Effect of fenitrothion on different life stages of black pine bast scale, Matsucoccus thunbergianae

Black pine bast scale, Matsucoccus thunbergianae, is one of the most destructive pests of black pine trees throughout Korea. Toxicities of five commercially available insecticides for scale insects were compared in the laboratory with that of buprofezin 40SC, which is currently used to treat the disease in Korea. Fenitrothion 50EC and buprofezin 40SC significantly suppressed the adult emergence of intermediated male nymphs when exposed to the recommended-field concentrations (RFCs) of 500 and 4,000 ppm, respectively. Fenitrothion 50EC was effective against male pupae even at one-fifth of the RFC, and showed no significant difference from buprofezin 40SC. Fenitrothion 50EC caused significantly higher mortality than buprofezin 40SC towards intermediate female nymphs and eggs, even at half RFC, and on female adults at one-tenth of its RFC. In a field test in a black pine arboretum, 50 ppm of fenitrothion 50EC was equally effective to its RFC (500 ppm) on the settled crawlers. Toxicities of fenitrothion 50EC and buprofezin 40SC to humans, other mammals, and non-target organisms are discussed. Fenitrothion 50EC can be used for urgent control of M. thunbergianae in limited outbreak areas at lower concentrations than its RFC.

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