Effect of the Systemic Neonicotinoid Insecticide Dinotefuran on Leaf-level Photosynthesis in Loblolly Pine (Pinus taeda)

Abstract

ABSTRACT Bark beetles (Coleoptera: Curculionidae: Scolytinae) are a common pest in loblolly pine (Pinus taeda L.) plantations, and climate intensification threatens to increase the range of bark beetle infestation and vulnerability of loblolly pine. New insecticides and management options are needed to maintain loblolly pine plantation productivity, mitigating increased bark beetle risk. The systemic neonicotinoid insecticide dinotefuran (Safari 20SG systemic insecticide, Valent USA, LLC), is utilized by nursery managers to protect loblolly pine from bark beetles, but there is little published literature on the insecticide’s potential phytotoxicity. The objective of this study was to evaluate the effect of dinotefuran on the leaf-level photosynthesis of three loblolly pine genotypes. Dinotefuran was applied to lower tree boles, and photosynthetic measurements occurred two months later. Dinotefuran did not significantly impact leaf-level gross photosynthesis (Pgmax), light-saturated net photosynthesis (Pnet) or dark respiration (Rd); nor was there any significant genotypic variation in responses. Dinotefuran appears to be a promising insecticide for bark beetle prevention without risk of foliar toxicity.