Effect of different grass and legume combinations on spider (Araneae) and ground beetle (Coleoptera: Carabidae) populations in roadside habitats in the Mississippi Delta

In the Mississippi Delta, roadside vegetation serves as spring habitat for the bollworm, Heliothis zea (Boddie), and tobacco budworm, H. virescens (F.). Predators of Heliothis also are found in this habitat; they include species of spiders and ground beetles. Test plots of two species of grasses, planted with and without ammonia nitrate applications at planting, and both planted in combination with six species of legumes (total of 16 treatments), were established along U.S. Highway 61 in Washington County. Mississippi in the fall of 1984. The effect of the treatments on spiders and ground beetles during March, April, and May 1985 was determined by sampling populations of theses predators with pitfalltraps. Treatments differed little in species diversity or in species dominance for these two groups of predators. None of the treatments had a significant effect on the numbers of ground beetles, lycosid spiders, or total numbers of spiders captured. Consequently, based on their effect on these important groups of beneficial arthropods, none of the treatments was eliminated for possible use as roadside vegetation in the Mississippi Delta to aid in the control of the F1 generation of Heliothis