Factors influencing the aggregative response of the blue willow beetle, Phratora vulgatissima

Crop rotation has traditionally been a valuable method for managing pests, but now a serious insect pest of maize (Diabrotica virgifera virgifera LeConte Coleoptera: Chrysomelidae]) has developed behavioral resistance to rotation. A simple model of adult behavior and population genetics can explain how this resistance may have developed. This general model indicates that evolution may be caused by selection on a single gene for adult movement and that behavioral resistance only develops at high levels of rotation (>80% of plant landscape). In less diverse landscapes, crop rotation selects for the expansion of host preferences (polyphagy) by adults. More diverse landscapes may delay the evolution of resistance to crop rotation depending on the fitness costs and the nature of the genetic system.