Alternate management strategies for managing phytophagous stink bugs (Hemiptera: Pentatomidae) in cotton in the southeastern USA

Abstract

Practitioners of integrated pest management in cotton have witnessed significant changes in the last several decades. Eradication of the boll weevil, widespread use of selective insecticides, and introduction of genetically modified cotton in the mid-1990s are major factors that have influenced pest management in cotton. A complex of stink bugs, previously controlled coincidently with broad-spectrum insecticides, is now an economically important group of pests in cotton production. The green stink bug, the southern green stink bug, and the brown stink bug infest cotton fields during the reproductive stages; symptoms of stink bug injury to cotton include boll abscission, lint staining, yield loss, and reduced fiber quality. Published research on the management of stink bugs has focused on developing effective sampling procedures, understanding spatial dynamics, and assessing the damage inflicted by the stink bugs. Complementary to the ongoing research on stink bug management at the University of Georgia, the author investigated manipulating planting date on stink bug density and associated boll injury in cotton. Results show that cotton planted in May suffered significantly less boll injury than cotton planted during June. Furthermore, percent boll injury exceeded the Extension recommended treatment threshold more frequently in June-planted cotton than in May-planted cotton. Finally, lint yield and color were deleteriously affected in June-planted cotton. Within-field distribution of boll injury was investigated to understand the spatial dynamics of the pest complex in commercial cotton fields. Using IDW interpolation, variogram analysis, and Moran’s Index, the spatial variability of stink bug injury within fields was demonstrated. Stink bug injury was found to be spatially associated at distances ranging from ~75m to 275m, with an average distance of ~150m. Significant spatial association was observed in 3 out 5 fields studied. The efficacy of whole-field insecticide treatments in commercial fields was compared with a partial insecticide treatment of applying insecticides in alternating strips. Both treatments reduced boll injury significantly compared with the level of damage before treatments. In strip-treated fields, a significant decline in boll injury was observed in untreated strips as well. Based on variogram analysis of boll injury before and after treatments, it was shown that both application strategies disrupted spatial aggregation of stink bugs.