INFLUENCE OF WEEDS WITHIN ZEA-MAYS CROP PLANTINGS ON POPULATIONS OF ADULT DIABROTICA-BARBERI AND DIABROTICA-VIRGIFERA-VIRGIFERA

The influence of weeds in corn plantings on abundance of adult Diabrot ica barberi Smith and Lawrence and Diabrotica virgifera virgifera Le C onte (Coleoptera: Chrysomelidae) was examined. Four treatments were es tablished: corn without weeds, corn principally with broadleaf weeds, corn principally with grassy weeds, and corn with a mixture of broadle af and grassy weeds. Significantly greater numbers of D. barberi adult s were collected from corn in treatments with broadleaf weeds than fro m corn in treatments without broadleaf weeds for both years of the stu dy. Relative abundance of adult D. barberi on corn was not significant ly different between treatments containing grassy weeds and treatments without grasses either year. Neither broadleaf nor grassy weeds signi ficantly affected adult populations of D. virgifera virgifera either s eason; however, significantly more western corn rootworm beetles were collected from mixed weeds than from broadleaf or grassy weeds in 1989 . The presence of broadleaf weeds in corn plantings could result in gr eater numbers of D. barberi adults on corn plants, and possibly greate r oviposition.