Increased plant diversity in an agricultural habitat frequently reduces populations of pest insects. Populations of predators and parasitoids may be more stable and reach higher densities in habitats of greater complexity. This has been attributed to more diverse food resources, improved shelter, and a more favorable microhabitat. Vegetational diversity may also lower insect pest densities by disrupting movement, altering host and prey searching patterns, and masking chemical and visual stimuli. In Maryland, two generalist predators, the anthocorid Orius insidiosus (Say) and the coccinellid Coleomegilla maculata (DeGeer), are the most prevalent and abundant natural enemies of the European corn borer, Ostrinia nubilalis Hübner. High densities of these natural enemies have been observed on buckwheat, Fagopyrum esculentum L., in Maryland. We examined natural enemy densities, European corn borer densities, predation, parasitism, plant injury, and yield in corn plots with and without buckwheat intercropped. We hypothesized that a corn-buckwheat intercropping would increase natural enemy densities, reduce European corn borer densities, reduce plant injury and increase corn yield. Sampling consisted of whole plant visual observations. C. maculata densities increased prior to corn tasseling in the corn-buckwheat intercrop but O. insidiosus densities did not differ between the two treatments. Corn injury from the first generation of European corn borer was reduced in the intercropped treatment. European corn borer tunnel lengths and corn yield did not differ between treatments. Intercropping corn with buckwheat appears to increase the abundance of C. maculata. Small plot size and the low density of European corn borer eggs made it difficult to determine egg predation by C. maculata. Future experiments will correct this deficiency and also focus on C. maculata foraging behavior and mechanisms leading to increased C. maculata densities when buckwheat is present.
Species 1: Coleoptera Coccinellidae Coleomegilla maculata (twelve-spotted lady beetle)
Species 2: Heteroptera Anthocoridae Orius insidiosus (insidious flower bug)
Species 3: Lepidoptera Pyralidae Ostrinia nubilalis (European corn borer)
Keywords: Conservation biological control, Intercropping
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA