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Kour S, Khurma U, Brodie G. Ecological Characterisation of Native Isolates of Heterorhabditis indica from Viti Levu, Fiji Islands. J Nematol 2021; 53:e2021-85. [PMID: 34723189 PMCID: PMC8552510 DOI: 10.21307/jofnem-2021-085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Indexed: 11/11/2022] Open
Abstract
Entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae are obligate parasites of soil inhibiting insects. EPNs are being widely researched as promising biocontrol agents for a wide range of agricultural pests. It is known that strains of EPNs isolated from different geographical regions differ in their attributes, such as host-finding ability, host range, infectivity, reproduction, and environmental stress tolerance. A precise knowledge of these factors is therefore an essential pre-requisite for devising successful strategies to use these nematodes in biological control programmes. Thus, ecological characterisation of the EPN Heterorhabditis indica (Rhabditida: Heterorhabditidae) newly isolated and representing the only species of EPN reported from the island of Viti Levu, Fiji was carried out using Galleria mellonella larvae (L) (Pyralidae: Galleriinae) as hosts to allow comparisons between bioassays conducted in different laboratories around the world. Temperature data showed that native isolates of H. indica are warm-adapted nematodes with thermal range for infectivity between 15˚C and 35˚C and can reproduce between 20˚C and 30˚C. They are highly virulent with LC50 values against G. mellonella ranging from 2.8 IJ to 3.8 IJ/larva. However, they showed poor desiccation tolerance and fail to infect hosts in soil with moisture levels below 8%. They showed a moderate level of hypoxic tolerance and can be stored at 15˚C for 4 months. Results also showed great variability within the selected native isolates of H. indica. Beneficial traits for selected isolates were added up to identify a superior candidate. The current study also suggested that the thermal niche breadth for infection can differ among conspecific strains of an EPN species. The results of this experimental study on ecological aspects of these native isolates of H. indica should form a basis for their potential use in biological control of insect pests in Fiji.
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Affiliation(s)
- Sumeet Kour
- School of Agricultural, Geography, Environment Ocean and Natural Science, The University of the South Pacific, Fiji Islands
| | - Uma Khurma
- School of Agricultural, Geography, Environment Ocean and Natural Science, The University of the South Pacific, Fiji Islands
| | - Gilianne Brodie
- Institute of Applied Sciences, The University of the South Pacific, Fiji Islands
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Baniya A, DiGennaro P. Genome announcement of Steinernema khuongi and its associated symbiont from Florida. G3 (BETHESDA, MD.) 2021; 11:6149128. [PMID: 33624756 PMCID: PMC8049438 DOI: 10.1093/g3journal/jkab053] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 02/03/2021] [Indexed: 01/15/2023]
Abstract
Citrus root weevil (Diaprepes abbreviates) causes significant yield loss in citrus, especially in Florida. A promising source of control for this pest is biological control agents, namely, native entomopathogenic nematodes (EPNs) within the genus Steinernema. Two species of endemic EPN in Florida are S. diaparepesi, abundant within the central ridge, and S. khuongi, dominating the flatwood regions of the state. These citrus-growing regions differ significantly in their soil habitats, which impacts the potential success of biological control measures. Although the genome sequence of S. diaprepesi is currently available, the genome sequence of S. khuongi and identity of the symbiotic bacteria is still unknown. Understanding the genomic differences between these two nematodes and their favored habitats can inform successful biological control practices. Here, MiSeq libraries were used to simultaneously sequence and assemble the draft genome of S. khuongi and its associated symbionts. The final draft genome for S. khuongi has 8,794 contigs with a total length of ∼82 Mb, a largest contig of 428,226 bp, and N50 of 46 kb; its BUSCO scores indicate that it is > 86% complete. An associated bacterial genome was assembled with a total length of ∼3.5 Mb, a largest contig at 116,532 bp, and N50 of 17,487 bp. The bacterial genome encoded 3,721 genes, similar to other Xenorhabdus genomes. Comparative genomics identified the symbiotic bacteria of S. khuongi as Xenorhabdus poinarii. These new draft genomes of a host and symbiont can be used as a valuable tool for comparative genomics with other EPNs and its symbionts to understand host range and habitat suitability.
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Affiliation(s)
- Anil Baniya
- Department of Entomology and Nematology, University of Florida, Gainesville, FL 32611, USA
| | - Peter DiGennaro
- Department of Entomology and Nematology, University of Florida, Gainesville, FL 32611, USA
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Steinernema khuongi n. sp. (Panagrolaimomorpha, Steinernematidae), a new entomopathogenic nematode species from Florida, USA. J Helminthol 2018; 93:226-241. [PMID: 29743130 DOI: 10.1017/s0022149x18000081] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In this study, molecular (ribosomal sequence data), morphological and cross-hybridization properties were used to identify a new Steinernema sp. from Florida, USA. Molecular and morphological data provided evidence for placing the novel species into Clade V, or the 'glaseri-group' of Steinernema spp. Within this clade, analysis of sequence data of the rDNA genes, 28S and internal transcribed spacer (ITS), depicted the novel species as a distinctive entity and closely related to S. glaseri and S. cubanum. Additionally, cross-hybridization assays showed that the new species is unable to interbreed with either of the latter two species, reinforcing its uniqueness from a biological species concept standpoint. Key morphological diagnostic characters for S. khuongi n. sp. include the mean morphometric features of the third-stage infective juveniles: total body length (average: 1066 μm), tail length (average: 65 μm), location of the excretory pore (average: 80.5 μm) and the values of c (average: 16.4), D% (average: 60.5), E% (average: 126) and H% (average: 46.6). Additionally, males can be differentiated from S. glaseri and S. cubanum by the values of several ratios: D% (average: 68), E% (average: 323) and SW% (average: 120). The natural distribution of this species in Florida encompasses both natural areas and citrus groves, primarily in shallow groundwater ecoregions designated as 'flatwoods'. The morphological, molecular, phylogenetic and ecological data associated with this nematode support its identity as a new species in the S. glaseri-group.
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Yan X, Lin Y, Huang Z, Han R. Characterisation of biological and biocontrol traits of entomopathogenic nematodes promising for control of striped flea beetle (Phyllotreta striolata). NEMATOLOGY 2018. [DOI: 10.1163/15685411-00003155] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Summary
The biological and biocontrol traits of two entomopathogenic nematode isolates, Steinernema pakistanense 94-1 (Sp94-1) and Heterorhabditis indica 212-2 (Hi212-2), were evaluated. The highest yield of infective juveniles (IJ) in monoxenic sponge culture system for Sp94-1 and Hi212-2 was 3.52 (± 0.45) × 105 and 7.08 (± 0.11) × 105 IJ g−1, respectively. The optimum storage temperature was 25°C for Sp94-1 and 14°C for Hi212-2. Sp94-1 showed greater tolerance to heat exposure and UV radiation, while S. carpocapsae All, a commercial strain, was more resistant to osmotic pressure, desiccation, cold treatment and hypoxia than the other tested isolates. Hi212-2 suppressed the Phyllotreta striolata larvae when applied at 1.5 × 109 IJ ha−1 or higher concentrations, while Sp94-1 suppressed the P. striolata larvae only when applied at 4.5 × 109 IJ ha−1. Our study indicates the possibility of commercialisation of the EPN isolates, and further confirms their efficacy against the P. striolata larvae in the field.
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Affiliation(s)
- Xun Yan
- 1Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Institute of Applied Biological Resources, No. 105 Xingang Road West, Guangzhou, P.R. China
| | - Yinying Lin
- 1Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Institute of Applied Biological Resources, No. 105 Xingang Road West, Guangzhou, P.R. China
| | - Zhenmao Huang
- 2Foshan Xiaonong Eco-Technology Co., Ltd, Nanfeng Road, Leping county, Sanshui District, Foshan, P.R. China
| | - Richou Han
- 1Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Institute of Applied Biological Resources, No. 105 Xingang Road West, Guangzhou, P.R. China
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Heve WK, El-Borai FE, Carrillo D, Duncan LW. Biological control potential of entomopathogenic nematodes for management of Caribbean fruit fly, Anastrepha suspensa Loew (Tephritidae). PEST MANAGEMENT SCIENCE 2017; 73:1220-1228. [PMID: 27717178 DOI: 10.1002/ps.4447] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 09/19/2016] [Accepted: 09/19/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND Caribbean fruit fly (Caribfly) is a serious economic insect pest because of development of larvae that hatch from eggs oviposited into fruits by female adults. This study assessed the virulence of twelve entomopathogenic nematode (EPN) isolates to Caribfly in laboratory bioassays as a starting point toward evaluation of management strategies for the fruit-to-soil-dwelling stages of A. suspensa in fields infested by Caribfly. RESULTS Inoculation of A. suspensa with 1 mL of ca 200 IJs larva-1 killed Caribfly at either larval or pupal stage. Pupae were more resistant to EPN infections than larvae. Adult emergence from inoculated pupae in soil microcosms was significantly lower than that observed in filter paper assays. Longest or largest steinernematids suppressed emergence of more adult Caribfly from pupae in soils, whereas shorter heterorhabditids were more infectious to Caribfly larvae. The highest mortalities of A. suspensa were caused by exotic nematodes Steinernema feltiae and Heterorhabditis bacteriophora, followed by the native Heterorhabditis indica and the exotic Steinernema carpocapsae. CONCLUSION Entomopathogenic nematodes reduced the development of Caribfly larvae and pupae to adult in our bioassays, suggesting that EPNs have potential for biological control of A. suspensa. Future work will assess management strategies, using the virulent EPNs, in orchards infested by A. suspensa. © 2016 Society of Chemical Industry.
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Affiliation(s)
- William K Heve
- Institute of Food and Agricultural Science, University of Florida, Citrus Research and Education Centre, Lake Alfred, FL, USA
| | - Fahiem E El-Borai
- Institute of Food and Agricultural Science, University of Florida, Citrus Research and Education Centre, Lake Alfred, FL, USA
- Plant Protection Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
| | - Daniel Carrillo
- Institute of Food and Agricultural Science, University of Florida, Tropical Research and Education Centre, Homestead, FL, USA
| | - Larry W Duncan
- Institute of Food and Agricultural Science, University of Florida, Citrus Research and Education Centre, Lake Alfred, FL, USA
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Hazir S, Shapiro-Ilan DI, Hazir C, Leite LG, Cakmak I, Olson D. Multifaceted effects of host plants on entomopathogenic nematodes. J Invertebr Pathol 2016; 135:53-9. [PMID: 26896698 DOI: 10.1016/j.jip.2016.02.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 02/08/2016] [Accepted: 02/15/2016] [Indexed: 11/21/2022]
Abstract
The success of parasites can be impacted by multi-trophic interactions. Tritrophic interactions have been observed in parasite-herbivore-host plant systems. Here we investigate aspects of multi-trophic interactions in a system involving an entomopathogenic nematode (EPN), its insect host, and host plant. Novel issues investigated include the impact of tritrophic interactions on nematode foraging behavior, the ability of EPNs to overcome negative tritrophic effects through genetic selection, and interactions with a fourth trophic level (nematode predators). We tested infectivity of the nematode, Steinernema riobrave, to corn earworm larvae (Helicoverpa zea) in three host plants, tobacco, eggplant and tomato. Tobacco reduced nematode virulence and reproduction relative to tomato and eggplant. However, successive selection (5 passages) overcame the deficiency; selected nematodes no longer exhibited reductions in phenotypic traits. Despite the loss in virulence and reproduction nematodes, first passage S. riobrave was more attracted to frass from insects fed tobacco than insects fed on other host plants. Therefore, we hypothesized the reduced virulence and reproduction in S. riobrave infecting tobacco fed insects would be based on a self-medicating tradeoff, such as deterring predation. We tested this hypothesis by assessing predatory success of the mite Sancassania polyphyllae and the springtail Sinella curviseta on nematodes reared on tobacco-fed larvae versus those fed on greater wax moth, Galleria mellonella, tomato fed larvae, or eggplant fed larvae. No advantage was observed in nematodes derived from tobacco fed larvae. In conclusion, our results indicated that insect-host plant diet has an important effect on nematode foraging, infectivity and reproduction. However, negative host plant effects, might be overcome through directed selection. We propose that host plant species should be considered when designing biocontrol programs using EPNs.
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Affiliation(s)
- Selcuk Hazir
- Adnan Menderes University, Faculty of Arts and Sciences, Department of Biology, 09100 Aydin, Turkey; Southeastern Fruit and Tree Nut Research Laboratory, USDA-ARS, Byron, GA 31008, USA.
| | - David I Shapiro-Ilan
- Southeastern Fruit and Tree Nut Research Laboratory, USDA-ARS, Byron, GA 31008, USA.
| | - Canan Hazir
- Adnan Menderes University, Aydin Health Services Vocational School, 09100 Aydin, Turkey; Southeastern Fruit and Tree Nut Research Laboratory, USDA-ARS, Byron, GA 31008, USA
| | - Luis G Leite
- Instituto Biologico, APTA, CP 70, Campinas, SP 13001-970, Brazil; Southeastern Fruit and Tree Nut Research Laboratory, USDA-ARS, Byron, GA 31008, USA
| | - Ibrahim Cakmak
- Adnan Menderes University, Faculty of Agriculture, Department of Plant Protection, 09100 Aydin, Turkey
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Gowda M, Patil J, Mansheppa D, Rangasamy V, Verghese A. Entomopathogenic nematodes: a potential biocontrol agent against eggplant ash weevil Myllocerus subfasciatus Guerin (Coleoptera: Curculionidae). NEMATOLOGY 2016. [DOI: 10.1163/15685411-00002989] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Eggplant ash weevil, Myllocerus subfasciatus, is an important pest of eggplant that attacks other solanaceous crops in Asia and Southeast Asia. The potential efficacy of two species of entomopathogenic nematodes (EPN), Steinernema carpocapsae and Heterorhabditis indica, against third instar and pre-pupal stages of this pest was tested under laboratory and poly-greenhouse conditions. In this present study, both stages were susceptible to EPN species but the pre-pupal stage was more susceptible. Steinernema carpocapsae was the most effective species against pre-pupal stages. In a pot experiment, among the EPN species tested, S. carpocapsae caused significantly greater mortality (20-100%) than H. indica (16-92%) against pre-pupal stages and S. carpocapsae caused 16-92% mortality in third instar larvae, while H. indica caused (12-80%) mortality. Both EPN species were able to reproduce in third instar and pre-pupal stages of ash weevil, but progeny production rate for H. indica was significantly higher than those of S. carpocapsae. Our observations also revealed that efficacy of EPN against M. subfasciatus varies with developmental stages of M. subfasciatus and EPN species; therefore, no generalisation can be made. Our findings provide the first insight into the biocontrol potential of S. carpocapsae and H. indica against third instar and pre-pupal stages of M. subfasciatus.
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Affiliation(s)
| | - Jagadeesh Patil
- National Bureau of Agricultural Insect Resources, Bengaluru-560024, India
| | | | | | - Abraham Verghese
- National Bureau of Agricultural Insect Resources, Bengaluru-560024, India
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Zadji L, Baimey H, Afouda L, Moens M, Decraemer W. Effectiveness of different Heterorhabditis isolates from Southern Benin for biocontrol of the subterranean termite, Macrotermes bellicosus (Isoptera: Macrotermitinae), in laboratory trials. NEMATOLOGY 2014. [DOI: 10.1163/15685411-00002749] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The host-finding ability of 28 Heterorhabditis sonorensis isolates and one H. indica isolate from southern Benin and one H. indica isolate from India was examined in vertical migration sand bioassays against workers of a target citrus termite pest, Macrotermes bellicosus. Thereafter, nine selected isolates were subjected to further investigations on virulence. Our results revealed that both H. sonorensis and H. indica isolates exhibit a cruiser type of search strategy and were capable, to various degrees, of migrating, infecting and killing workers of M. bellicosus in sand columns up to 20 cm long over a period of 3 days. However, only three isolates of H. sonorensis caused 100% mortality to M. bellicosus at the greatest depth tested. The exotic H. indica isolate (LN2) did not show strong finding ability compared to the indigenous one. Concerning virulence, differences were observed among isolates for their ability to invade workers of M. bellicosus. After 12 h post exposure, H. sonorensis from Ze (Ze2) and H. sonorensis from Azohoue (Azohoue2) exhibited the lowest invasion time with IT50 = 3.35 and 3.67 h, respectively, and a higher penetration rate (11.4% and 10%, respectively) compared with the other isolates. In the concentration-mortality test, we found that, based on 95% confidence limits, all H. sonorensis and H. indica isolates appeared to be equal, with LC50 values ranging from nine to 16 infected juveniles (IJ) termite−1. Interestingly, 40 IJ termite−1 were enough to cause 80% mortality to M. bellicosus. Contrary to the LC50, the results of our studies clearly demonstrate that M. bellicosus exhibits a time-dependent susceptibility to the tested nematode isolates. So, the lowest LT50 was observed for H. sonorensis Ze2 (LT50 = 23.30 h), the highest for H. sonorensis Yokon (34.76 h). The LT50 of the indigenous H. indica isolate was estimated to 24.07 h. In addition, all selected isolates were able to reproduce in M. bellicosus workers. The highest reproduction potential in M. bellicosus was observed with H. sonorensis Yokon with 20 213 IJ/termite followed by H. sonorensis Ze2 with 19 368 IJ/termites. All tested Beninese EPN isolates were pathogenic to the citrus termite pest M. bellicosus, with H. sonorensis Ze2 being the most virulent.
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Affiliation(s)
- Lionel Zadji
- 1University of Parakou, P.O. Box 123, Parakou Borgou, Benin
- 2Ghent University, Ledeganckstraat 35, 9000 Ghent, Belgium
| | - Hugues Baimey
- 1University of Parakou, P.O. Box 123, Parakou Borgou, Benin
| | - Leonard Afouda
- 1University of Parakou, P.O. Box 123, Parakou Borgou, Benin
| | - Maurice Moens
- 2Ghent University, Ledeganckstraat 35, 9000 Ghent, Belgium
- 3Institute for Agricultural and Fisheries Research (ILVO) Crop Protection Department, Burg. Van Gansberghelaan 96, 9820 Merelbeke, Belgium
| | - Wilfrida Decraemer
- 2Ghent University, Ledeganckstraat 35, 9000 Ghent, Belgium
- 4Royal Belgian Institute of Natural Sciences, Vautierstraat 29, 1000 Brussels, Belgium
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Addis T, Teshome A, Strauch O, Ehlers RU. Life history trait analysis of the entomopathogenic nematode Steinernema riobrave. NEMATOLOGY 2014. [DOI: 10.1163/15685411-00002819] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Life history traits (LHT) of Steinernema riobrave strain Sr 7-12 and Sr HYB19 were assessed at 25°C in monoxenic culture using a hanging drop technique. The LHT were studied with 5 × 109, 10 × 109 and 20 × 109 cells ml−1 of Xenorhabdus cabanillasii in semi-solid Nematode Growth Gelrite. Increased X. cabanillasii densities had a significant positive influence on offspring production on both Sr 7-12 and the hybrid Sr HYB19. At the higher bacterial food density, the total fertility rate (TFR) per female of Sr 7-12 was 2022 offspring and the net reproductive rate () reached 1904 offspring. Similarly, for Sr HYB19, the TFR per female was 2434 and was 1903. The percentage offspring produced via intra-uterine development (endotokia matricida) was relatively higher at 5 × 109 bacterial cells ml−1 than at higher bacterial density, with 64% and 66% of the total offspring produced by Sr 7-12 and Sr HYB19, respectively. A positive correlation () was recorded for offspring production and bacterial food density and for female body volume with bacterial density (). Female nematodes survived longer at higher bacterial food density; however, females of both strains could not survive longer than 7.8 days, beginning from hatching and always ending 1 day after initiation of endotokia matricida. Based on LHT results, there is a potential to maximise yield of dauer juveniles in liquid culture through increasing bacterial food density.
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Affiliation(s)
- Temesgen Addis
- Faculty of Agricultural and Nutritional Sciences, Christian-Albrechts-University, Hermann-Rodewald-Str. 4, 24118 Kiel, Germany
- e∼nema GmbH, Klausdorfer Str. 28-36, D-24223 Schwentinental, Germany
| | - Asmamaw Teshome
- Department of Biology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Olaf Strauch
- e∼nema GmbH, Klausdorfer Str. 28-36, D-24223 Schwentinental, Germany
| | - Ralf-Udo Ehlers
- e∼nema GmbH, Klausdorfer Str. 28-36, D-24223 Schwentinental, Germany
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Navarro PD, McMullen JG, Stock SP. Interactions between the entomopathogenic nematode Heterorhabditis sonorensis (Nematoda: Heterorhabditidae) and the saprobic fungus Fusarium oxysporum (Ascomycota: Hypocreales). J Invertebr Pathol 2013; 115:41-7. [PMID: 24211424 DOI: 10.1016/j.jip.2013.10.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 10/28/2013] [Accepted: 10/29/2013] [Indexed: 10/26/2022]
Abstract
In this study, we assessed the effect of the saprobic fungus, Fusarium oxysporum (Ascomycota: Hypocreales) on the fitness of the entomopathogenic nematode Heterorhabditis sonorensis (Caborca strain). Sand column assays were considered to evaluate the effect of fungal mycelia on infective juvenile (IJ) movement and host access. Additionally, we investigated the effect of fungal spores on the nematodes' ability to search for a host, its virulence, penetration efficiency and reproduction. Three application timings were considered to assess interactions between the fungus and the nematodes. In vitro assays were also considered to determine the effect of fungal extracts on the nematode's symbiotic bacteria. Our observations indicate that presence and age of fungal mycelia significantly affect IJ movement in the sand columns and their ability to establish in the host. These results were also reflected in a reduced insect mortality. In particular, treatments with the 15 days old mycelia showed a significant reduction in insect mortality and penetration efficiency. Presence of fungal spores also impacted nematode virulence and reproduction. In particular, two of the application timings tested (simultaneous [EPN and fungal spores applied at the same time] and alternate I [EPN applied first, fungus applied 24h later]) resulted in antagonistic interactions. Moreover, IJ progeny was reduced to half in the simultaneous application. In vitro assays revealed that fungal extracts at the highest concentration tested (10mg/ml) inhibited the growth of the symbiotic bacteria. Overall, these results suggest that saprobic fungi may play an important role in regulating. EPN populations in the soil, and that they may be one of the factors that impact nematode survival in the soil and their access to insect hosts.
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Affiliation(s)
- P D Navarro
- University of Arizona, Department of Entomology, 1140 E South Campus Dr., Tucson, AZ 85721-0036, USA
| | - J G McMullen
- University of Arizona, Department of Entomology, 1140 E South Campus Dr., Tucson, AZ 85721-0036, USA
| | - S P Stock
- University of Arizona, Department of Entomology, 1140 E South Campus Dr., Tucson, AZ 85721-0036, USA.
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Potential of entomopathogenic nematodes for the control of the banded fruit weevil,Phlyctinus callosus(Schönherr) (Coleoptera: Curculionidae). J Helminthol 2013; 88:293-301. [DOI: 10.1017/s0022149x13000175] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractEntomopathogenic nematodes (EPN) were evaluated for their potential use as biological control agents againstPhlyctinus callosus, the banded fruit weevil (BFW). The susceptibility of larvae and adults to EPN was evaluated using 400 infective juveniles (IJ) per insect after 4 days in 24-well bioassay trays. The nematode isolates used were all able to infect BFW, although the larvae were found to be more susceptible than were the adults. The percentage mortality for BFW larvae ranged from 41 to 73% and for BFW adults from 13 to 45%. The most effective isolate, SF41 ofHeterorhabditis zealandica, was used to investigate the effect of vertical movement of nematodes in sand and sandy loam soil, at specified concentration and temperature. A higher (82.2 ± 0.084%) percentage mortality rate was obtained with the sandy loam soil, than with the use of sand (67.5 ± 0.12%). The LD50and LD90values after 4 days of incubation were 96 and 278 IJ/50 μl, respectively. Nematodes were inactive below 15°C, with the highest mortality of 74 ± 0.081% for BFW larvae recorded at 25°C.Heterorhabditis zealandicawas able to complete its life cycle successfully in sixth-instar BFW larvae after a period of 22 days. The study showed BFW larvae not to be as susceptible to nematode infection as they need a high concentration (400 IJ/larva) and 4 days to give effective control.
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Olfaction shapes host-parasite interactions in parasitic nematodes. Proc Natl Acad Sci U S A 2012; 109:E2324-33. [PMID: 22851767 DOI: 10.1073/pnas.1211436109] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many parasitic nematodes actively seek out hosts in which to complete their lifecycles. Olfaction is thought to play an important role in the host-seeking process, with parasites following a chemical trail toward host-associated odors. However, little is known about the olfactory cues that attract parasitic nematodes to hosts or the behavioral responses these cues elicit. Moreover, what little is known focuses on easily obtainable laboratory hosts rather than on natural or other ecologically relevant hosts. Here we investigate the olfactory responses of six diverse species of entomopathogenic nematodes (EPNs) to seven ecologically relevant potential invertebrate hosts, including one known natural host and other potential hosts collected from the environment. We show that EPNs respond differentially to the odor blends emitted by live potential hosts as well as to individual host-derived odorants. In addition, we show that EPNs use the universal host cue CO(2) as well as host-specific odorants for host location, but the relative importance of CO(2) versus host-specific odorants varies for different parasite-host combinations and for different host-seeking behaviors. We also identified host-derived odorants by gas chromatography-mass spectrometry and found that many of these odorants stimulate host-seeking behaviors in a species-specific manner. Taken together, our results demonstrate that parasitic nematodes have evolved specialized olfactory systems that likely contribute to appropriate host selection.
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Athanassiou CG, Kavallieratos NG, Menti H, Karanastasi E. Mortality of four stored product pests in stored wheat when exposed to doses of three entomopathogenic nematodes. JOURNAL OF ECONOMIC ENTOMOLOGY 2010; 103:977-984. [PMID: 20568646 DOI: 10.1603/ec09202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The insecticidal effect of Heterorhabditis bacteriophora Poinar (Nematoda: Heterorhabditidae), Steinernema carpocapsae (Weiser) (Nematoda: Steinernematidae), and Steinernema feltiae (Filipjev) (Nematoda: Steinernematidae) against Mediterranean flour moth, Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) (larvae), lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) (adults), rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) (adults), and confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) (adults and larvae) was examined under laboratory conditions in wheat, Triticum aestivum L. The nematodes were applied at the following doses: 0 (control), 100, 500, 1,000, 1,500, 5,000, 10,000, and 20,000 infective juveniles (IJs) per ml, corresponding to 10, 50, 100, 150, 500, 1,000, and 2,000 IJs per insect, and their infectivity was tested at 20 and 30 degrees C after 4 and 8 d of exposure. For E. kuehniella larvae wheat treatments with S. feltiae provided mortality that ranged from 36.7 to 78.3% whereas no mortality was noted in the treatment with S. carpocapsae at 100 IJs per ml at 20 or at 30 degrees C. Also, at 20 degrees C, in wheat treated with H. bacteriophora at 100 IJs per ml, very few larvae were dead. For R. dominica adults, at 20 degrees C, the mortality of adults in wheat treated with S. feltiae and S. carpocapsae did not exceed 23.3 and 41.7%, respectively, at 20,000 IJs per ml, with no significant differences among doses. In the case of S. oryzae adults, the mortality was very low at all doses, and temperatures and did not exceed 9%. Mortality of T. confusum adults did not exceed 17% regardless of the entomopathogenic nematode species tested. In contrast, mortality of T. confusum larvae was notably higher and exceeded 56% in wheat treated with 10,000 or 20,000 IJs per ml of S. feltiae at 20 degrees C. Unlike S. feltiae and S. carpocapsae, the application of H. bacteriophora resulted in lower mortality levels. Generally, the increase of temperature reduced the mortality levels of the T. confusum larvae. In most cases, the efficacy level of the tested entomopathogenic nematode species increased with the dose and decreased with the increase of temperature.
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Affiliation(s)
- Christos G Athanassiou
- Laboratory of Entomology and Applied Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Phytokou str., Nea Ionia 38446, Magnissia, Greece
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Subterranean herbivore-induced volatiles released by citrus roots upon feeding by Diaprepes abbreviatus recruit entomopathogenic nematodes. J Chem Ecol 2010; 36:361-8. [PMID: 20309617 DOI: 10.1007/s10886-010-9773-7] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 03/02/2010] [Accepted: 03/05/2010] [Indexed: 10/19/2022]
Abstract
Herbivore-induced volatile emissions benefit plant hosts by recruiting natural enemies of herbivorous insects. Such tritrophic interactions have been examined thoroughly in the above-ground terrestrial environment. Recently, similar signals have also been described in the subterranean environment, which may be of equal importance for indirect plant defense. The larvae of the root weevil, Diaprepes abbreviates, are a serious pest of citrus. Infestations can be controlled by the use of entomopathogenic nematodes, yet the interactions between the plant, insect and nematode are poorly understood and remain unpredictable. In bioassays that used a root zone six-arm olfactometer, citrus roots ('Swingle citrumelo' rootstock) recruited significantly more entomopathogenic nematodes (Steinernema diaprepesi) when infested with root weevil larvae than non-infested roots. Infested plants were more attractive to nematodes than larvae alone. Roots damaged by weevil larvae attracted more nematodes than mechanically damaged roots and sand controls. By dynamic in situ collection and GC-MS analysis of volatiles from soil, we determined that four major terpene compounds were produced by infested plant roots that were not found in samples from non-infested roots or soil that contained only larvae. Solvent extracts of weevil-infested roots attracted more nematodes than extracts of non-infested roots in a two choice sand-column bioassay. These findings suggest that Swingle citrus roots release induced volatiles as an indirect defense in response to herbivore feeding, and that some of these induced volatiles function as attractants for entomopathogenic nematodes.
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Morton A, García-del-Pino F. Ecological characterization of entomopathogenic nematodes isolated in stone fruit orchard soils of Mediterranean areas. J Invertebr Pathol 2009; 102:203-13. [DOI: 10.1016/j.jip.2009.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 08/03/2009] [Accepted: 08/05/2009] [Indexed: 10/20/2022]
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Lacey LA, Shapiro-Ilan DI. Microbial control of insect pests in temperate orchard systems: potential for incorporation into IPM. ANNUAL REVIEW OF ENTOMOLOGY 2008; 53:121-44. [PMID: 17803454 DOI: 10.1146/annurev.ento.53.103106.093419] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Because of their selectivity and safety, microbial control agents (MCAs) appear to be ready-made components of integrated pest management (IPM) systems that do not pose a threat to applicators or the environment and allow other natural enemies to function. Control of several orchard pest insects using MCAs, including viruses, Bacillus thuringiensis, fungi, and entomopathogenic nematodes (EPNs), have been demonstrated in apple, pear, stone fruits, citrus, and several nut crops. B. thuringiensis is the most used MCA for control of lepidopteran orchard pests. Significant use of EPNs in citrus for control of root weevils is also reported. The granulovirus of codling moth is used increasingly in apple and pear by organic growers, with interest also shown by conventional growers. Although some success has been achieved, in most orchard systems MCAs account for a relatively small proportion of the pest control tactics employed, and in some systems they are not used at all. Research toward improving MCA efficacy and economic competitiveness is required to enhance the role of MCAs in IPM.
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Affiliation(s)
- Lawrence A Lacey
- USDA-ARS, Yakima Agriculture Research Laboratory, Wapato, WA 98908, USA.
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