Evaluating Entomopathogens for Control of <i>Melanotus communis</i> (Coleoptera: Elateridae), in Virginia

Abstract

Wireworms represent the subterranean larval stage of click beetles (Coleoptera: Elateridae) and are recognized as economically significant pests affecting root and tuber crops throughout the United States. In the Mid-Atlantic region, the common wireworm, Melanotus communis (Gyllenhal), poses a substantial threat to potato (Solanum tuberosum L.) cultivation. Conventional chemical control strategies, primarily involving broad-spectrum soil insecticides, are increasingly constrained by environmental regulations, non-target effects, and concerns regarding long-term sustainability. Consequently, there is an urgent need for alternative, ecologically informed management strategies. The utilization of naturally occurring entomopathogens formulated as biopesticides provides sustainable options towards Integrated Pest Management (IPM) plans. Accordingly, the objective of this dissertation was to investigate biopesticides for the control of wireworms, specifically M. communis. Entomopathogenic bacteria such as Burkholderia spp. have been registered for managing other soil pests, and preliminary findings from potato field trials in the first study suggest they may also be effective against wireworms. Furthermore, entomopathogenic fungi (EPF) strains within the genera Beauveria spp. and Metarhizium spp. demonstrated pathogenicity towards wireworms. However, the resulting mortality was considerably lower compared to other insect hosts. The final study aimed to evaluate the efficacy of the highest performing EPF strain across various application carriers. The highest average mycosis was seen in rice carrier infected M. communis larvae. The primary aim of this research is to inform the development of IPM frameworks that incorporate biological approaches for the sustainable control of wireworms. Overall, the experimental results indicate that entomopathogenic control agents show some infectivity against M. communis, but larvae display notable resilience. These results will help strengthen biological control of M. communis, thereby contributing to sustainable agroecosystem growth in the Mid-Atlantic region, providing a foundation for future improvement with advancements towards holistic field studies.