Evaluation of Biorational Insecticides for Management of Euproctis chrysorrhoea (Lepidoptera: Erebidae)

The browntail moth (Euproctis chrysorrhoea L.) is an invasive species which over the past five years, has been undergoing outbreaks on a scale not seen in the northeastern U.S. in over 100 years. Browntail moth larvae feed on and defoliate a number of deciduous tree species, but the health issues caused by contact with the toxic urticating hairs of the overwintered larvae have resulted in very low tolerance for this pest amongst homeowners and land managers. Few recent studies have been conducted to assess management options for browntail moth, which is abundant in ecologically sensitive areas along coastal waters, and around people's homes. We investigated the potential to manage overwintered larvae with currently available biorational insecticides. Laboratory bioassays revealed susceptibility to Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae), Bacillus thuringiesis kurstaki (Berliner), azadirachtin, and spinosad products. A field trial was conducted to assess efficacy of B. bassiana, Btk, and azadirachtin. All treatments reduced the abundance of larvae compared with the control, but only two applications of Btk and single application of a tank mix of B. bassiana and Btk reduced pupal nest abundance. A laboratory experiment revealed that temperature did not affect the feeding and survival of larvae exposed to the field trial foliage from the Btk and the Btk/B. bassiana tank mix treatments, whereas slower feeding rates and increased time to death were observed with the control and B. bassiana alone treatment.