The pecan weevil, Curculio caryae (Horn), is a key pest of pecans, Carya illinoinensis (Wangenh.) K. Koch. The entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin are pathogenic to and are being developed as microbial control agents for pecan weevil. One approach to suppressing pest populations and the resultant damage might be to apply entomopathogenic fungi when adult pecan weevils are emerging from the soil. Here we report the efficacy of B. bassiana (GHA strain) and M. anisopliae (F52 strain) applied to trees in orchards at three locations: Byron, GA, Fort Valley, GA, and Comanche, TX. At Fort Valley, treatments included B. bassiana as an oil-based spray with a UV-protective screen applied to the trunk, M. anisopliae applied as an impregnated fiber band stapled onto the trunk, and a nontreated check. At Byron, GA, we compared the B. bassiana trunk treatment to a nontreated check. Treatments at the Texas location were the B. bassiana trunk application, M. anisopliae applied as a trunk band and as a soil drench, and a nontreated check. At each location, weevils were trapped and transported to the laboratory for 15 to 17 days post-treatment to record mortality and mycosis. At both Georgia locations, B. bassiana caused ≥80% mortality and mycosis, which was significantly greater than mortality observed in the check (≤33%); mortality and mycosis in the M. anisopliae treatment at Fort Valley did not differ from that observed in the check. In Texas, due to insufficient replication in plots, statistical comparison among treatments was not possible. However, mean percentages of mortality of pecan weevils after 7 and 14 days were 38 and 55% in the check, 75 and 88% in the B. bassiana-treated plots, and 57 and 75% in the M. anisopliaetreated plots. These results indicate potential for B. bassiana trunk sprays to suppress adult pecan weevil. Future research is needed to determine if the approach contributes to economic levels of crop protection.
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1 June 2009
Efficacy of Entomopathogenic Fungi in Suppressing Pecan Weevil, Curculio caryae (Coleoptera: Curculionidae), in Commercial Pecan Orchards
David I. Shapiro-Ilan,
Ted E. Cottrell,
Wayne A. Gardner,
Robert W. Behle,
Bill Ree,
Marvin K. Harris
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