Laboratory and field evaluation of hyphomycete insect pathogenic fungi for control of brown citrus aphid (Homoptera: Aphididae)

Single- and multiple-dose bioassays and field trials were conducted to evaluate the efficacy of various isolates of entomopathogenic fungi against the brown citrus aphid, Toxoptera citricida (Kirkaldy). Single-dose bioassays demonstrated that brown citrus aphid is susceptible to several isolates of Beaweria bassiana (Balsamo) Vuillemin, Paecilomyces fumosoroseus (Wize) Brown & Smith, and Metarhizium anisopliae (Metschnikoff) Sorokin. Overt mycosis ranged from 23.1% (M. anisopliae ARSEF759) to 78.0% (B. bassiana SARC 6000). In multiple-dose bioassays, good dose-response was obtained with 3 B. bassiana isolates. The 6-d LD(50) values for these isolates ranged from 119 to 995 conidia per square millimeter. There was a strong correlation (slopes >1.30) between rapid rise in mortality and dosage increase for all 3 isolates. Replicated field trials of the B. bassiana (strain GHA)-based mycoinsecticide Mycotrol ES provided relatively rapid kill at the application rates. The 5-d Abbott percentage efficacies of Mycotrol ES were, respectively, 79.8 and 94.4% at the half and fish rates (2.5 x 10(13) and 5 x 10(13) conidia per hectare). Proportions of overt mycosis ranged from 0.67 at the half rate to 0.80 at the full rate. Mycotrol ES could be an important component of integrated brown citrus aphid management in the future.