scholarly journals Plant defense resistance in natural enemies of a specialist insect herbivore

2019 ◽  
Vol 116 (46) ◽  
pp. 23174-23181 ◽  
Author(s):  
Xi Zhang ◽  
Cong van Doan ◽  
Carla C. M. Arce ◽  
Lingfei Hu ◽  
Sandra Gruenig ◽  
...  
Keyword(s):  
Plant Defense ◽  
Natural Enemies ◽  
Entomopathogenic Nematodes ◽  
Western Corn Rootworm ◽  
Insect Herbivore ◽  
Corn Rootworm ◽  
Biological Control Agents ◽  
Metabolic Resistance ◽  
Evolution Of Resistance ◽  
Specialist Insect

Plants defend themselves against herbivores through the production of toxic and deterrent metabolites. Adapted herbivores can tolerate and sometimes sequester these metabolites, allowing them to feed on defended plants and become toxic to their own enemies. Can herbivore natural enemies overcome sequestered plant defense metabolites to prey on adapted herbivores? To address this question, we studied how entomopathogenic nematodes cope with benzoxazinoid defense metabolites that are produced by grasses and sequestered by a specialist maize herbivore, the western corn rootworm. We find that nematodes from US maize fields in regions in which the western corn rootworm was present over the last 50 y are behaviorally and metabolically resistant to sequestered benzoxazinoids and more infective toward the western corn rootworm than nematodes from other parts of the world. Exposure of a benzoxazinoid-susceptible nematode strain to the western corn rootworm for 5 generations results in higher behavioral and metabolic resistance and benzoxazinoid-dependent infectivity toward the western corn rootworm. Thus, herbivores that are exposed to a plant defense sequestering herbivore can evolve both behavioral and metabolic resistance to plant defense metabolites, and these traits are associated with higher infectivity toward a defense sequestering herbivore. We conclude that plant defense metabolites that are transferred through adapted herbivores may result in the evolution of resistance in herbivore natural enemies. Our study also identifies plant defense resistance as a potential target for the improvement of biological control agents.

scholarly journals Plant defense resistance in natural enemies of a specialist insect herbivore

2019 ◽  
Author(s):  
Xi Zhang ◽  
Cong van Doan ◽  
Carla C.M. Arce ◽  
Lingfei Hu ◽  
Sandra Gruenig ◽  
...  
Keyword(s):  
Plant Defense ◽  
Natural Enemies ◽  
Entomopathogenic Nematodes ◽  
Western Corn Rootworm ◽  
Insect Herbivore ◽  
Corn Rootworm ◽  
Metabolic Resistance ◽  
Evolution Of Resistance ◽  
Specialist Insect ◽  
Novel Target

AbstractPlants defend themselves against herbivores through the production of toxic and deterrent metabolites. Adapted herbivores can tolerate and sequester these metabolites, allowing them to feed on defended plants and become toxic to their own enemies. Can herbivore natural enemies overcome sequestered plant defense metabolites to prey on adapted herbivores? To address this question, we studied how entomopathogenic nematodes cope with benzoxazinoid defense metabolites that are produced by grasses and sequestered by a specialist maize herbivore, the western corn rootworm. We find that nematodes from US maize fields in regions in which the western corn rootworm was present over the last 50 years are behaviorally and metabolically resistant to sequestered benzoxazinoids and more infective towards the western corn rootworm than nematodes from other parts of the world. Exposure of a benzoxazinoid-susceptible nematode strain to the western corn rootworm for five generations results in higher behavioral and metabolic resistance and benzoxazinoid-dependent infectivity towards the western corn rootworm. Thus, herbivores that are exposed to a plant defense sequestering herbivore can evolve both behavioral and metabolic resistance to plant defense metabolites, and these traits are associated with higher infectivity towards a defense sequestering herbivore. We conclude that plant defense metabolites that are transferred through adapted herbivores may result in the evolution of resistance in herbivore natural enemies. Our study also identifies plant defense resistance as a novel target for the improvement of biological control agents.

scholarly journals Calcium-alginate beads as a formulation for the application of entomopathogenic nematodes to control rootworms

2021 ◽  
Author(s):  
Jinwon Kim ◽  
Ivan Hiltpold ◽  
Geoffrey Jaffuel ◽  
Ilham Sbaiti ◽  
Bruce E. Hibbard ◽  
...  
Keyword(s):  
Entomopathogenic Nematodes ◽  
Uv Light ◽  
Diabrotica Virgifera Virgifera ◽  
Alginate Beads ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Diabrotica Virgifera ◽  
Biological Control Agents ◽  
Metabolic Arrest ◽  
Root Feeding

AbstractEntomopathogenic nematodes (EPN) have great potential as biological control agents against root-feeding insects. They have a rapid and long-lasting mode of action, minimal adverse effects on the environment and can be readily mass-produced. However, they have a relatively short shelf-life and are susceptible to desiccation and UV light. These shortcomings may be overcome by encapsulating EPN in Ca2+-alginate hydrogels, which have been shown to provide a humid and UV protective shelter. Yet, current Ca2+-alginate formulations do not keep EPN vigorous and infectious for a prolonged period of time and do not allow for their controlled release upon application. Here, we introduce solid Ca2+-alginate beads which we supplemented with glycerol to better retain the EPN during storage and to ensure a steady release when applied in soil. Glycerol-induced metabolic arrest in EPN (Heterorhabditis bacteriophora) resulting in quiescence and total retainment of EPN when added to beads made with 0.5% sodium alginate and 2% CaCl2·2H2O solutions. More than 4,000 EPN could be embedded in a single 4–5-mm diameter bead, and quiescence could be broken by adding water, after which the EPN readily emerged from the beads. In a field trial, the EPN beads were as effective in reducing root damage by the western corn rootworm (WCR, Diabrotica virgifera virgifera) as EPN that were applied in water. Although further improvements are desirable, we conclude that Ca2+-alginate beads can provide an effective and practical way to apply EPN for the control of WCR larvae.

Evaluation of Trap Cropping and Biological Control Against Southern Corn Rootworm (Coleopetera: Chrysomelidae) in Peanuts

1997 ◽  
Vol 32 (2) ◽  
pp. 229-243 ◽  
Author(s):  
M.E. Barbercheck ◽  
W.C. Warrick
Keyword(s):  
Biological Control ◽  
Entomopathogenic Nematodes ◽  
Field Trials ◽  
Corn Rootworm ◽  
Cucurbita Maxima ◽  
Biological Control Agents ◽  
Trap Crop ◽  
Diabrotica Undecimpunctata Howardi ◽  
Southern Corn Rootworm ◽  
Trap Cropping

Field trials to test the efficacy of trap cropping and biological control for the management of Diabrotica undecimpunctata howardi Barber (Chrysomelidae: Luperini) in peanuts were conducted in 1992, 1993, and 1994. Cucurbita maxima Duchesne cv. ‘Blue Hubbard’ was used as a trap crop for adult beetles and the entomopathogenic nematodes, Steinernema carpocapse Weiser and Steinernema riobravis Cabanillas, Poinar and Raulston, were used as biological control agents against soil-inhabiting larvae. In 1992, peanut yields were highest in treatments that included a trap crop. Trap crop did not affect yield in 1993 or 1994. In 2 out of the 3 years, distribution of pod damage relative to the trap crop suggested that beetles oviposited more frequently in peanuts growing in the row next to the trap crop than in peanuts 3 rows from the trap crop. Although entomopathogenic nematodes persisted for a sufficient period to overlap with the presence of rootworms, they did not affect yield or pod damage in peanuts.

scholarly journals The possibility of using entomopathogenic nematodes and entomophages as bioagents of the western corn rootworm (Diabrotica virgifera virgifera Le Conte)

2018 ◽  
pp. 191-197
Author(s):  
A. Sikura ◽  
V. Gunchak
Keyword(s):  
Entomopathogenic Nematodes ◽  
Diabrotica Virgifera Virgifera ◽  
Biological Agents ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Diabrotica Virgifera

The article presents the results of studies on the possibility of using entomopathogenic nematodes and entomophages against the western corn rootworm. It is established that the bioagents under study are able to regulate the number of Diabrotica virgifera virgifera Le Conte. The obtained results showed the prospects of using these biological agents for phytophage control.

scholarly journals Screening of entomopathogenic nematodes for virulence against the invasive western corn rootworm, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) in Europe

2005 ◽  
Vol 95 (5) ◽  
pp. 473-482 ◽  
Author(s):  
S. Toepfer ◽  
C. Gueldenzoph ◽  
R.-U. Ehlers ◽  
U. Kuhlmann
Keyword(s):  
Biological Control ◽  
Entomopathogenic Nematode ◽  
Larval Mortality ◽  
Nematode Species ◽  
Diabrotica Virgifera Virgifera ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Diabrotica Virgifera ◽  
Biological Control Agents ◽  
Steinernema Glaseri

AbstractEntomopathogenic nematode species available in Europe were screened for their efficacy against both the root-feeding larvae and silk-feeding adults of the western corn rootworm, Diabrotica virgifera virgifera LeConte. Laboratory screening tests were aimed at the selection of candidate biological control agents for the management of this invasive alien pest in Europe. Steinernema glaseri, S. arenarium, S. abassi, S. bicornutum, S. feltiae, S. kraussei, S. carpocapsae and Heterorhabditis bacteriophora were studied to determine their virulence against third instar larvae and adults of D. v. virgifera in small-volume arenas (using nematode concentrations of 0.5, 0.8, 7.9 and 15.9 infective juveniles cm–2). All nematode species were able to invade and propagate in D. v. virgifera larvae, but adults were rarely infected. At concentrations of 7.9 and 15.9 cm–2, S. glaseri, S. arenarium, S. abassi and H. bacteriophora caused the highest larval mortality of up to 77%. Steinernema bicornutum, S. abassi, S. carpocapsae and H. bacteriophora appeared to have a high propagation level, producing 5970±779, 5595±811, 5341±1177 and 4039±1025 infective juveniles per larva, respectively. Steinernema glaseri, S. arenarium, S. feltiae, S. kraussei and H. bacteriophora were further screened at a concentration of 16.7 nematodes cm–2 against third instar larvae in medium-volume arenas (sand-filled trays with maize plants). Heterorhabditis bacteriophora, S. arenarium and S. feltiae caused the highest larval mortality with 77±16.6%, 67±3.5%, and 57±17.1%, respectively. In a next step, criteria for rating the entomopathogenic nematode species were applied based on results obtained for virulence and propagation, and for current production costs and availability in Europe. These criteria were then rated to determine the potential of the nematodes for further field testing. Results showed the highest potential in H. bacteriophora, followed by S. arenarium and S. feltiae, for further testing as candidate biological control agents.

scholarly journals Evaluation of the Field Efficacy of Heterorhabditis Bacteriophora Poinar (Rhabditida: Heterorhabditidae) and Synthetic Insecticides for the Control of Western Corn Rootworm Larvae

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 202 ◽  
Author(s):  
Špela Modic ◽  
Primož Žigon ◽  
Aleš Kolmanič ◽  
Stanislav Trdan ◽  
Jaka Razinger
Keyword(s):  
Entomopathogenic Nematodes ◽  
Sandy Loam ◽  
Entomopathogenic Nematode ◽  
Insect Pest ◽  
Diabrotica Virgifera Virgifera ◽  
Heterorhabditis Bacteriophora ◽  
Negative Control ◽  
Western Corn Rootworm ◽  
Alcohol Ethoxylate ◽  
Corn Rootworm

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera, Chrysomelidae), is an important insect pest of maize in North America and Central and Eastern Europe. In Central Europe, the larvae emerge in May and its three instars feed intensively on maize roots in June, causing plant lodging that leads to a loss of economic yield. A three-year field experiment (2016–2018) was conducted to compare the effectiveness i) of soil-applied granular insecticide based on the active ingredient tefluthrin, ii) of maize seeds dressed with thiacloprid, and iii) entomopathogenic nematodes Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae, product Dianem) against WCR larvae. An additional treatment with alcohol ethoxylate (i.e., soil conditioner) mixed with entomopathogenic nematodes was performed in 2017 and 2018 to check for any increase of entomopathogenic nematodes’ effectiveness. Field tests were carried out in two fields infested naturally with a WCR pest population, one in Bučečovci (Eastern Slovenia) and the other in Šmartno pri Cerkljah (northern Slovenia), exhibiting dissimilar pedo-climatic conditions and soil pest densities. The treatments were performed in five replicates per experiment in each year. The efficacy of the treatments was very similar at both locations, despite the approximately five-fold lower WCR soil pest densities in northern than in eastern Slovenia, as well as being constant over time. The largest number of WCR beetles was observed in the negative control, followed by that of beetles subjected to thiacloprid treatment (insignificant decrease taking into account the entire three-year dataset). Treatments with tefluthrin (44.1 ± 11.7%), H. bacteriophora (46.2 ± 7.4%), and H. bacteriophora + alcohol ethoxylate (49.2 ± 1.8%) significantly decreased the numbers of emerging beetles. Treatments of thiacloprid, H. bacteriophora, and H. bacteriophora + alcohol ethoxylate additionally led to significantly increased maize plant weights. Furthermore, entomopathogenic nematodes were able to persist in maize fields for almost five months at both experimental locations in silty and sandy loam soils. It was concluded that the control of WCR larvae in maize using the entomopathogenic nematode H. bacteriophora is as effective as a tefluthrin treatment, and could thus offer a sustainable Diabrotica v. virgifera biological control management option in Europe.

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