BIOLOGICAL AND MICROBIAL CONTROL Susceptibility of Agrilus planipennis (Coleoptera: Buprestidae) to Beauveria bassiana and Metarhizium anisopliae

The susceptibility of Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) to selected strains of the entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin was evaluated through bioassays with direct immersion or foliar exposureunder laboratoryconditions.Results showed thatA.planipennisadultswere susceptible toB. bassiana andM. anisoplae. SigniÞcant timeÐmortality responsewas found for each isolates. Isolate B. bassianaGHA killed A. planipennis adults at a faster rate compared with other isolates tested, with the lowest average time-to-death values. The LC50 values estimated under direct immersion method ranged from 1.7 10 to 1.9 10, 3.5 10 to 5.3 10, and 4.1 10 to 2.9 10 conidia/ml for B.basissiana and from3.2 10 to 1.1 10, 4.5 10 to 4.5 10, and 1.4 10 to 1.2 10 conidia/ml for M. anisopliae at 4, 5, and 6 d after treatment, respectively. By days 5 and 6, B. bassiana GHA outperformed all other isolates tested except ARSEF 7234, followed by ARSEF 7152, 6393, and 7180. SigniÞcant concentrationÐmortality responsewas also observed for twoB.bassianaGHAformulations, BotaniGard ES and Mycotrol O, and M. anisopliae F52 when insects were treated through foliar exposure. The LC50 values ranged from 114.5 to 309.6, 18.4 to 797.3, and 345.3 to 362.0 conidia/cm 2 for BotaniGard, Mycotrol, andM. anisopliae F52, respectively. Based on the results of these bioassays, the efÞcacy of both B. bassianaGHA formulations andM. anisopliae F52 were similar against adult A. planipennis. The potential use of entomopathogenic fungi for management of A. planipennis in North America is discussed.