EVALUATION OF NEEM SEED EXTRACT FOR CONTROL OF THE SPRUCE APHID, ELATOBIUM-ABIETINUM (WALKER) (HOMOPTERA, APHIDIDAE)

An extract from seeds of the neem tree, Azadirachta indica A. Juss, en riched with azadirachtin, was evaluated in three experiments for contr ol of the spruce aphid, Elatobium abietinum (Walker), on potted spruce trees in a greenhouse. The extract in Exps. 1 and 2 was first applied in February 1993 when spruce aphid populations were initially low; po pulations were observed weekly for 15 weeks. In Exp. 1, foliar applica tions to the runoff point of 150 ppm azadirachtin applied three times (biweekly) held populations below 5.3 aphids per 6-cm twig samples; po pulations on trees treated at 75 ppm, or with emulsifier only, reached 32.2 and 26.9 aphids per sample, respectively. With five weekly appli cations (Exp. 2), suppression to <14 aphids per sample was achieved wi th both 150- and 75-ppm treatments; populations on control trees peake d at 36.8 aphids per sample. The extract at 150 ppm in Exp. 3 signific antly reduced the number of aphids on trees that initially had high po pulations. The results indicate that neem has potential for operationa l use against aphids in conifer seed orchards.