Reproductive potential of the parasitic wasp Microplitis rufiventris (Braconidae; Hymenoptera) reared in hosts treated with chitin synthesis inhibitors

Different larval stages of Microplitis rufiventris Kokujev were exposed to a sublethal dosage (0.4 ppm) of Lefenuron [N-{2, 5-dichloro-4-(1, 1, 2, 3, 3, 3-hexafluoropropoxy)- phenylaminocarbonyl}-2, 6-difluorobenzamide] or Le fenuron (0.2 ppm)/Deltanet (0.2 ppm) [O-n-butyl O-(2, 2-dimethyl-2, 3-dihyd robenzofuran-7-yl)-N, N'-dimethyl-N-N'-thiodicarbamate] by feeding treated artificial diets to parasitized Spodoptera littoralis (Boisduval) larvae to evaluate the effects on the reproductive potential of developing parasitoi ds. Lefenuron treatments caused a reduction in the reproductive ability of either the host insect or its parasitoid. Ovaries of parasitoid females (1 d old) emerging from Lefenuron/Deltanet treatments contained more ova than those From either Lefenuron-treated or control females. Experienced (ovipos iting) females from Lefenuron/Deltanet treatments deposited significantly m ore eggs and contained, at death, more remaining mature oocytes in their ca lyx and egg reservoirs. The combination of a carbamate insecticide (Deltane t) and chitin-inhibiting growth regulator (Lefenuron) may enhance the repro ductive ability of insect parasitoids and may provide a potential means for developing more effective biological control methods against insect pests.