INHIBITION OF APHID (HOMOPTERA, APHIDIDAE) REPRODUCTION BY NEEM SEED OIL AND AZADIRACHTIN

Exposure of adult green peach aphid, Myzus persicae (Sulzer), and lett uce aphid, Nasonovia ribisnigri (Mosley), for 3 d to a 1.0% solution o f neem seed oil applied to leaf disks reduced the number of live offsp ring by 82 and 66%, respectively, compared with controls. Fourth-insta r N. ribisnigri were more sensitive than adults to the sterilizing act ivity of neem, because they produced 87% fewer offspring than controls following exposure to 1.0% neem seed oil. Exposure to azadirachtin, c onsidered to be the most active component of neem, reduced the fertili ty (live offspring per aphid per day) and the fecundity (live + dead o ffspring per aphid per day) of adult M. persicae, N. ribisnigri, and s trawberry aphid, Chaetosiphon fragaefolii (Cockerell), in a linear, co ncentration-dependant manner. Dissections of treated N. ribisnigri ind icate that exposure to neem seed oil or azadirachtin results in higher mortality rates for embryos just before parturition, but increased mo rtality during this stage does not account for the recorded decrease i n fecundity.