Ovipositional responses of three opiine fruit fly parasitoids (Hymenoptera: Braconidae) to gall-forming tephritids (Diptera: Tephritidae)

In the laboratory, we evaluated ovipositional responses of three insectary-reared opiine parasitoids Diachasmimorpha tryoni (Cameron), Diachasmimorpha longicaudata (Ashmead), and Psyttalia fletcheri (Sivilstri) to galls formed by three nontarget tephritids Eutreta xanthochaeta Aldrich, Procecidochares alani Stekyskal, and Phaeogramma lortnocoibon Asquith. Individual gravid females of the three parasitoids were released onto stems of each gall fly's host plant containing single galls that contained late instar flies, and the parasitoids' oviposition responses were recorded. Although the galls formed by the three nontarget tephritids had similar color (green), shape (spheroid), and size (7-11 mm), responses of the three opiine parasitoids to the galls varied with parasitoid as well as fly species. Thirty-eight and 26% of gravid D. tryoni and D. longicaudata, respectively, probed in E. xanthochaeta galls, which resulted in 28 and 20% of the resident larvae receiving parasitoid eggs. Few (<3%) P. fletcheri probed E. xanthochaeta galls, and no resident larvae received parasitoid eggs. All three species of parasitoids lacked ovipositional response to P. alani and P. lortnocoibon galls; thus, no fly larvae of these two tephritids received any parasitoid eggs. Both D. tryoni and D. longicaudata probed significantly more frequently and for significantly longer periods in lantana stem galls than in nongalled stems. These results indicate that both D. tryoni and D. longicaudata have the ability to recognize E. xanthochaeta galls as potential host microhabitats and fly larvae as hosts. The relevance of these findings to the potential nontarget impacts of opiine fruit fly parasitoids is discussed. (C) 1997 Academic Press.