Japanese beetle (Coleoptera: Scarabaeidae): the effects of azadirachtin on the growth and development of the immature forms [Popillia japonica, economic plants]

Topical applications of azadirachtin, a purified extract from seeds of the Indian neem tree, Azadirachta indica A. Juss, to larvae of the Japanese beetle, Popillia japonica newman, completely disrupted subsequent normal development to the adult stage. Prepupae and newly formed pupae were somewhat less susceptible, but pupae three days old and older were not affected. Calculated LD sub(50) and LD sub(90)'s of topically applied azadirachtin were 0.1 and 0.4 mu g per larva, respectively. Azadirachtin also increased the duration of the immature stages. Larvae treated with 1.6 mu g of azadirachtin, for example, had significantly longer (111%) larval periods than did untreated larvae.