LONG-TERM EFFECTS OF FENOXYCARB UPON REPRODUCTIVE ACTIVITY AND FECUNDITY IN ADULT FEMALE PERIPLANETA-AMERICANA

Adult, female Periplaneta americana were topically treated with betwee n 1.25-100 mug of fenoxycarb and their reproductive activity was subse quently monitored for 6 months. Doses of greater-than-or-equal-to 2.5 mug of fenoxycarb significantly increased ootheca production for up to 4 weeks, but from about the tenth week onwards these animals tended t o produce fewer oothecae than controls so that the total number of oot hecae laid during the 6 months was not significantly changed by treatm ent. Treatment of insects with 100 mug of fenoxycarb markedly reduced the numbers and weights of nymphs emerging from oothecae laid during t he first 4 weeks after treatment. Hatching and nymph weight were still significantly reduced in oothecae laid 12-13 weeks after treatment, b ut by the end of the 6 months there was no difference from controls. A ll the nymphs successfully moulted into apparently normal second-insta r larvae. Corpora allata were isolated from insects 13 weeks after tre atment with 100 mug of fenoxycarb. When incubated in vitro, they showe d significantly reduced rates of juvenile hormone biosynthesis compare d with glands from control insects.