Submitted to: Phytoparasitica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2020
Publication Date: 4/1/2020
Citation: Yee, W.L. 2020. Laboratory evaluation of CX-10282 containing Beauveria bassiana (Hypocreales: Clavicipitaceae) strain GHA against adult Rhagoletis indifferens (Diptera: Tephritidae). Phytoparasitica. 48(2):231-245. https://doi.org/10.1007/s12600-020-00797-5.
Interpretive Summary: Western cherry fruit fly is a quarantine pest that attacks cherries in western North America. Spinosad, pyrethrin, and neem oil are products approved for use against the fly in organic cherry production, but efficacy of pyrethrins and neem is low and spinosad might cause side effects on some beneficial parasitoids. Personnel at the USDA-ARS Temperate Tree Fruit & Vegetable Research Unit in Wapato, WA conducted laboratory studies on the effects of the commercial product CX-10282 containing the fungal pathogen Beauveria bassiana on adult fly mortality. Results showed that CX-10282 can cause 100% fly mortality. This is important because it suggests CX-10282 has the potential to be another organic control agent of adult flies.
Technical Abstract: Western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is a pest of cherries (Prunus spp.) in western North America that potentially could be managed using the fungus Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Clavicipitaceae). Here, the product CX-10282 containing 11.3% B. bassiana strain GHA was evaluated as a potential control agent for adult R. indifferens by determining whether it can cause 100% fly mortality in the laboratory. Low or high label rates of 5.4 x 107 or 1.7 x 108 conidia/ml in different modes of application and application volumes were tested. Fly mortality using all treatment methods 14-25 d post exposure was 70.4-100%. Topical application appeared most effective for killing flies. When a 1 or 2 µl drop of CX-10282 containing 5.3 x 104 to 3.3 x 105 conidia was applied onto a single female fly, 100% mortality was reached by 3-6 d. A 2, but not 1 µl drop of high rate CX-10282 often killed flies by smothering them, likely due to narrow range oils in CX-10282. When CX-10282 was sprayed into a container with flies to produce 1.6 x 105 or 4.8 x 105 conidia/cm2, 100% mortality was reached by 12 d. When a 9-cm diam filter paper with 2.8 x 107 conidia/cm2 was exposed to flies inside a container, 100% mortality was reached by 9 d. Dead treatment flies had mycoses rates of 68.8-93.0%. Taken together, findings suggest that field studies to evaluate CX-10282 as an organic control agent of adult R. indifferens are worth pursuing.