EFFECT OF SPECIES COMPOSITION ON THE SURVIVAL AND DEVELOPMENT OF WESTERN AND NORTHERN CORN-ROOTWORM (COLEOPTERA, CHRYSOMELIDAE)

The effects of interspecific competition between northern and western corn rootworm larvae were examined under greenhouse conditions. Potted corn seedlings were infested with predetermined (mixed) numbers of em bryonated eggs to determine how interspecific competition would affect survivorship, sex ratio, and developmental time for each species. Sur vivorship of both species declined as population densities of the oppo site species increased. Sex ratios of both species were influenced by the population densities of the opposite species. Females declined as the level of the other species increased. The slope of cumulative adul t emergence was the same for heterogeneous populations and homogeneous populations of each species.