Location: Fruit and Tree Nut ResearchTitle: Entomopathogenic nematodes and fungi virulence to cowpea curculio (Coleoptera: Curculionidae) larvae
|SCHMIDT, JASON - University Of Georgia|
|Shapiro Ilan, David|
|GRAHAM, CASEY - University Of Georgia|
|BARWICK, SYDNI - University Of Georgia|
|SPARKS JR., ALTON - University Of Georgia|
|RILEY, DAVID - University Of Georgia|
Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2018
Publication Date: 4/30/2018
Citation: Schmidt, J., Shapiro Ilan, D.I., Graham, C., Barwick, S., Sparks Jr., A., Riley, D. 2018. Entomopathogenic nematodes and fungi virulence to cowpea curculio (Coleoptera: Curculionidae) larvae. Journal of Entomological Science. 53(2):152-161. https://doi.org/10.18474/JES17-65.1.
Interpretive Summary: The cowpea curculio is a weevil that can cause major damage to southern peas or cowpeas in the Southeastern United States. Current management recommendations for the cowpea curculio rely on chemical insecticide applications, however insecticide resistance has been observed and efficacy is low for current insecticides. Therefore, safe and environmentally-friendly alternative control solutions must be sought. In a laboratory study, we tested the potential of entomopathogenic (meaning insect-killing) nematodes to cause mortality in the cowpea curculio. These special types of nematodes (also called beneficial nematodes) only kill insects and do not harm humans, plants or the environment. Prior to our tests, beneficial nematodes had not been tested for efficacy against cowpea curculio. We also tested entomopathogenic fungi, which are another kind of environmentally friendly bio-insecticides. We compared the efficacy of four different nematode species and two fungal species to see which ones might be the best at killing cowpea curculio. The nematodes were more virulent in our experiments than the fungi. Also, there were differences among the nematodes (the species that looked most promising are called Heterorhabditis indica and Heterorhabditis bacteriophora). Overall, results indicated that multiple species of nematodes are capable of infecting cowpea curculio, and these data provide the basis for further field tests to examine application of nematodes under field situations.
Technical Abstract: The cowpea curculio, Chalcodermus aeneaus (Boheman), is the major pest of southern peas or cowpea, Vigna unguiculata (L.), throughout the Southeastern United States. Current management recommendations for the cowpea curculio rely on insecticide applications, however insecticide resistance has been observed and efficacy is low for current insecticides. Entomopathogenic biocontrol agents are a possible alternative. In particular, nematodes in the genera Steinernema and Heterorhabditis and fungal entomopathogens Beauveria and Metarhizium. In a first step to provide new environmentally friendly control strategies for the cowpea curculio, laboratory virulence assessments for entomopathogenic agents were conducted. Lower survival rates and higher infection rates were observed for nematodes as compared to fungal pathogens. There were also differences in virulence between nematode species. Results suggested that multiple species of nematodes are capable of infecting cowpea curculio, and these data provide the basis for further field tests to examine the timing of application in field situations.