Field performance of entomopathogenic nematodes for suppression of western corn rootworm (Coleoptera: Chrysoraelidae)

Abstract

Entomopathogenic nematodes, Steinernema carpocapsae (Weiser) (Mexican and All strains) and Heterorhabditis bacteriophora Poinar (Lewiston strain), and terbufos were evaluated as control agents for the western corn rootworm, Diabrotica virgifera virgifera LeConte. Several application methods for the nematodes were tested: a subsurface knife (planting or after planting) or soil surface (single or multiple applications after planting). Terbufos was applied in a band to the soil surface at planting. Tests were conducted with artificially infested populations of the western corn rootworm. S. carpocapsae (Mexican strain) and H. bacteriophora (Lewiston strain) as a single soil surface, after planting treatment of 200,000 nematodes per plant significantly reduced root damage below that of the control and reduced adult emergence equivalent to terbufos. These treatments reduced root damage below the threshold for potential economic loss and adult emergence by 66-98%. Three soil surface, after planting applications with a total of 600,000 nematodes per plant did not decrease root damage or adult emergence as compared with that of a single application at 200,000 nematodes. The All strain of S. carpocapsae as a knifed or soil surface, after planting treatment was ineffective. Studies are needed to evaluate the efficacy of additional nematode species and strains on natural rootworm populations under a set of soil and crop management condition that are representative for maize production.