Efficacy of three insecticides applied to bark to control Agrilus planipennis (Coleoptera: Buprestidae).

Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a serious exotic pest of ash (Fraxinus) trees in North America. In 2003 and 2004, we tested the efficacy of different insecticides sprayed on the bark of cut ash logs for killing emerging EAB adults. Logs (means: length = 30 cm; diam. = 16 cm) were cut from infested ash trees and treated prior to adult emergence. In 2003, we applied imidacloprid at 2 times its label rate to logs 5 days before adults began emerging from logs stored indoors. No adults successfully emerged from the imidacloprid treated logs, while an average of 108 adults per m2 emerged from untreated control logs. In 2004, we tested permethrin and bifenthrin at their label rates, and imidacloprid at its label rate and at 2 times its label rate. Logs (means: length = 25 cm; diam. = 12 cm) infested with EAB and stored outdoors were sprayed once or twice 4-5 wk prior to adult emergence; or once or twice 1-2 wk prior to adult emergence. Overall, mean percent adult mortality was higher for treated logs (90% mortality) compared to control logs (17%). Logs that received two applications had significantly higher mean percent mortality compared with logs that received one application. There was no significant difference in percent adult mortality among the three chemicals tested or between timing of application. In conclusion, permethrin, imidacloprid and bifenthrin were very effective at killing adult EAB emerging from cut logs, and were most effective when applied twice 1-5 wk prior to initial adult emergence.