Evaluation of insecticide residues against spotted lanternfly (Hemiptera: Fulgoridae)

Lycorma delicatula White (Hemiptera: Fulgoridae), spotted lanternfly, is a univoltine, phloem-feeding, polyphagous and invasive insect in the United States. Although a primary host for this species is Ailanthus altissima (Mill.) Swingle, tree of heaven, L. delicatula also feeds on many other plant species, including cultivated grapevines. As this species continues to spread, it is important to develop effective management tools. Here, we evaluated the residual efficacy of 4 insecticides commonly used in tree fruit management programs: dinotefuran, bifenthrin, carbaryl, and thiamethoxam. First, all mobile life stages (early instars, late instars, and adults) of L. delicatula were exposed for 1 h to dry insecticide residues (18 h old) applied to glass or A. altissima bark surfaces. While some mortality was detected immediately following the 1 h exposure period, 100% mortality occurred within 24 h for all materials and life stages exposed on both glass and bark surfaces. To evaluate longer residual activity of these materials, groups of adult L. delicatula were introduced into cages containing A. altissima trees treated with the same individual insecticides and exposed 6 h to residues that were 18 h or 7 days old. Paired, untreated A. altissima served as controls. In these bioassays, 48 h mortality for 18 h old residue reached 95% for thiamethoxam and 100% for bifenthrin and dinotefuran. Seven-day-old bifenthrin and dinotefuran residues again yielded 100% mortality, while thiamethoxam resulted in 58% mortality, and carbaryl yielded only 13.3% and was not significantly different from the control. These results clearly document the efficacy of specific insecticide applications as management tools against L. delicatula.