Effects of Alternative Foods Provided by Living-Mulch on the Life History Traits of the Predatory Bug, Geocoris proteus (Heteroptera: Geocoridae)

Alternative food sources provided by wheat and barley living-mulch were evaluated for the effect on the life history traits of the predatory bug, Geocoris proteus Distant. As alternative food sources, Rhopalosiphum padi (Linnaeus) and Anaphothrips obscurus (Müller) were provided to larvae and adults of G. proteus. Onion thrips, Thrips tabaci Lindeman and a standard food, Ephestia kuehniella (Zeller) eggs served as control food sources. The results showed that R. padi significantly prolonged the larval period and preoviposition period of G. proteus compared to the other prey species. However, R. padi made the female bugs more fecund than T. tabaci, though not so much as the standard food. Anaphothrips obscurus, though less than the standard food, was also nearly equal to T. tabaci in fecundity of the bugs. As a result, R. padi and A. obscurus were superior or nearly equal to T. tabaci in affecting the intrinsic rate of natural increase of G. proteus. These results suggest that wheat and barley would provide preferable alternative foods to G. proteus, thus serving well as living mulch.