Potential biological control agents of the Western corn rootworm (Diabrotica virgifera virgifera) in continuous corn of West Central Nebraska

Diabrotica virgifera virgifera, the western corn rootworm (WCR), is a major pest of corn (Zea mays L.) in the U.S. and Europe. Management options include transgenic hybrids, insecticide applications, crop rotation, and other cultural practices. However, WCR’ s high adaptability to control tactics motivated this project to look into alternative options.  In the U.S., little research has been done to investigate the roles of natural enemies of the WCR in commercial fields. Our goal is to identify key natural enemies of irrigated commercial cornfields that can be incorporated as biological control agents as part of an integrated pest management program. We surveyed five cornfields to document populations of WCR, arthropod predators, entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPN). Emergence cages and yellow sticky cards revealed varying levels of WCR populations among fields and an extended WCR emergence period in all fields. Yellow sticky cards also captured a diverse community of above-ground natural enemies but their impact on WCR population dynamics is unlikely. Pitfall traps that captured the ground-dwelling predator community are in the process of being quantified. EPF and EPN were isolated from soil samples using a baiting technique with Galleria mellonella in the lab. EPF and EPN were detected in every field site. Species-level identification of the EPN and EPF are being conducted. Additional studies will be conducted to determine the pathogenicity of these fungi and nematodes towards WCR and assess their potential efficacy as biological control alternatives for the management of this destructive pest.