Fate of Southern Green Stink-Bug Eggs in Bt-Cotton, Round-up Ready Cotton, Soybeans and Peanuts

There is a need to characterize the mechanisms underlying population dynamics of stink bugs relative to major crops in the southeastern US. To this end, we investigated Southern green stink bug egg mortality by placing sentinel egg masses in plots of soybean, Bt-cotton, Round up Ready (RR) cotton and peanut plants in the Southeast over 2 years. Egg masses were photographed at placement and at various intervals over the subsequent 72 hours to evaluate relative stink bug egg predation and parasitism in the crops. After 72h, surviving egg masses were collected and held in the laboratory to assess parasitism. In 2008, predation of eggs was high in peanuts (74%) and soybeans (65%), and similarly lower in Bt (26%) and RR cotton (21%). Most egg predation in cotton and peanuts was attributable to fire ants, whereas predation in soybeans was due primarily to feeding by long-horned grasshoppers (family Tettigoniidae). Parasitism was low overall but higher in the cotton (8%) than the peanuts (0.17%) and soybeans (2%). Thus, overall egg mortality in cotton was only about half of that observed in soybeans and peanuts. Both predation and parasitism were higher at plot edges than in the centers of all three crops. We are currently analyzing the 2009 data. Future studies will continue to investigate relative egg mortality as well as stink bug reproduction and longevity in the various crops used by these species.