Parasitism and Predation of Stink Bug 1 Eggs in Soybean and Alfalfa Fields 2

Abstract

Parasitism and predation of the eggs of Acrosternum hilare (Say), Euschistus servus (Say), Euschistus variolarius (Palisot de Veauvois) and Podisus maculiventris (Say) were studied. Small sheets of filter paper, each containing a stink bug egg mass, were placed on soybean and alfalfa plants during June–Sept. 1977 to determine the degree of parasitism and predation. This procedure was modified in 1978 by placing caged stink bugs on the plants until they oviposited, and then removing the cages and bugs. Supplementary parasitism data were obtained by collecting naturally-oviposited pentatomid egg masses from soybeans and other plants. Four species of parasites were recovered, of which Telenomus podisi Ashmead was the predominant egg parasite of all 4 host species studied in soybeans and alfalfa. Trissolcus euschisti (Ashmead) was also recovered from pentatomid eggs collected from soybeans and several other plant species. Chewing predators generally destroyed more pentatomid eggs in each crop than did sucking predators; egg mortality due to sucking predators, however, was more than 7 times greater in alfalfa than in soybeans during 1978. Combined egg mortality due to parasites and predators was lower for A. hilare than for E. servus , E. variolarius , or P. maculiventris .