Location: Pest Management ResearchTitle: Evaluation of the effectiveness of the entomopathogens for the management of wireworms (Coleoptera: Elateridae) on spring wheat) Author
Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/22/2014
Publication Date: 6/2/2014
Publication URL: http://handle.nal.usda.gov/10113/58930
Citation: Reddy, G.P., Tangtrakulwanish, K., Wu, S., Miller, J.H., Ophus, V., Prewett, J., Jaronski, S. 2014. Evaluation of the effectiveness of the entomopathogens for the management of wireworms (Coleoptera: Elateridae) on spring wheat. Journal of Invertebrate Pathology. 120:43–49. DOI 10.1016/j.jip.2014.05.005. Interpretive Summary: Wireworms, larvae of “click” beetles, can be major pests in cereal grains, corn, sugar beet, and potato. These insects feed on plant roots, quickly killing seedlings early in the season, and causing feeding damage of tubers late in the season. There are few efficacious insecticide options available to farmers; none for organic growers. In 2013, two commercial insect pathogenic fungi, and a third fungus, under development by ARS, were evaluated as controls of wireworms in wheat in two locations in north central Montana. The fungi were applied at planting time either as spores coating wheat seed, spores on a granular carrier, or spores in an oil-water emulsion as a soil drench in furrow. The three fungi provided significant plant and yield protection under moderate wireworm pressure, indicating their potential utility in the integrate management of this pest. Application of the fungi as granules or as soil drenches was superior to seed coating, and equivalent to imidacloprid, a systemic neonicotinoid insecticide.
Technical Abstract: Wireworms, the larval stage of click beetles (Coleoptera: Elateridae), are serious soil dwelling pests of small grain, corn, sugar beet and potato crops. Limonius californicus (Mannerheim) and Hypnoidus bicolor (Eschscholtz) are the predominant wireworm species infesting wheat in Montana, particularly in the ‘Golden Triangle’ area of north-central Montana. Wireworm populations in field crops are increasing, but currently available insecticides provide only partial control, and no alternative management tools exist. In the current study, three entomopathogenic fungi were tested for efficacy against wireworms in spring wheat at two field locations (Ledger and Conrad, Montana, USA) in 2013. The fungi (Metarhizium brunneum F52, Beauveria bassiana GHA, and Metarhizium robertsii DWR 346) were evaluated in seed coat, in furrow granular and soil drench applications, in addition to imidacloprid (Gaucho®) in seed treatment, which is currently being used by growers. Wireworm damage in various treatments was evaluated as standing plant counts, wireworm population survey, and grain yield production. Three Fungi applied as formulated granules or as soil drenches, and imidacloprid seed treatment resulted in significantly higher plant stand counts and yields at both locations, than fungus-coated seed treatments and the untreated control. Significant difference was detected among the application methods instead of species of the fungi. All three fungi applied as granules in furrow and in soil drench were paramount to seed-coating treatments in wireworm control, and provided an efficacy comparable or superior to imidacloprid. The fungi used in the current study provided significant plant and yield protection under moderate wireworm pressure, indicating their potential utility in the integrate management of this pest.