An assessment of tritrophic interactions among Beauveria bassiana, western corn rootworm larvae and corn

Western corn rootworm, Diabrotica virgifera virgifera (LeConte) (Coleoptera: Chrysomelidae), is a serious pest of corn. Western corn rootworm larvae are soil-dwelling pests that feed on the roots of corn plants, which can lead to substantial yield loss. Management approaches such as crop rotation, insecticides, and transgenic Bt corn all have documented cases of resistance, creating a need for additional management tools, including bioinsecticides. Entomopathogenic fungi (EPF), such as Beauveria bassiana, are occur naturally in the soil and have, in some cases, been shown to grow endophytically. Due to its saprophytic and endophytic nature, allowing it to persist in the soil, B. bassiana may be a beneficial tool in managing western corn rootworm. We studied two isolates of B. bassiana and assessed their effects on mortality on western corn rootworm larvae in two assay systems, one containing and one lacking soil. We then evaluated the propensity for B. bassiana to persist in the corn rhizosphere and grow endophytically by treating corn seeds with B. bassiana conidia. Finally, we assessed the mortality of western corn rootworm larvae caused by two isolates of B. bassiana when corn seeds were inoculated with conidia and grown in a mix of field soil and potting medium. The results of this research will provide a better understanding of the interactions between plants, insect pests, and entomopathogenic fungi and how they might be used for pest management.