FOLIAR AND SYSTEMIC APPLICATIONS OF NEEM SEED EXTRACT FOR CONTROL OF SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEM.) (LEPIDOPTERA: TORTRICIDAE), INFESTING BLACK AND WHITE SPRUCE SEED ORCHARDS

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Abstract
Neem seed extract (20, 60, and 180 ppm azadirachtin) applied to the crowns of black spruce trees immediately prior to female reproductive bud flush, resulted in high mortality of early instar spruce budworm larvae. Dose-dependent reductions of 40–93%, as compared with check trees, were observed 2 and 4.5 weeks after treatment. Seed cone protection from grazing damage, however, was moderate; at 60 ppm azadirachtin, the incidence of cone grazing was reduced 29%, and the proportion of severely grazed cones reduced 39%, as compared with check trees. Larval mortality and bud damage observed in the laboratory corroborated field results. High toxicity to second-instar larvae, and performance during adverse weather conditions, supports the potential of neem seed extract for control of spruce budworm defoliation. However, both laboratory and field results indicate that feeding occurs before the effects of neem seed extract manifest, resulting in moderate protection of cones. Whereas foliage can tolerate low levels of feeding, female strobili are damaged significantly. Excellent protection of foliage was achieved from systemic injections of neem seed extract to white and black spruce trees (1.5 g azadirachtin/tree). Neem seed extract, formulated for systemic application, could provide a botanical alternative for control of forest pests in urban environments.