EFFECT OF NEEM ON THE GROWTH AND DEVELOPMENT OF THE OBLIQUEBANDED LEAFROLLER, CHORISTONEURA-ROSACEANA

Neem, Azadirachta indica A. Juss. (Meliaceae), seed oil (NSO) added to meridic diet at concentrations as low as 0.016% reduced pupation and prevented adult eclosion of obliquebanded leafroller, Choristoneura ro saceana (Harris) (Lepidoptera: Tortricidae). At a rate of 0.0016%, NSO reduced the fitness of C, rosaceana, resulting in longer developmenta l times, lower adult eclosion rates, and reduced egg production compar ed with controls. The neem insecticide Margosan-O (TM) produced compar able results based on concentrations of the most biologically active c onstituent, azadirachtin. Pupation was completely inhibited at concent rations of 0.25% and 1.0% for larvae exposed at 5th or 6th instar, res pectively; rates as low as 0.016% reduced pupal weights and adult eclo sion rates. For larvae transferred to treated diet at 5th instar, phys ical abnormalities in the wings of adults occurred at a rate of 0.004% NSO and increased with increasing treatment rates. NSO at concentrati ons as high as 2.0% was not antifeedant to neonate larvae, based on 24 and 48 h choice test bioassays, when incorporated into a meridic diet .