Is natural enemy distribution compatible with site-specific management of Helicoverpa zea (Lepidoptera: Noctuidae) in sorghum?

Site-specific management of pest insects in agricultural landscapes holds great promise for minimizing yield losses and reducing unwarranted insecticide applications. However, site-specific treatment of pest species may have important non-target impacts on biological control agents due to the tendency of natural enemy populations to show a functional or numerical response to prey density. In grain sorghum, Sorghum bicolor, the corn earworm, Helicoverpa zea (Boddie), is an annual insect pest capable of reducing yields by 10 to 25% at 1-2 larvae per panicle. Statewide, Kansas growers must make corn earworm treatment decisions that not only impact total grain production and profits, but populations of beneficial insects as well. Current sampling strategies for corn earworm in sorghum do not account for larval spatial distributions within an infested field. To date, field data suggest that surrounding land cover type may play an important role in defining corn earworm distribution patterns. While the identification of reduced sampling and treatment area within a field may provide sorghum growers and consultants with time-efficient, site-specific sampling strategies for managing corn earworm in production sorghum fields, the potential use of such a strategy for conserving natural enemies is unknown. The objective of this research was to compare the geospatial distributions of a predator, the insidious flower bug, Orius insidiosus, to the distributions of corn earworm larvae to assess the compatibility of site-specific pest management strategies with the ecological services provided within the sorghum system.