Azadirachtin is a naturally-occurring insecticide originally isolated from the seeds of A. indica.1 It inhibits feeding behavior, molting, and/or ovarian development in a species-dependent manner in insects.2 Azadirachtin inhibits feeding on G. barbadense leaves and cotyledon disks by third instar H. zea larvae with protection concentrations (PC95s) of 6.2 and 6.8 μg/disk, respectively.3 It inhibits ecdysis and growth of H. zea, H. virescens, S. frugiperda, and P. gossypiella with ecdysis inhibition values (EI95s) ranging from 1 to 10 ppm and ED50 values ranging from 0.4 to 0.7 ppm. Azadirachtin inhibits the growth of freshly molted fourth instar E. varivestis larva (LC50 = 1.66 ppm).2 It is lethal to A. stephensi first, second, third, and fourth instar larva, pupa, and adults at a concentration of 0.1 ppm.4
1.Butterworth, J.H., and Morgan, E.D.Isolation of a substance that suppresses feeding in locustsChem. Commun. (Lond.)123-24(1968) 2.Rembold, H.Azadirachtins. Their structure and mode of actionInsecticides of Plant Origin150-163(1989) 3.Kubo, I., and Kocke, J.A.Azadirachtin, insect ecdysis inhibitorAgr. Biol. Chem.46(7)1951-1953(1982) 4.Nathan, S.S., Kalaivani, K., and Murugan, K.Effects of neem limonoids on the malaria vector Anopheles stephensi Liston (Diptera: Culicidae)Acta. Trop.96(1)47-55(2005)