scholarly journals Entomopathogenic nematodes increase predation success by inducing specific cadaver volatiles that attract healthy herbivores

2018 ◽  
Author(s):  
Xi Zhang ◽  
Ricardo A. R. Machado ◽  
Cong Van Doan ◽  
Carla C. M. Arce ◽  
Lingfei Hu ◽  
...  
Keyword(s):  
Natural Enemies ◽  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Nematode Resistance ◽  
Diabrotica Virgifera Virgifera ◽  
Transmission Efficiency ◽  
Behavioral Changes ◽  
Butylated Hydroxytoluene ◽  
Diabrotica Virgifera ◽  
Infection Rates

ABSTRACTHerbivore natural enemies, including predators, parasitoids and parasites, protect plants by regulating herbivore populations. Some parasites can increase their transmission efficiency by manipulating host behavior. Whether natural enemies can manipulate herbivore behavior to increase top-down control, however, is unknown. Here, we investigate if and how the entomopathogenic nematode Heterorhabditis bacteriophora, an important biocontrol agent, modulates the behavior of the western corn rootworm, Diabrotica virgifera virgifera, a major maize pest, and how these behavioral changes affect the capacity of the nematode to control the rootworm. We found that healthy rootworm larvae are attracted to nematode-infected cadavers shortly before the emergence of the next generation of nematodes. Nematode-infected rootworms release distinct volatile bouquets, including butylated hydroxytoluene (BHT), which attracts rootworms to infected cadavers. In a soil setting, BHT attracts rootworms and reduces nematode resistance, resulting in increased infection rates and rootworm mortality as well as increased nematode reproductive success. Five out of seven tested insect species were found to be attracted to nematode-infected conspecifics, suggesting that attraction of healthy hosts to nematode-infected cadavers is widespread. This study reveals a new facet of the biology of entomopathogenic nematodes that increases their capacity to control a major root pest by increasing the probability of host encounters.

scholarly journals Entomopathogenic nematodes increase predation success by inducing cadaver volatiles that attract healthy herbivores

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Xi Zhang ◽  
Ricardo AR Machado ◽  
Cong Van Doan ◽  
Carla CM Arce ◽  
Lingfei Hu ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Natural Enemies ◽  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Butylated Hydroxytoluene ◽  
Diabrotica Virgifera ◽  
Major Pest ◽  
Herbivore Species ◽  
Species Specific ◽  
Volatile Cues

Herbivore natural enemies protect plants by regulating herbivore populations. Whether they can alter the behavior of their prey to increase predation success is unknown. We investigate if and how infection by the entomopathogenic nematode Heterorhabditis bacteriophora changes the behavior of healthy larvae of the western corn rootworm (Diabrotica virgifera), a major pest of maize. We found that nematode-infected rootworm cadavers are attractive to rootworm larvae, and that this behavior increases nematode reproductive success. Nematode-infected rootworms release distinct volatile bouquets, including the unusual volatile butylated hydroxytoluene (BHT). BHT alone attracts rootworms, and increases nematode reproductive success. A screen of different nematode and herbivore species shows that attraction of healthy hosts to nematode-infected cadavers is widespread and likely involves species-specific volatile cues. This study reveals a new facet of the biology of herbivore natural enemies that boosts their predation success by increasing the probability of host encounters.

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 NATURAL ENEMIES OF HERBIVORES MAINTAIN THEIR BIOLOGICAL CONTROL POTENTIAL UNDER FUTURE CO2, TEMPERATURE AND PRECIPITATION PATTERNS

2020 ◽  
Author(s):  
Cong Van Doan ◽  
Marc Pfander ◽  
Anouk Guyer ◽  
Xi Zhang ◽  
Corina Maurer ◽  
...  
Keyword(s):  
Natural Enemies ◽  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Abiotic Factors ◽  
Parasitoid Wasp ◽  
Wolf Spider ◽  
Climatic Conditions ◽  
Insect Herbivores ◽  
Temperature And Precipitation ◽  
Increased Temperature

ABSTRACTClimate change will profoundly alter the physiology and ecology of plants, insect herbivores and their natural enemies, resulting in strong effects on multitrophic interactions. Yet, manipulative studies that investigate the direct combined impacts of changes in CO2, temperature, and precipitation on this group of organisms remain rare. Here, we assessed how three day exposure to elevated CO2, increased temperature, and decreased precipitation affect the performance and predation success on species from four major groups of natural enemies of insect herbivores: an entomopathogenic nematode, a wolf spider, a ladybug and a parasitoid wasp. Future climatic conditions (RCP 8.5), entailing a 28% decrease in precipitation, a 3.4°C raise in temperature and a 400 ppm increase in CO2 levels, slightly reduced the survival of entomopathogenic nematodes, but had no effect on the survival of other species. Predation success was not negatively affected in any of the tested species, but was even increased for wolf spiders and entomopathogenic nematodes. Factorial manipulation of climate variables revealed a positive effect of reduced soil moisture on nematode infectivity, but not of increased temperature or elevated CO2. These results suggest that natural enemies of herbivores are well adapted to short term changes in climatic conditions and may not suffer from direct negative effects of future climates. These findings provide mechanistic insights that will inform future efforts to disentangle the complex interplay of biotic and abiotic factors that drive climate-dependent changes in multitrophic interaction networks.

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.

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.

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