BIOLOGY, INITIAL EFFECT, AND DESCRIPTION OF A NEW SPECIES OF PERISTENUS (HYMENOPTERA, BRACONIDAE), A PARASITE OF THE ALFALFA PLANT BUG (HEMIPTERA, MIRIDAE), RECENTLY ESTABLISHED IN THE UNITED-STATES

The alfalfa plant bug, Adelphocoris lineolatus (Goeze), is one of two mirid species that are often abundant on alfalfa in the northeastern United States. We have established the European parasite Peristenus conradi, n. sp., described in this paper, at one site in northern Delaware. Here the parasitism of first-generation alfalfa plant bugs over 3 yr by P. conradi averaged almost-equal-to 4 times more than parasitism by the native Peristenus pallipes (Curtis). Total parasitism by both braconid species was almost-equal-to 50%, so the potential for biocontrol of the alfalfa plant bug, especially in seed alfalfa, is encouraging. P. conradi is univoltine, deuterotokous, and resembles most closely Peristenus rubricollis (Thomson), an arrhenotokous European species. The dissection method was more accurate than rearing for determination of parasite effect.