Translocation and efficacy of a neem-based insecticide in lodgepole pine using Ips pini (Coleoptera : Scolytidae) as an indicator species

Recent research suggests that mountain pine beetles, Dendroctonus ponderosa e Hopkins, may be controlled on pine using systemic applications of extract s from seeds of the neem tree, Azadirachta indica A. Jussieu. We investigat ed the extent of translocation of neem extracts in the bole of lodgepole pi nes, Pinus contora variety latifolia Engelmann. Because attacks by D. ponde rosae do not always occur high on the bole of standing trees, the Dine engr aver, Ips pint Say, was used as an indicator species. A proprietary emulsif iable concentrate formulation of neem seed extract containing 20,000 ppm az adirachtin was applied into a bir;al ave frill around the root collar of lo dgepole Dines. After 1 wk the trees were felled and the logs were baited at 3, 9, and 15 m front the base with the pheromone ispdienol to induce attac k by I. pini, Sis weeks later, bolts were removed from the trees at the bai t positions and held for a further 16 Mk in rearing. At 3 and 9 m from the base. populations of I. pini (emerged and remaining under the bark) were si gnificantly reduced by 87 and 77%, respectively, indicating that the active ingredients translocated at least 9 m up the bole and persisted for Lit le ast 6 wk. Numbers of emergence holes also were significantly reduced by 89, 88. and 63% at 3, 9, and 15 m, suggesting that the translocation extended beyond 9 m. Neem treatment had no impact on gallery construction and attack density, but significantly reduced the number of progeny per egg gallery. Unlike the currently used systemic arsenical, neem extracts would pose no t oxicity to vertebrates and would have a short residual activity in the envi ronment. There would be little chance of resistance developing because of n eem's multiple modes of action and the fact that very few infested trees in a given year would ever be treated.