Migratory aphid (Hemiptera : Aphididae) habitat selection in agricultural and adjacent natural habitats

Paired suction traps were used to study the habitat choice of migrating aph ids in adjacent crop and natural habitats in east central Illinois. Traps w ere placed in a row-crop field and a restored prairie for 4 yr at one site, and a row-crop field and a wooded plot for 3 yr at another. Row crops were corn or soybean, rotated annually. We did net wish to sample aphids that w ere native to the local habitats because they would be in a habitat by circ umstance of birth, and not necessarily by choice. We therefore removed fron t the habitat choice analysis any aphid species that colonize plants in eit her the agricultural or natural habitat. Numbers of aphids from outside sou rces in the two adjacent habitats were compared. In 2 of 4 yr, outside-sour ce aphids were more abundant in the row-crop than the restored prairie, des pite the absence of potential host plants in both habitats. In all 3 yr, ou tside-source aphids were trapped in greater numbers in the crop than in the woods. Selection of the crop over the natural habitat occurred during almo st all sampling periods throughout the summers. We present possible explana tions for the aphids' apparent preference for crop habitats and provide bri ef discussions of abundant aphids, local-as well as outside-source species, trapped in our study. We also discuss the relevance of our study to the un derstanding of long- and short-distance aphid migration and aphid vectoring of plant pathogens.