INSECT GROWTH-REGULATING EFFECTS OF NEEM EXTRACT AND AZADIRACHTIN ON APHIDS

Neem, Azadirachta indica (A. Juss.), seed oil (NSO) applied to leaf di scs at a concentration of 1.0% resulted in 94% to 100% mortality of se cond instar nymphs of currant-lettuce aphid, Nasonovia ribis-nigri (Mo sley), and green peach aphid, Myzus persicae (Sulzer), after nine days . The equivalent amount of pure azadirachtin (AZA) (approximate to 40 ppm), the principle active ingredient of neem, was as effective as NSO . The survival of adult aphids was unaffected by NSO or AZA, but the s urvival of offspring from treated adult M. persicae and N. ribis-nigri was reduced significantly. The lethal concentration of AZA resulting in 50% mortality of second instar nymphs of nine species of aphids ran ged from 2.4 ppm for M. persicae on pepper to 635.0 ppm for the strawb erry aphid, Chaetosiphon fragaefolii (Cockerell), on strawberry. For M . persicae, the growth regulating effect of AZA was influenced by the host plant and the nymphal instar treated.