Entomopathogenic Nematodes and Fungi Virulence to Cowpea Curculio (Coleoptera: Curculionidae) Larvae1

Abstract Cowpea curculio, Chalcodermus aeneus (Boheman), is the major pest of southern peas or cowpea, Vigna unguiculata (L.). Throughout the southeastern United States, current management recommendations for cowpea curculio rely on insecticide applications; however, resistance has been observed. Entomopathogenic biocontrol agents, specifically nematodes in the genera Steinernema and Heterorhabditis and fungi in the genera Beauveria and Metarhizium, have shown efficacy with other curculio pests. We conducted laboratory bioassays to assess the virulence of entomopathogenic agents as a first step to provide alternative control strategies against cowpea curculio. Using controlled environmental conditions, we tested the effects of nematodes (Steinernema carpocapsae Weiser, Steinernema feltiae Filipjev, Heterorhabditis bacteriophora Poinar, and Heterorhabditis indica Poinar) and two fungi (Beauveria bassiana Balsamo and Metarhizium brunneum Petch) on survival and infectivity of cowpea curculio. Heterorhabditis...