Corn Rootworm Oviposition in Soybeans12

Abstract

Twenty-seven fields in Illinois in a soybean-corn rotation were monitored to measure density of rootworm adults in soybeans, oviposition in soybeans, and damage to corn roots the following year. There appears to have been some oviposition by both the northern corn rootworm, Diabrotica longicornis (Say), and the western corn rootworm, D. virgifera LeConte, in nearly all fields, but oviposition and subsequent damage to corn the following year were negligible where soybean fields were virtually free of weeds and volunteer corn. Noneconomic damage occurred when corn followed weedy soybean fields as well as when corn followed nonweedy soybean fields. Highest density of rootworm eggs was found at the base of volunteer corn plants in soybean fields that contained volunteer corn. The greatest root damage occurred in those fields that contained large amounts volunteer corn the previous year.