Evaluating diverse approaches to enhance the sustainability of rootworm management

Corn rootworm, Diabrotica spp. (Coleoptera: Chrysomelidae), is a serious pest of corn in the United States, causing an estimated $2 billion in economic losses annually. In Iowa, the majority of losses occur from larval feeding on corn roots by western corn rootworm (D. virgifera virgifera LeConte) and northern corn rootworm (D. barberi Smith & Lawrence). Current management for corn rootworm includes crop rotation, soil-applied insecticides, and transgenic corn hybrids. To date, some populations of western and northern corn rootworm have evolved resistance to one or more of these management practices. This research considers additional approaches that may aid in the management of corn rootworm, specifically the use of cover crops and the application of entomopathogenic nematodes (EPN). This project is a multi-year study, at multiple locations, to test the effects of a persistent EPN strain and a winter rye cover crop on rootworm feeding injury and rootworm survival. Furthermore, we are measuring soil properties, including organic matter, nitrate/ammonium, microbial biomass carbon/nitrogen, cation exchange capacity, and texture, to better understand the relationship between EPNs and soil health. Finally, soil samples will be used in baiting tests with greater wax moth larvae, Galleria mellonella (Linnaeus) (Lepidoptera: Pyralidae), to measure the persistence of EPNs in the field. The results from this research may help to increase the ability of farmers to manage this billion-dollar pest.