlorantraniliprole using data not corrected for natural mortality in untreated plots, indicating that these factors did not interact to influence survival. Moreover, we found that Bt and chlorantraniliprole did not interact to influence larval weight and instar. Chlorantraniliprole had lethal and sublethal effects on H. zea larval growth parameters feeding on cotton leaves up to 22 days after application, the final time period that we tested. Finally, concentration of chlorantraniliprole in the leaf was associated with larval survival for the duration of this study, but not larval growth or instar. CONCLUSION Our findings complement the recommendation to use chlorantraniliprole for managing H. zea in cotton, given its long-residual effects. However, the utility of chlorantraniliprole as a Bt-resistance management tool for H. zea remains unclear. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Arun Babu
- Department of Entomology and Plant Pathology, Vernon G. James Research and Extension Center, North Carolina State University, Plymouth, NC, USA
- Department of Entomology, College of Agricultural and Environmental Sciences, University of Georgia, 413 Biological Sciences, Athens, GA, 30602, USA
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, Vernon G. James Research and Extension Center, North Carolina State University, Plymouth, NC, USA
| | | | - Christopher M Ranger
- Application Technology Research Unit, USDA-Agricultural Research Service, Wooster, OH, USA
| | - Narong Chamkasem
- Southeast Regional Laboratory, U.S. Food and Drug Administration, Atlanta, GA, USA
| | - Michael E Reding
- Application Technology Research Unit, USDA-Agricultural Research Service, Wooster, OH, USA
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Deguenon JM, Dhammi A, Ponnusamy L, Travanty NV, Cave G, Lawrie R, Mott D, Reisig D, Kurtz R, Roe RM. Bacterial Microbiota of Field-Collected Helicoverpa zea (Lepidoptera: Noctuidae) from Transgenic Bt and Non-Bt Cotton. Microorganisms 2021; 9:microorganisms9040878. [PMID: 33923893 PMCID: PMC8072973 DOI: 10.3390/microorganisms9040878] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/07/2021] [Accepted: 04/16/2021] [Indexed: 12/15/2022] Open
Abstract
The bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), is an important agricultural pest in U.S. cotton and is managed using transgenic hybrids that produce insecticidal proteins from the bacterium, Bacillus thuringiensis (Bt). The reduced efficacy against H. zea caterpillars of Bt plants expressing Cry toxins is increasing in the field. In a first step towards understanding Bt cotton–bollworm–microbiota interactions, we investigated the internal bacterial microbiota of second–third stadium H. zea collected in the field from non-Bt versus Bt (WideStrike) cotton in close proximity (in North Carolina, USA). The bacterial populations were analyzed using culture-dependent and -independent molecular approaches. We found that WideStrike samples had a higher bacterial density and diversity per larva than insects collected from non-Bt cotton over two field seasons: 8.42 ± 0.23 and 5.36 ± 0.75 (log10 colony forming units per insect) for WideStrike compared to 6.82 ± 0.20 and 4.30 ± 0.56 for non-Bt cotton for seasons 1 and 2, respectively. Fifteen phyla, 103 families, and 229 genera were identified after performing Illumina sequencing of the 16S rRNA. At the family level, Enterobacteriaceae and Enterococcaceae were the most abundant taxa. The Enterococcaceae family was comprised mostly of Enterococcus species (E. casseliflavus and another Enterococcus sp.). Members of the Enterococcus genus can acidify their environment and can potentially reduce the alkaline activation of some Bt toxins. These findings argue for more research to better understand the role of cotton–bollworm–bacteria interactions and the impact on Bt toxin caterpillar susceptibility.
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Affiliation(s)
- Jean M. Deguenon
- Department of Entomology and Plant Pathology, North Carolina State University, 3230 Ligon Street, Campus Box 7647, Raleigh, NC 27695-7647, USA; (J.M.D.); (A.D.); (N.V.T.); (G.C.); (R.L.); (D.M.); (D.R.); (R.M.R.)
| | - Anirudh Dhammi
- Department of Entomology and Plant Pathology, North Carolina State University, 3230 Ligon Street, Campus Box 7647, Raleigh, NC 27695-7647, USA; (J.M.D.); (A.D.); (N.V.T.); (G.C.); (R.L.); (D.M.); (D.R.); (R.M.R.)
| | - Loganathan Ponnusamy
- Department of Entomology and Plant Pathology, North Carolina State University, 3230 Ligon Street, Campus Box 7647, Raleigh, NC 27695-7647, USA; (J.M.D.); (A.D.); (N.V.T.); (G.C.); (R.L.); (D.M.); (D.R.); (R.M.R.)
- Correspondence:
| | - Nicholas V. Travanty
- Department of Entomology and Plant Pathology, North Carolina State University, 3230 Ligon Street, Campus Box 7647, Raleigh, NC 27695-7647, USA; (J.M.D.); (A.D.); (N.V.T.); (G.C.); (R.L.); (D.M.); (D.R.); (R.M.R.)
| | - Grayson Cave
- Department of Entomology and Plant Pathology, North Carolina State University, 3230 Ligon Street, Campus Box 7647, Raleigh, NC 27695-7647, USA; (J.M.D.); (A.D.); (N.V.T.); (G.C.); (R.L.); (D.M.); (D.R.); (R.M.R.)
| | - Roger Lawrie
- Department of Entomology and Plant Pathology, North Carolina State University, 3230 Ligon Street, Campus Box 7647, Raleigh, NC 27695-7647, USA; (J.M.D.); (A.D.); (N.V.T.); (G.C.); (R.L.); (D.M.); (D.R.); (R.M.R.)
| | - Dan Mott
- Department of Entomology and Plant Pathology, North Carolina State University, 3230 Ligon Street, Campus Box 7647, Raleigh, NC 27695-7647, USA; (J.M.D.); (A.D.); (N.V.T.); (G.C.); (R.L.); (D.M.); (D.R.); (R.M.R.)
| | - Dominic Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, 3230 Ligon Street, Campus Box 7647, Raleigh, NC 27695-7647, USA; (J.M.D.); (A.D.); (N.V.T.); (G.C.); (R.L.); (D.M.); (D.R.); (R.M.R.)
| | - Ryan Kurtz
- Cotton Incorporated, Cary, NC 27513, USA;
| | - R. Michael Roe
- Department of Entomology and Plant Pathology, North Carolina State University, 3230 Ligon Street, Campus Box 7647, Raleigh, NC 27695-7647, USA; (J.M.D.); (A.D.); (N.V.T.); (G.C.); (R.L.); (D.M.); (D.R.); (R.M.R.)
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Del Pozo-Valdivia AI, Reisig DD, Braswell L, Greene JK, Roberts P, Taylor SV. Economic Injury Levels for Bt-resistant Helicoverpa zea (Lepidoptera: Noctuidae) in Cotton. JOURNAL OF ECONOMIC ENTOMOLOGY 2021; 114:747-756. [PMID: 33615386 DOI: 10.1093/jee/toab012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Indexed: 06/12/2023]
Abstract
Thresholds for Helicoverpa zea (Boddie) in cotton Gossypium hirsutum L. have been understudied since the widespread adoption of Bt cotton in the United States. Our study was possible due to the widespread presence of H. zea populations with Cry-toxin resistance. We initiated progressive spray timing experiments using three Bt cotton brands (Deltapine, Stoneville, and Phytogen) widely planted across the U.S. Cotton Belt expressing pyramided toxins in the Cry1A, Cry2, and Vip3Aa19 families. We timed foliar insecticide treatments based on week of bloom to manipulate H. zea populations in tandem with crop development during 2017 and 2018. We hypothesized that non-Bt cotton, cotton expressing Cry toxins alone, and cotton expressing Cry and Vip3Aa19 toxins would respond differently to H. zea feeding. We calculated economic injury levels to support the development of economic thresholds from significant responses. Pressure from H. zea was high during both years. Squares and bolls damaged by H. zea had the strongest negative yield associations, followed by larval number on squares. There were fewer yield associations with larval number on bolls and with number of H. zea eggs on the plant. Larval population levels were very low on varieties expressing Vip3Aa19. Yield response varied across experiments and varieties, suggesting that it is difficult to pinpoint precise economic injury levels. Nonetheless, our results generally suggest that current economic thresholds for H. zea in cotton are too high. Economic injury levels from comparisons between non-Bt varieties and those expressing only Cry toxins could inform future thresholds once H. zea evolves resistance to Vip3Aa19.
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Affiliation(s)
- Alejandro I Del Pozo-Valdivia
- Department of Entomology, Hampton Roads Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Virginia Beach, VA, USA
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC, USA
| | - Lewis Braswell
- Product Biology Division, Syngenta Crop Protection Inc., Greensboro, NC, USA
| | - Jeremy K Greene
- Department of Plant and Environmental Sciences, Edisto Research and Education Center, Clemson University, Blackville, SC, USA
| | - Phillip Roberts
- Department of Entomology, University of Georgia, Tifton Campus, Tifton, GA, USA
| | - Sally V Taylor
- Department of Entomology, Tidewater Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Suffolk, VA, USA
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Yang F, Santiago González JC, Sword GA, Kerns DL. Genetic basis of resistance to the Vip3Aa Bt protein in Helicoverpa zea. PEST MANAGEMENT SCIENCE 2021; 77:1530-1535. [PMID: 33201547 DOI: 10.1002/ps.6176] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/30/2020] [Accepted: 11/17/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Helicoverpa zea is a destructive pest and target of maize and cotton expressing Cry and Vip3Aa proteins in North America. The efficacy of Cry proteins against H. zea in the USA has been largely compromised by resistance. A rapid shift towards planting Bt cotton and maize producing Vip3Aa will accelerate evolution of resistance to Vip3Aa in H. zea. Research on the genetic basis of Vip3Aa resistance in H. zea is urgently needed, and can provide fundamental information for managing resistance in this pest. Here, we characterize the inheritance of Vip3Aa resistance in H. zea. RESULTS Susceptibility of a Vip3Aa-susceptible strain (SS), a resistant strain (RR), and progeny from different crosses against Vip3Aa39 was determined. RR was established from an F2 screening of a population from Texas sampled in 2019. RR had a resistance ratio of 45194.1-fold against Vip3Aa39 relative to SS. Maternal effects and sex linkage were absent in RR. The dominance D value, calculated based on median lethal concentration (LC50 ) values, was -1.0 and the effective dominance (DML ), calculated based on a given Vip3Aa39 concentration, was ≤0.0 at concentrations of 0.1-31.6 μg cm-2 . The test using a monogenic mode of inheritance showed that resistance to Vip3Aa in H. zea was largely due to a single gene. CONCLUSION Results of this study indicate that Vip3Aa resistance in H. zea is monogenic, autosomal, and recessive. This information is valuable for studying the mechanism of Vip3Aa resistance, monitoring of resistance development, and designing appropriate strategies for preventive management of Vip3Aa resistance. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | | | - Gregory A Sword
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX, USA
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Extended investigation of field-evolved resistance of the corn earworm Helicoverpa zea(Lepidoptera: Noctuidae) to Bacillus thuringiensis Cry1A.105 and Cry2Ab2 proteins in thesoutheastern United States. J Invertebr Pathol 2021; 183:107560. [PMID: 33631194 DOI: 10.1016/j.jip.2021.107560] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 01/30/2021] [Accepted: 02/12/2021] [Indexed: 12/17/2022]
Abstract
Previous studies have reported that the corn earworm/bollworm, Helicoverpa zea (Boddie), has developed field resistance to pyramided Bacillus thuringiensis (Bt) Cry1A/Cry2A maize and cotton in certain areas of the southeastern United States. The objective of the current study was to determine the current status and distribution of the resistance to Cry1A.105 and Cry2Ab2 in H. zea. In the study, 31 H. zea populations were collected from major maize planting areas across seven southeastern states of the United States during 2018 and 2019 and assayed against the two Bt proteins. Diet over-lay bioassays showed that most of the populations collected during the two years were significantly resistant to the Cry1A.105 protein. Most of the populations collected during 2019 were also resistant to Cry2Ab2, while significant variances were observed in the susceptibility of the populations collected during 2018 to Cry2Ab2. The results showed that Cry1A.105 and Cry2Ab2 resistance in H. zea is widely distributed in the regions sampled. The resistance to Cry1A.105 appeared to have plateaued, while selection for Cry2Ab2 resistance is likely still occurring. Thus, effective measures for mitigating the Cry1A/Cry2A resistance need to be developed and implemented to ensure the sustainable use of Bt crop biotechnology.
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Dively GP, Kuhar TP, Taylor S, Doughty HB, Holmstrom K, Gilrein D, Nault BA, Ingerson-Mahar J, Whalen J, Reisig D, Frank DL, Fleischer SJ, Owens D, Welty C, Reay-Jones FPF, Porter P, Smith JL, Saguez J, Murray S, Wallingford A, Byker H, Jensen B, Burkness E, Hutchison WD, Hamby KA. Sweet Corn Sentinel Monitoring for Lepidopteran Field-Evolved Resistance to Bt Toxins. JOURNAL OF ECONOMIC ENTOMOLOGY 2021; 114:307-319. [PMID: 33274391 DOI: 10.1093/jee/toaa264] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Indexed: 06/12/2023]
Abstract
As part of an insect resistance management plan to preserve Bt transgenic technology, annual monitoring of target pests is mandated to detect susceptibility changes to Bt toxins. Currently Helicoverpa zea (Boddie) monitoring involves investigating unexpected injury in Bt crop fields and collecting larvae from non-Bt host plants for laboratory diet bioassays to determine mortality responses to diagnostic concentrations of Bt toxins. To date, this monitoring approach has not detected any significant change from the known range of baseline susceptibility to Bt toxins, yet practical field-evolved resistance in H. zea populations and numerous occurrences of unexpected injury occur in Bt crops. In this study, we implemented a network of 73 sentinel sweet corn trials, spanning 16 U.S. states and 4 Canadian provinces, for monitoring changes in H. zea susceptibility to Cry and Vip3A toxins by measuring differences in ear damage and larval infestations between isogenic pairs of non-Bt and Bt hybrids over three years. This approach can monitor susceptibility changes and regional differences in other ear-feeding lepidopteran pests. Temporal changes in the field efficacy of each toxin were evidenced by comparing our current results with earlier published studies, including baseline data for each Bt trait when first commercialized. Changes in amount of ear damage showed significant increases in H. zea resistance to Cry toxins and possibly lower susceptibility to Vip3a. Our findings demonstrate that the sentinel plot approach as an in-field screen can effectively monitor phenotypic resistance and document field-evolved resistance in target pest populations, improving resistance monitoring for Bt crops.
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Affiliation(s)
- G P Dively
- Department of Entomology, University of Maryland, College Park, MD
| | - T P Kuhar
- Department of Entomology, Virginia Tech, Blacksburg, VA
| | - S Taylor
- Department of Entomology, Virginia Tech, Suffolk, VA
| | - H B Doughty
- Virginia Tech ESAREC/Entomology, Painter, VA
| | | | - D Gilrein
- LIHREC, Cornell University, Riverhead, NY
| | - B A Nault
- Department of Entomology, Cornell AgriTech, Geneva, NY
| | | | - J Whalen
- Private IPM Consultant, Millington, MD
| | - D Reisig
- Department of Entomology and Plant Pathology, NC State University, Plymouth, NC
| | | | - S J Fleischer
- Department of Entomology, Penn State University, University Park, PA
| | - David Owens
- University of Delaware Cooperative Extension, Carvel REC, Georgetown, DE
| | - C Welty
- Rothenbuhler Lab, Ohio State University, Columbus, OH
| | - F P F Reay-Jones
- Pee Dee Research and Education Center, Clemson University, Florence, SC
| | - P Porter
- Department of Entomology, Texas A&M University, AgriLife Research and Extension Center, Lubbock, TX
| | - J L Smith
- Field Crop Pest Management, University of Guelph, Ridgetown, Ontario, Canada
| | - J Saguez
- CEROM, 740 Chemin Trudeau, Saint-Mathieu-de-Beloeil, Quebec J3G 0E2, Canada
| | - S Murray
- Perennia Food and Agriculture, Kentville, Nova Scotia, Canada
| | - A Wallingford
- University of New Hampshire Cooperative Extension, Durham, NH
| | - H Byker
- Department of Plant Agriculture, University of Guelph, Winchester, Ontario, Canada
| | - B Jensen
- Department of Entomology, University of Wisconsin, Madison, WI
| | - E Burkness
- Department of Entomology, University of Minnesota, St. Paul, MN
| | - W D Hutchison
- Department of Entomology, University of Minnesota, St. Paul, MN
| | - K A Hamby
- Department of Entomology, University of Maryland, College Park, MD
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Niu Y, Oyediran I, Yu W, Lin S, Dimase M, Brown S, Reay-Jones FPF, Cook D, Reisig D, Thrash B, Ni X, Paula-Moraes SV, Zhang Y, Chen JS, Wen Z, Huang F. Populations of Helicoverpa zea (Boddie) in the Southeastern United States are Commonly Resistant to Cry1Ab, but Still Susceptible to Vip3Aa20 Expressed in MIR 162 Corn. Toxins (Basel) 2021; 13:63. [PMID: 33467562 PMCID: PMC7830782 DOI: 10.3390/toxins13010063] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 01/06/2021] [Accepted: 01/12/2021] [Indexed: 01/12/2023] Open
Abstract
The corn earworm, Helicoverpa zea (Boddie), is a major pest targeted by pyramided Bacillus thuringiensis (Bt) corn and cotton in the U.S. Cry1Ab is one of the first insecticidal toxins used in Bt crops, while Vip3A is a relatively new toxin that has recently been incorporated into Cry corn with event MIR 162 and Cry cotton varieties to generate pyramided Bt traits targeting lepidopteran pests including H. zea. The objectives of this study were to determine the current status and distribution of the Cry1Ab resistance, and evaluate the susceptibility to Vip3Aa20 expressed in MIR 162 corn in H. zea in the southeastern U.S. During 2018 and 2019, 32 H. zea populations were collected from non-Bt corn (19 populations), Cry corn (12), and Cry/Vip3A cotton (1) across major corn areas in seven southeastern states of the U.S. Susceptibility of these populations to Cry1Ab and Vip3Aa20 was determined using diet-overlay bioassays. Compared to a known susceptible insect strain, 80% of the field populations were 13- to >150-fold resistant to Cry1Ab, while their response to Vip3Aa20 ranged from >11-fold more susceptible to 9-fold more tolerant. Mean susceptibility to each Bt toxin was not significantly different between the two groups of the populations collected from non-Bt and Bt crops, as well as between the two groups of the populations collected during 2018 and 2019. The results show that resistance to Cry1Ab in H. zea is widely distributed across the region. However, the Cry1Ab-resistant populations are not cross-resistant to Vip3Aa20, and H. zea in the region is still susceptible to the Vip3Aa20 toxin. Vip3Aa20 concentrations between 5 and 10 µg/cm2 may be used as diagnostic concentrations for susceptibility monitoring in future. Additional studies are necessary to elucidate the impact of the selection with Bt corn on resistance evolution in H. zea to Vip3A cotton in the U.S.
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Affiliation(s)
- Ying Niu
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA; (Y.N.); (W.Y.); (S.L.); (M.D.)
| | - Isaac Oyediran
- Syngenta Crop Protection LLC, Research Triangle Park, NC 27709, USA; (I.O.); (Y.Z.); (J.S.C.); (Z.W.)
| | - Wenbo Yu
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA; (Y.N.); (W.Y.); (S.L.); (M.D.)
| | - Shucong Lin
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA; (Y.N.); (W.Y.); (S.L.); (M.D.)
| | - Marcelo Dimase
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA; (Y.N.); (W.Y.); (S.L.); (M.D.)
| | - Sebe Brown
- Dean Lee Research Station, Louisiana State University Agricultural Center, Alexandria, LA 71302, USA;
| | | | - Don Cook
- Delta Research and Extension Center, Mississippi State University, Stoneville, MS 38776, USA;
| | - Dominic Reisig
- Vernon G. James Research and Extension Center, North Carolina State University, Plymouth, NC 27962, USA;
| | - Ben Thrash
- Lonoke Extension Center, University of Arkansas, Lonoke, AR 72086, USA;
| | - Xinzhi Ni
- Crop Genetics and Breeding Research, USDA-ARS, Tifton, GA 3173, USA;
| | - Silvana V. Paula-Moraes
- Entomology & Nematology Department, West Florida Research and Education Center, University of Florida, Jay, FL 32565, USA;
| | - Yan Zhang
- Syngenta Crop Protection LLC, Research Triangle Park, NC 27709, USA; (I.O.); (Y.Z.); (J.S.C.); (Z.W.)
| | - Jeng Shong Chen
- Syngenta Crop Protection LLC, Research Triangle Park, NC 27709, USA; (I.O.); (Y.Z.); (J.S.C.); (Z.W.)
| | - Zhimou Wen
- Syngenta Crop Protection LLC, Research Triangle Park, NC 27709, USA; (I.O.); (Y.Z.); (J.S.C.); (Z.W.)
| | - Fangneng Huang
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA; (Y.N.); (W.Y.); (S.L.); (M.D.)
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Huang F. Dominance and fitness costs of insect resistance to genetically modified Bacillus thuringiensis crops. GM CROPS & FOOD 2021; 12:192-211. [PMID: 33380258 PMCID: PMC7781549 DOI: 10.1080/21645698.2020.1852065] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/12/2020] [Accepted: 11/12/2020] [Indexed: 12/21/2022]
Abstract
Evolution of resistance to genetically modified Bacillus thuringiensis (Bt) crops in pest populations is a major threat to the sustainability of the technology. Incidents of field resistance that have led to control problems of Bt crops or significantly reduced susceptibility of individual Bt proteins in pyramided plants have increased dramatically across the world, especially in recent years. Analysis of globally published data showed that 61.5% and 60.0% of the cases of resistance with major alleles that allowed homozygous resistant genotypes to survival on Bt crops were functionally non-recessive and did not involve fitness costs, respectively. Dominance levels (DFLs) measured on Bt plants ranged from -0.02 to 1.56 with a mean (± sem) of 0.35 ± 0.13 for the 13 cases of single-gene resistance to Bt plants that have been evaluated. Among these, all six cases with field control problems were functionally non-recessive with a mean DFL of 0.63 ± 0.24, which was significantly greater than the DFL (0.11 ± 0.07) of the seven cases without field resistance. In addition, index of fitness costs (IFC) of major resistance was calculated for each case based on the fitness of resistant (R'R') and heterozygous (R'S') genotypes on non-Bt plants divided by the fitness of their susceptible (S'S') counterparts. The estimated IFCs for 15 cases of single-gene resistance were similar for R'R' and R'S', and for the cases with and without field resistance; and the values averaged 1.10 ± 0.12 for R'R' and 1.20 ± 0.18 for R'S'. Limited published data suggest that resistance of insects to dual/multiple-gene Bt crops is likely to be more recessive than the related single-gene resistance, but their IFCs are similar. The quantitative analysis of the global data documents that the prevalence of non-recessive resistance has played an essential role in the widespread evolution of resistance to Bt crops, while the lack of fitness costs is apparently not as critical as the non-recessive resistance. The results suggest that planting of 'high dose' traits is an effective method for Bt crop IRM and more comprehensive management strategies that are also effective for functionally non-recessive resistance should be deployed.
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Affiliation(s)
- Fangneng Huang
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA, USA
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Khan MH, Jander G, Mukhtar Z, Arshad M, Sarwar M, Asad S. Comparison of in Vitro and in Planta Toxicity of Vip3A for Lepidopteran Herbivores. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:2959-2971. [PMID: 33080004 DOI: 10.1093/jee/toaa211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Indexed: 06/11/2023]
Abstract
Agricultural pest infestation is as old as domestication of food crops and contributes a major share to the cost of crop production. In a transgenic pest control approach, plant production of Vip3A, an insecticidal protein from Bacillus thuringiensis, is effective against lepidopteran pests. A synthetic Vip3A gene was evaluated for efficacy against Spodoptera litura Fabricius (Lepidoptera: Noctuidae; cotton leafworm), Spodoptera exigua Hübner (Lepidoptera: Noctuidae; beet armyworm), Spodoptera frugiperda Smith (Lepidoptera: Noctuidae; fall armyworm), Helicoverpa armigera Hübner (Lepidoptera: Noctuidae; cotton bollworm), Helicoverpa zea Boddie (Lepidoptera: Noctuidae; corn earworm), Heliothis virescens Fabricius (Lepidoptera: Noctuidae; tobacco budworm), and Manduca sexta L. (Lepidoptera: Sphingidae; tobacco hornworm) in tobacco. In artificial diet assays, the concentration required to achieve 50% mortality was highest for H. zea followed by H. virescens > S. exigua > H. armigera > M. sexta > S. frugiperda > S. litura. By contrast, in bioassays with detached leaves from Vip3A transgenic tobacco, the time until 50% lethality was M. sexta > H. virescens > S. litura > H. zea > H. armigera > S. exigua. There was no significant correlation between the artificial diet and transgenic plant bioassay results. Notably, the two insect species that are best-adapted for growth on tobacco, M. sexta and H. virescens, showed the greatest time to 50% mortality on Vip3A-transgenic tobacco. Together, our results suggest that artificial diet assays may be a poor predictor of Vip3A efficacy in transgenic plants, lepidopteran species vary in their sensitivity to Vip3A in diet-dependent manner, and host plant adaptation of the targeted herbivores should be considered when designing transgenic plants for pest control.
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Affiliation(s)
- Muhammad Hassaan Khan
- Agricultural Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Pakistan Institute for Engineering and Applied Sciences (PIEAS), Nilore Islamabad, Pakistan
| | | | - Zahid Mukhtar
- Agricultural Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Pakistan Institute for Engineering and Applied Sciences (PIEAS), Nilore Islamabad, Pakistan
| | - Muhammad Arshad
- Agricultural Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Pakistan Institute for Engineering and Applied Sciences (PIEAS), Nilore Islamabad, Pakistan
| | - Muhammad Sarwar
- Agricultural Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Pakistan Institute for Engineering and Applied Sciences (PIEAS), Nilore Islamabad, Pakistan
| | - Shaheen Asad
- Agricultural Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Pakistan Institute for Engineering and Applied Sciences (PIEAS), Nilore Islamabad, Pakistan
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48
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Yang F, Head GP, Price PA, Santiago González JC, Kerns DL. Inheritance of Bacillus thuringiensis Cry2Ab2 protein resistance in Helicoverpa zea (Lepidoptera: Noctuidae). PEST MANAGEMENT SCIENCE 2020; 76:3676-3684. [PMID: 32419321 DOI: 10.1002/ps.5916] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/07/2020] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND The corn earworm, Helicoverpa zea (Boddie), is a major target pest of pyramided Bt corn and cotton in the United States. Field-evolved practical resistance to Cry1 and Cry2 proteins in H. zea has been documented in multiple locations in the United States. Understanding the genetic basis of Bt resistance is essential in developing insect resistance management (IRM) strategies for the sustainable use of the Bt crop technology. In this study, we characterized the genetic bases of Cry2Ab2 resistance in H. zea using diet-overlay bioassays with two different forms of Cry2Ab2 protein. RESULTS Laboratory bioassays using a Cry2Ab2-resistant (RR) strain, a susceptible (SS) strain, as well as cross and backcross strains, revealed that resistance to Cry2Ab2 was autosomally inherited and controlled by more than one locus. In diet bioassays, the dominance of Cry2Ab2 resistance in H. zea varied from incompletely recessive to incompletely dominant across all tested Cry2Ab2 concentrations of either Bt corn leaf powder or solubilized protein. On leaf tissue of TwinLink cotton (expressing Cry1Ab and Cry2Ae), Cry2Ab2 resistance in H. zea was completely dominant. CONCLUSION These results have significant implications for understanding the widespread field-evolved resistance of H. zea against Cry1 and Cry2 proteins in Bt corn and cotton and should be useful in developing effective IRM strategies for H. zea. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | | | | | | | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX, USA
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Carrière Y, Degain BA, Harpold VS, Unnithan GC, Tabashnik BE. Gene Flow Between Bt and Non-Bt Plants in a Seed Mixture Increases Dominance of Resistance to Pyramided Bt Corn in Helicoverpa zea (Lepidoptera: Noctuidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:2041-2051. [PMID: 32582955 DOI: 10.1093/jee/toaa138] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Indexed: 06/11/2023]
Abstract
For delaying evolution of pest resistance to transgenic corn producing Bacillus thuringiensis (Bt) toxins, limited data are available to compare the effectiveness of refuges of non-Bt corn planted in seed mixtures versus blocks. Here we addressed this issue in the ear-feeding pest Helicoverpa zea Boddie by measuring its survival and development in the laboratory on ears from field plots with 90% Cry1A.105 + Cry2Ab corn and 10% non-Bt corn planted in a seed mixture or blocks. We compared a strain of H. zea selected for resistance to Cry1Ac in the laboratory, its parent strain not selected in the laboratory, and their F1 progeny. The relative survival of the F1 progeny and dominance of resistance were higher on ears from Bt plants in the seed mixture than the block. Half of the kernels in ears from non-Bt plants in the seed mixture produced both Cry1A.105 and Cry2Ab. However, survival on ears from non-Bt plants did not differ between the block and seed mixture. In simulations based on the observed survival, resistance to Cry1A.105 + Cry2Ab corn evolved faster with the seed mixture than the blocks, because of the higher dominance of resistance in the seed mixture. Increasing the refuge percentage improved durability of Cry1A.105 + Cry2Ab corn more for the blocks than the seed mixture. These findings imply that, for a given percentage of non-Bt corn, resistance of H. zea and other ear-feeding pests to multi-toxin Bt corn is likely to evolve faster for seed mixtures than blocks.
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Affiliation(s)
- Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ
| | - Ben A Degain
- Department of Entomology, University of Arizona, Tucson, AZ
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Reay-Jones FPF, Bilbo TR, Reisig DD. Decline in Sublethal Effects of Bt Corn on Corn Earworm (Lepidoptera: Noctuidae) Linked to Increasing Levels of Resistance. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:2241-2249. [PMID: 32740662 DOI: 10.1093/jee/toaa163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Indexed: 06/11/2023]
Abstract
As part of an ongoing longitudinal study in North and South Carolina, this study reports the recovery of Helicoverpa zea (Boddie) pupae in field trials with genetically engineered corn, Zea mays L., hybrids that produce insecticidal toxins from Bacillus thuringiensis (Bt) in 2017-2019. In total, 10,400 corn ears were collected, which led to 3,927 H. zea pupae (2,215 in South Carolina and 1,712 in North Carolina). Late-planted corn led to a 3.39-fold increase in recovery of pupae compared to early-planted corn. Bt corn expressing Cry1F + Cry1Ab and Cry1A.105 + Cry2Ab2 had 1.67-fold and 2.51-fold fewer pupae than non-Bt near-isolines, respectively. Only six pupae were recovered from the hybrid expressing Cry1F + Cry1Ab + Vip3Aa20. Averaged across trials, Bt corn expressing either Cry1A.105 + Cry2Ab2 or Cry1F + Cry1Ab significantly reduced pupal weight compared to non-Bt near-isolines in North and South Carolina. Combining our data with a previous study at the same locations (Bilbo et al. 2018), reduction in pupal weight between Bt and non-Bt near-isolines significantly declined from 2014 to 2019 for Cry1Ab + Cry1F in North and South Carolina. This decline in levels of a sublethal effect of Bt corn expressing Cry1Ab + Cry1F on H. zea at both locations is likely correlated with resistance development.
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Affiliation(s)
- Francis P F Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, Florence, SC
| | - Thomas R Bilbo
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, Florence, SC
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, the Vernon G. James Research and Extension Center, Plymouth, NC
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