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Duneau D, Sun H, Revah J, San Miguel K, Kunerth HD, Caldas IV, Messer PW, Scott JG, Buchon N. Signatures of Insecticide Selection in the Genome of Drosophila melanogaster. G3 (BETHESDA, MD.) 2018; 8:3469-3480. [PMID: 30190420 PMCID: PMC6222576 DOI: 10.1534/g3.118.200537] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/25/2018] [Indexed: 11/18/2022]
Abstract
Resistance to insecticides has evolved in multiple insect species, leading to increased application rates and even control failures. Understanding the genetic basis of insecticide resistance is fundamental for mitigating its impact on crop production and disease control. We performed a GWAS approach with the Drosophila Genetic Reference Panel (DGRP) to identify the mutations involved in resistance to two widely used classes of insecticides: organophosphates (OPs, parathion) and pyrethroids (deltamethrin). Most variation in parathion resistance was associated with mutations in the target gene Ace, while most variation in deltamethrin resistance was associated with mutations in Cyp6a23, a gene encoding a detoxification enzyme never previously associated with resistance. A "nested GWAS" further revealed the contribution of other loci: Dscam1 and trpl were implicated in resistance to parathion, but only in lines lacking WolbachiaCyp6a17, the paralogous gene of Cyp6a23, and CG7627, an ATP-binding cassette transporter, were implicated in deltamethrin resistance. We observed signatures of recent selective sweeps at all of these resistance loci and confirmed that the soft sweep at Ace is indeed driven by the identified resistance mutations. Analysis of allele frequencies in additional population samples revealed that most resistance mutations are segregating across the globe, but that frequencies can vary substantially among populations. Altogether, our data reveal that the widely used OP and pyrethroid insecticides imposed a strong selection pressure on natural insect populations. However, it remains unclear why, in Drosophila, resistance evolved due to changes in the target site for OPs, but due to a detoxification enzyme for pyrethroids.
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Affiliation(s)
- David Duneau
- Université Toulouse 3 Paul Sabatier, CNRS, ENSFEA; UMR5174 EDB (Laboratoire Évolution & Diversité Biologique); Toulouse, France
| | - Haina Sun
- Department of Entomology, Cornell University, Ithaca, NY 14853
| | - Jonathan Revah
- Department of Entomology, Cornell University, Ithaca, NY 14853
| | - Keri San Miguel
- Department of Entomology, Cornell University, Ithaca, NY 14853
| | - Henry D Kunerth
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, 14853
| | - Ian V Caldas
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, 14853
| | - Philipp W Messer
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, 14853
| | - Jeffrey G Scott
- Department of Entomology, Cornell University, Ithaca, NY 14853
| | - Nicolas Buchon
- Department of Entomology, Cornell University, Ithaca, NY 14853
- Cornell Institute for Host Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, NY 14853
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Pan J, Yang C, Liu Y, Gao Q, Li M, Qiu X. Novel cytochrome P450 (CYP6D1) and voltage sensitive sodium channel (Vssc) alleles of the house fly (Musca domestica) and their roles in pyrethroid resistance. PEST MANAGEMENT SCIENCE 2018; 74:978-986. [PMID: 29155487 DOI: 10.1002/ps.4798] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 11/05/2017] [Accepted: 11/07/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND The house fly Musca domestica is an important disease vector. Point mutation-mediated target-site insensitivity of the voltage sensitive sodium channel (VSSC) and increased detoxification mediated by cytochrome P450 (CYP6D1) overexpression have been characterized as two major mechanisms of pyrethroid resistance. In this study, genetic mutations in the Vssc and CYP6D1 genes and their contribution to pyrethroid resistance were investigated. RESULTS Twelve lines of house flies homozygous for four genotypes were established. House flies carrying the VSSC 1014F mutation and overexpressing CYP6D1 had higher resistance to pyrethroids than those carrying 1014F alone. The presence of the 15-bp insert in the promoter region of the CYP6D1 gene did not necessarily result in a significant increase in CYP6D1 mRNA and pyrethroid resistance levels. A novel Vssc allele carrying two mutations (G1924D and G2004S) in combination with the classic 1014F and a novel CYP6D1 allele that is very similar to CYP6D1v1 were identified in Chinese house flies. CONCLUSION This work demonstrates the effect of genetic mutations in CYP6D1 and Vssc on the susceptibility of house flies to pyrethroids, and verifies that 15-bp insert-containing CYP6D1 alleles have a single origin. These findings offer insights into the evolution of insecticide resistance and have implications for house fly control. © 2017 Society of Chemical Industry.
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Affiliation(s)
- Jing Pan
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chan Yang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yan Liu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qi Gao
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Mei Li
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xinghui Qiu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
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Reduction in Musca domestica fecundity by dsRNA-mediated gene knockdown. PLoS One 2018; 13:e0187353. [PMID: 29342168 PMCID: PMC5771563 DOI: 10.1371/journal.pone.0187353] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/18/2017] [Indexed: 11/20/2022] Open
Abstract
House flies (Musca domestica) are worldwide agricultural pests with estimated control costs at $375 million annually in the U.S. Non-target effects and widespread resistance challenge the efficacy of traditional chemical control. Double stranded RNA (dsRNA) has been suggested as a biopesticide for M. domestica but a phenotypic response due to the induction of the RNAi pathway has not been demonstrated in adults. In this study female house flies were injected with dsRNA targeting actin-5C or ribosomal protein (RP) transcripts RPL26 and RPS6. Ovaries showed highly reduced provisioning and clutch reductions of 94-99% in RP dsRNA treated flies but not in actin-5C or GFP treated flies. Gene expression levels were significantly and specifically reduced in dsRNA injected groups but remained unchanged in the control dsGFP treated group. Furthermore, injections with an Aedes aegypti conspecific dsRNA designed against RPS6 did not impact fecundity, demonstrating species specificity of the RNAi response. Analysis of M. domestica tissues following RPS6 dsRNA injection showed significant reduction of transcript levels in the head, thorax, and abdomen but increased expression in ovarian tissues. This study demonstrates that exogenous dsRNA is specifically effective and has potential efficacy as a highly specific biocontrol intervention in adult house flies. Further work is required to develop effective methods for delivery of dsRNA to adult flies.
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Feng X, Li M, Liu N. Carboxylesterase genes in pyrethroid resistant house flies, Musca domestica. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 92:30-39. [PMID: 29154832 DOI: 10.1016/j.ibmb.2017.11.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 10/23/2017] [Accepted: 11/13/2017] [Indexed: 06/07/2023]
Abstract
Carboxylesterases are one of the major enzyme families involved in the detoxification of pyrethroids. Up-regulation of carboxylesterase genes is thought to be a major component of insecticide resistant mechanisms in insects. Based on the house fly transcriptome and genome database, a total of 39 carboxylesterase genes of different functional clades have been identified in house flies. In this study, eleven of these genes were found to be significantly overexpressed in the resistant ALHF house fly strain compared with susceptible aabys and wild-type CS strains. Eight up-regulated carboxylesterase genes with their expression levels were further induced to a higher level in response to permethrin treatments, indicating that constitutive and inductive overexpression of carboxylesterases are co-responsible for the enhanced detoxification of insecticides. Spatial expression studies revealed these up-regulated genes to be abundantly distributed in fat bodies and genetically mapped on autosome 2 or 3 of house flies, and their expression could be regulated by factors on autosome 1, 2 and 5. Taken together, these results demonstrate that multiple carboxylesterase genes are co-upregulated in resistant house flies, providing further evidence for their involvement in the detoxification of insecticides and development of insecticide resistance.
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Affiliation(s)
- Xuechun Feng
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA
| | - Ming Li
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA; Department of Entomology, University of California, Riverside, CA 92521, USA
| | - Nannan Liu
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA.
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Biale H, Geden CJ, Chiel E. Effects of pyriproxyfen on wild populations of the housefly, Musca domestica, and compatibility with its principal parasitoids. PEST MANAGEMENT SCIENCE 2017; 73:2456-2464. [PMID: 28692174 DOI: 10.1002/ps.4638] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 05/17/2017] [Accepted: 06/06/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND The housefly, Musca domestica L., is an important pest of animal agriculture. Effective fly management requires integration of manure management, mass trapping, biological control, and selective insecticide use. Insecticidal control of houseflies is difficult due to the rapidity of resistance development, yet the insect growth regulator pyriproxyfen (PPF) is one of few insecticides that may still be effective. Here, we tested the susceptibility of wild housefly populations in the USA and in Israel to PPF, as well as the effect of PPF on housefly parasitoids of the genera Muscidifurax and Spalangia. RESULTS Most housefly populations from both countries were completely eliminated at PPF concentrations of 100 mg kg-1 (USA) and 600 mg kg-1 (Israel). One population from each country exhibited initial levels of PPF tolerance. PPF efficacy significantly decreased in cow manure. Emergence rates of parasitoids developing in PPF-treated hosts at concentrations of ≥600 mg kg-1 were significantly affected, whereas other fitness parameters were moderately to non-affected. CONCLUSIONS PPF is still an effective tool for housefly control, but resistance management practices should be employed to avoid resistance. PPF is compatible with principal housefly parasitoids at concentrations <600 mg kg-1 , and is suitable for use in integrated pest management. © 2017 Society of Chemical Industry.
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Affiliation(s)
- Haim Biale
- Department of Biology and Environment, University of Haifa-Oranim, Qiryat Tivon, Israel
- Department of Evolutionary and Environmental Biology, University of Haifa, Haifa, Israel
| | - Christopher J Geden
- USDA, ARS, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL, USA
| | - Elad Chiel
- Department of Biology and Environment, University of Haifa-Oranim, Qiryat Tivon, Israel
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Chen X, Tie M, Chen A, Ma K, Li F, Liang P, Liu Y, Song D, Gao X. Pyrethroid resistance associated with M918 L mutation and detoxifying metabolism in Aphis gossypii from Bt cotton growing regions of China. PEST MANAGEMENT SCIENCE 2017; 73:2353-2359. [PMID: 28544677 DOI: 10.1002/ps.4622] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 05/19/2017] [Accepted: 05/21/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND The cotton aphid, Aphis gossypii (Glover), is a destructive pest that affects numerous crops throughout the world. Pyrethroid resistance has become endemic in A. gossypii populations in the cotton growing areas of China due to wide- spread application of insecticides. To assess the extent of pyrethroid resistance, bioassays were conducted on field populations collected from several cotton cultivation areas from 2010 to 2015. The frequency of a known resistance-associated sodium channel mutation (M918 L) in A. gossypii was evaluated and the bioassay of bifenthrin with or without the synergist was performed to illuminate the mechanisms underlying resistance to pyrethroids. RESULTS The field populations exhibited very high levels of resistance to both beta-cypermethrin and deltamethrin. Pretreatment with synergists, DEF and PBO, significantly increased the toxicity of bifenthrin to cotton aphid populations collected from Bt cotton fields in China. Further, 96.8-100% of individuals with the M918 L mutation (including both RR and RS individuals) were observed in various populations, and only 2.8-3.2% of individuals with wild-type homozygotes (SS) were detected. CONCLUSION The mutation M918 L in the voltage-gated sodium channel along with detoxifying metabolism was contributed to the pyrethroid resistance in the field populations of Aphis gossypii from cotton growing regions of China. And insecticides with different modes of action should be recommended for the control of A. gossypii in the future. © 2017 Society of Chemical Industry.
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Affiliation(s)
- Xuewei Chen
- Department of Entomology, China Agricultural University, Beijing, China
| | - Minyuan Tie
- Department of Entomology, China Agricultural University, Beijing, China
| | - Anqi Chen
- Department of Entomology, China Agricultural University, Beijing, China
| | - Kangsheng Ma
- Department of Entomology, China Agricultural University, Beijing, China
| | - Fen Li
- Department of Entomology, China Agricultural University, Beijing, China
| | - Pingzhuo Liang
- Department of Entomology, China Agricultural University, Beijing, China
| | - Ying Liu
- Department of Entomology, China Agricultural University, Beijing, China
| | - Dunlun Song
- Department of Entomology, China Agricultural University, Beijing, China
| | - Xiwu Gao
- Department of Entomology, China Agricultural University, Beijing, China
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57
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Sun H, Kasai S, Scott JG. Two novel house fly Vssc mutations, D600N and T929I, give rise to new insecticide resistance alleles. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2017; 143:116-121. [PMID: 29183579 DOI: 10.1016/j.pestbp.2017.08.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 08/14/2017] [Accepted: 08/19/2017] [Indexed: 06/07/2023]
Abstract
The house fly, Musca domestica, is a serious pest because it transmits a large diversity of human and veterinary diseases. Insecticides, particularly pyrethroids, are commonly used to control house flies. However, the evolution of pyrethroid resistance has reduced the effectiveness of these insecticides. A major mechanism of resistance to pyrethroids is target site insensitivity caused by the mutations in the voltage-sensitive sodium channel (Vssc) gene (e.g. kdr [L1014F] and super-kdr [M918T+L1014F]). Recently, two novel Vssc alleles, super-kdr+D600N and kdr+T929I were detected in a field collected resistant house fly population in Kansas, USA in 2013. To determine the levels of resistance that these new alleles confer to pyrethroids, we isolated strains having the unique Vssc alleles, but being otherwise congenic to the susceptible strain, aabys. We compared levels of resistance conferred to 14 pyrethroids and determined the inheritance of resistance to 8 pyrethroids. Our results revealed that super-kdr+D600N conferred higher levels of resistance to seven pyrethroids relative to super-kdr, and kdr+T929I showed super-kdr-like levels of resistance in house flies. Our results are compared with previous studies and reveal that addition of T929I to the kdr mutation (L1014F) increased resistance to all pyrethroids (except etofenprox), and enhanced resistance by ~1000-fold to acrinathrin and flumethrin. The implications of these results on the evolution of resistance are discussed.
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Affiliation(s)
- Haina Sun
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA; Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Shinji Kasai
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA; Department of Medical Entomology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjukuku, Tokyo, Japan
| | - Jeffrey G Scott
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA.
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58
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Lorsbach BA, Sparks TC. Innovations in Agrochemical Discovery and the Role of Metabolism, Bioavailability and Formulations. PEST MANAGEMENT SCIENCE 2017; 73:655-657. [PMID: 28247502 DOI: 10.1002/ps.4533] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
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59
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Kasai S, Sun H, Scott JG. Diversity of knockdown resistance alleles in a single house fly population facilitates adaptation to pyrethroid insecticides. INSECT MOLECULAR BIOLOGY 2017; 26:13-24. [PMID: 27792261 DOI: 10.1111/imb.12267] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Insecticide use exerts a tremendous selection force on house fly populations, but the frequencies of the initial resistance mutations may not reach high levels if they have a significant fitness cost in the absence of insecticides. However, with the continued use of the same (or similar) insecticides, it is expected that new mutations (conferring equal or greater resistance, but less of a fitness cost) will evolve. Pyrethroid insecticides target the insect voltage sensitive sodium channel (VSSC) and have been widely used for control of house flies at animal production facilities for more than three decades. There are three Vssc mutations known that cause resistance to pyrethroids in house flies: knockdown resistance (kdr, L1014F), kdr-his (L1014H) and super-kdr (M918T + L1014F). Whether or not there are any new mutations in house fly populations has not been examined for decades. We collected house flies from a dairy in Kansas (USA) and selected this population for three generations. We discovered multiple new Vssc alleles, including two that give very high levels of resistance to most pyrethroids. The importance of these findings to understanding the evolution of insecticide resistance, designing appropriate resistance monitoring and management schemes, and the future of pyrethroids for house fly control are discussed.
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Affiliation(s)
- S Kasai
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA
- Department of Medical Entomology, National Institute of Infectious Diseases, Shinjukuku, Tokyo, Japan
| | - H Sun
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA
- Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - J G Scott
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA
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60
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Concha C, Palavesam A, Guerrero FD, Sagel A, Li F, Osborne JA, Hernandez Y, Pardo T, Quintero G, Vasquez M, Keller GP, Phillips PL, Welch JB, McMillan WO, Skoda SR, Scott MJ. A transgenic male-only strain of the New World screwworm for an improved control program using the sterile insect technique. BMC Biol 2016; 14:72. [PMID: 27576512 PMCID: PMC5004303 DOI: 10.1186/s12915-016-0296-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 08/10/2016] [Indexed: 11/17/2022] Open
Abstract
Background The New World screwworm, Cochliomyia hominivorax, is a devastating pest of livestock endemic to subtropical and tropical regions of the Western hemisphere. The larvae of this species feed on the tissue of living animals, including man, and can cause death if untreated. Over 60 years ago, the sterile insect technique (SIT) was developed with the aim of eradicating this pest, initially from Florida but subsequently from all of North and Central America. From the outset it was appreciated that SIT would be more efficient if only sterile males were released in the field, but this was not possible until now. Results Here, we report on the development and evaluation of the first sexing strains of C. hominivorax that produce only males when raised on diet without tetracycline. Transgenic lines have been developed that possess a tetracycline repressible female-lethal genetic system. Ten of these lines show high female lethality at the late larval/pupal stages and three of them present dominant female lethality. Most of the lines were comparable to the wild type parental strain in several fitness parameters that are relevant to mass rearing in a production facility. Further, three lines performed well in male mating success and male competition assays, suggesting they would be sexually competitive in the field. Consequently, one transgenic line has been selected by the New World Screwworm Program for evaluation under mass rearing conditions. Conclusions We conclude that the promising characteristics of the selected sexing strains may contribute to reduce production costs for the existing eradication program and provide more efficient population suppression, which should make a genetic control program more economical in regions were C. hominivorax remains endemic. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0296-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Carolina Concha
- Department of Entomology, North Carolina State University, Campus Box 7613, Raleigh, NC, 27695-7613, USA.,Panama-United States Commission for the Eradication and Prevention of Screwworm (COPEG), Pacora, Panama.,Smithsonian Tropical Research Institute, Naos Molecular Laboratory, Panama City, Panama
| | - Azhahianambi Palavesam
- USDA-ARS, Tick and Biting Fly Research Unit, Knipling-Bushland Livestock Insects Research Laboratory, 2700 Fredericksburg Rd., Kerrville, TX, 78028, USA.,Present address: Department of Veterinary Parasitology, Madras Veterinary College, Tamil Nadu Veterinary and Animal Sciences University, Chennai, India
| | - Felix D Guerrero
- USDA-ARS, Tick and Biting Fly Research Unit, Knipling-Bushland Livestock Insects Research Laboratory, 2700 Fredericksburg Rd., Kerrville, TX, 78028, USA
| | | | - Fang Li
- Department of Entomology, North Carolina State University, Campus Box 7613, Raleigh, NC, 27695-7613, USA
| | - Jason A Osborne
- Department of Statistics, North Carolina State University, Campus Box 8203, Raleigh, NC, 27695-8203, USA
| | - Yillian Hernandez
- Panama-United States Commission for the Eradication and Prevention of Screwworm (COPEG), Pacora, Panama
| | | | | | | | | | - Pamela L Phillips
- USDA-ARS, Screwworm Research Unit, Pacora, Panama.,USDA-ARS, Screwworm Research Unit, Knipling-Bushland Livestock Insects Research Laboratory, 2700 Fredericksburg Rd., Kerrville, TX, 78028, USA
| | - John B Welch
- USDA-APHIS, IS Action Programs, 2881 F&B Road, College Station, TX, 77845, USA
| | - W Owen McMillan
- Smithsonian Tropical Research Institute, Naos Molecular Laboratory, Panama City, Panama
| | - Steven R Skoda
- USDA-ARS, Screwworm Research Unit, Pacora, Panama.,USDA-ARS, Screwworm Research Unit, Knipling-Bushland Livestock Insects Research Laboratory, 2700 Fredericksburg Rd., Kerrville, TX, 78028, USA
| | - Maxwell J Scott
- Department of Entomology, North Carolina State University, Campus Box 7613, Raleigh, NC, 27695-7613, USA.
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