Effects of weed management systems on canopy insects in herbicide-resistant soybeans

The effects of transgenic herbicide-resistant soybean varieties and their c orresponding weed management strategies on canopy insects were examined in studies at two locations in Iowa in 1997 and 1998. Weed management systems that allowed more weed escapes typically had higher insect population densi ties. However, systems with fewer weeds seemingly were preferred by potato leafhoppers. Bean leaf beetles and potato leafhoppers showed preferences fo r certain soybean varieties. but these effects were attributed to soybean p lant height. These findings indicate that although the transgenic soybean v arieties did not strongly affect insect populations, weed management system s can affect insect populations in soybean. However, this impact is likely related more to weed suppression effectiveness than to a direct effect of t he herbicides on the insects.