Soybean Cultural Practices: Effects on Populations of Geocorids, Nabids, and Other Soybean Arthropods

Abstract

Arthropods were monitored in soybean, Glycine max L. Merrill, of early-, medium-, and late-maturity groups planted from April through July in several row spacings at four locations in Mississippi for 1 to 3 years. There were four major predator groups at each location: geocorids [mostly Geocoris punctipes (Say)], nabids ( Nabis spp.), lady beetles (Coccinellidae), and spiders. Geocorid, nabid, and spider populations gradually increased during the summer, but lady beetle populations peaked in midseason. Predator populations were not strongly affected by the three cultural practices: Geocorid, nabid, and spider populations (but not lady beetles) were higher in late-planted than in early-planted soybean; nabid populations (but not geocorids, lady beetles, and spiders) were higher in late-maturing than in early-maturing cultivars; and geocorid and spider populations (but not nabids and lady beetles) were higher in narrow- than in wide-row soybean. Predator population responses to cultural practices were generally similar to responses observed among the defoliating caterpillars. The effects of soybean cultural practices on phytophagous beetles and stink bugs are also discussed.