Yield Loss-Density Relationships of Four Species of Panicle-Feeding Bugs 1 in Sorghum 2

Constant infestation levels of rice stink bug, Oebalus pugnax F., southern green stink bug, Nezara viridula L., conchuela stink bug, ( Chlorochroa ligata Say (Heteroptera: Pentatomidae), or leaffooted bug, Leptoglossus phyllopus L. (Heteroptera: Coreidae), maintained on caged sorghum panicles from the milk, soft-dough and hard-dough stages of grain development to maturity, sometimes caused reductions in yield of grain. The largest reductions in yield occurred when panicles were infested from milk stage to maturity (28 days). No yield reductions occurred when panicles were infested during hard dough, the last 10 days of grain development, at levels up to 16 bugs per panicle. Regression analyses indicated that percent yield reductions increased quadratically as the number of rice stink bugs, southern green stink bugs, conchuela stink bugs, or leaffooted bugs increased per panicle. Equations [E(Y) = bX 2 ] were determined which estimated percent yield losses at different infestation levels for infestations from milk and soft-dough stages to maturity, and these were used to calculate economic injury levels for each species.