FOREST ENTOMOLOGY Efficacy of Two Systemic Insecticides Injected Into Loblolly Pine for Protection Against Southern Pine Bark Beetles (Coleoptera: Curculionidae)

Weevaluated the efÞcacy of systemic insecticides emamectin benzoate and Þpronil for preventing mortality of individual loblolly pines, Pinus taeda L., as a result of attacks by southern pine bark beetles (Coleoptera: Curculionidae, Scolytinae) for two consecutive years in Mississippi (2005Ð 2006) and Alabama (2006Ð2007). Trees were injected once in the spring of 2005 (Mississippi) or 2006 (Alabama) and then were baited with species-speciÞc bark beetle lures several weeks later. The southern pine beetle,Dendroctonus frontalis Zimmermann, was the target species but was changed to Ips spp. inMississippi (but not Alabama) the second year because of few southern pine beetle attacks on baited trees. Single injections of emamectin benzoate were effective in reducing tree mortality caused by bark beetles compared with untreated checks. Although less effective overall, Þpronil also signiÞcantly reduced tree mortality from southern pine beetle compared with the checks during the second year in Alabama. Treemortality continuedwell after the lures had been removed. Evaluations of bolts taken from experimental trees killed in 2006 indicated that emamectin benzoate effectively prevented parent bark beetle gallery construction and that Þpronil signiÞcantly reduced lengths of galleries constructed by adult beetles, brood development, and emergence, compared with checks. In contrast, neither insecticide treatment prevented the bark beetles from inoculating blue stain fungi, Ophiostoma spp., into treated trees.