Reproductive potential of the parasitic wasp Microplitis rufiventris Kok. (Hym.: Braconidae), reared in hosts treated with chitin synthesis inhibitors

Different developmental stages of Microplitis rufiventris Kok. larvae were each 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-difluorobenzami de] or Lefenuron/Deltanct [O-n-butylO-(2.2-dimethyl-2, 3-dihydrobenzofuran- 7-yl)-N, N'-dimethyl-N-N'-thiodicarbamate] by feeding treated artificial di ets to parasitized Spodoptera littoralis (Boisd.) larvae to evaluate their effects on the reproductive potential of resulting parasitoids. Lefenuron t reatments caused a great reduction in the reproductive ability of either th e host insect or its parasitoid. Ovaries of parasitoid females (1 day old) emerged from Lefenuron/Deltanct treatments contained more ova than those fr om either Lefenuron or controls. Experienced females from Lefenuron/Deltane t treatments deposited significantly more eggs and contained at death more remaining mature oocytes in their calyx and egg-reservoirs. The combination of carbamate insecticide (Deltanet) and chitin-inhibiting growth regulator (Lefenuron) may enhance the reproductive ability of insect parasitoid and may provide a potential means for developing more effective biological cont rol methods against insect pests.