Chemical control of the redbay ambrosia beetle

The lethal concentration (LC 90) of 12 commercial insecticides previously tested for control of the Redbay Ambrosia Beetle (RAB), Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae) was determined. Tested pesticides include different formulations of Bifenthrin, Fenpropathrin, Lambda-cyhalothrin + Thiamethoxam, Zeta-cyperthetrhrin + bifenthrin, Methomyl, Chlorpyriphos, Malathion, Permethrin and Carbaryl. Four concentrations of each insecticide were tested (0.5, 0.1, 0.025, 0.005 of the recommended label concentration) and water was used as the control. Probit analysis was used to determine the LC 90.  The lethal concentrations were used to compare the toxicity of the pesticides and select six pesticides to test their persistence under the field conditions during a rainy season in Homestead, FL. Commercial formulations of Bifenthrin, Fenpropathrin, Thiametoxam, z-cyperthetrhrin + bifenthrin, Malathion and Permethrin were applied to avocado trees in a commercial grove. Limbs of treated trees were cut weekly after the application and exposed to RAB to determine the number of beetles boring into the logs. Then, the rainfastness of the most effective pesticide was evaluated in combination with five adjuvants.  In general, the toxicity of pesticides to RAB is greatly reduced two weeks after their application. Among the pesticides registered for use in avocado, Fenpropathrin and Malathion were the most effective protecting trees from attack by RAB. The addition of adjuvants (VaporGard and New Film) improved control of RAB significantly. Other pesticides that are currently not registered for use in Avocados could be useful for managing this beetle.