Relationship Between Soybean Maturity Group and the Phenology and Abundance of Stink Bugs (Heteroptera: Pentatomidae): Impact on Yield and Quality

Soybean, Glycine max (L.) Merrill, varieties in maturity groups IV–VIII were sampled weekly for stink bugs from mid-June to mid-October in 1993 and 1994. Plots were either treated with tralomethrin to control stink bugs or left untreated to measure yield and seed quality losses to the pests. In 1993, stink bug populations peaked at 8.3 per 25 sweeps in the Group IV NK S4884 in late-August, 6 wks after the R₄ growth stage (full pod without seeds). As they were declining in the Group IV soybean, populations were rapidly increasing in the later-maturing varieties, reaching population peaks 5 to 6 wks after R₄ in all maturity groups. Population peaks in the later-maturing varieties were higher than in the maturity groups IV and V. Similar seasonal population distributions were observed in 1994, although populations peaked 4 to 6× higher than in 1993. Both Nezara viridula (L.) and Acrosternum hilare (Say) were common in 1993 when populations were relatively low. In 1994, N. viridula was the most abundant species. Euschistus seruus (Say) was present at low population densities both years. Tralomethrin treatments significantly decreased the stink bug damage to seeds. Seed weights and yield also were higher in the treated plots of most varieties. Significant correlations occurred for stink bug population peaks with percentage kernel damage, yield reductions and 100-seed weight reductions.