RELATIONSHIP BETWEEN SOYBEAN MATURITY GROUP AND THE PHENOLOGY AND ABUNDANCE OF STINK BUGS (HETEROPTERA, PENTATOMIDAE) - IMPACT ON YIELD ANDQUALITY

Soybean, Glycine nax (L.) Merrill, varieties in maturity groups IV-VII I were sampled weekly for stink bugs from mid-June to mid-October in 1 993 and 1994. Plots were either treated with tralomethrin to control s tink bugs or left untreated to measure yield and seed quality losses t o the pests. In 1993, stink bug populations peaked at 8.3 per 25 sweep s in the Group IV NK S4884 in late-August, 6 wks after the R(4) growth stage (full pod without seeds). As they were declining in the Group I V soybean, populations were rapidly increasing in the later-maturing v arieties, reaching population peaks 5 to 6 wks after R(4) in all matur ity groups. Population peaks in the later-maturing varieties were high er than in the maturity groups IV and V. Similar seasonal population d istributions were observed in 1994, although populations peaked 4 to 6 X higher than in 1993. Both Nezara viridula (L.) and Acrosternum hilar e (Say) were common in 1993 when populations were relatively low. In 1 994, N. viridula was the most abundant species. Euschistus servus (Say ) was present at low population densities both years. Tralomethrin tre atments significantly decreased the stink bug damage to seeds. Seed we ights and yield also were higher in the treated plots of most varietie s. Significant correlations occurred for stink bug population peaks wi th percentage kernel damage, yield reductions and 100-seed weight redu ctions.