Effect of volatiles from neem and other natural products on gonotrophic cycle and oviposition of Anopheles stephensi and An-culicifacies (Diptera: Culicidae)

The gonotrophic cycle of female Anopheles was impaired by exposure to volatiles of neem, (Azadirachta indica), reetha, (Sapindus mukorossi), and garlic, (Allium safivum), but not to castor seeds and cotton seed oil. A brief exposure to contact or volatile extracts from neem suppressed rather than inhibited oviposition. Complete inhibition of oviposition was observed by exposure of mosquitoes to neem oil and 1 fraction containing volatile components. Vitellogenesis was impaired irreversably by long-term exposure to neem odor and some extracts. The effect of volatiles on oviposition seems to be regulated by absorption through the cuticle, although passage through the spiracles could not be excluded.