Effects of pyrifluquinazon spray on the population densities of predacious natural enemy, Orius spp., and kanzawa spider mite, Tetranychus kanzawai, in eggplant fields
2016
Hoshino, S.
To determine whether pyrifluquinazon can be utilized as selective insecticide to plant bugs in Miridae in eggplant fields, numbers of predacious natural enemy, Orius spp., and Kanzawa spider mite, Tetranychus kanzawai were compared among eggplant fields sprayed with pyrifluquinazon, permethrin or control. Numbers of Orius spp. per leaf decreased drastically in fields sprayed with permethrin. No Orius spp. were recorded on leaves 3 days after spraying. Their numbers were suppressed during 8 and 14 days after spraying and became as same as control 20 days after spraying. On the contrary, decline of Orius spp. in fields sprayed with pyrifluquinazon was temporally. Tetranychus kanzawai seemed to be primary prey of Orius spp. in the fields. Because of the rapid decline of predacious natural enemy, Orius spp., densities of T. kanzawai increased rapidly in the fields sprayed with permethrin, resurgence of T. kanzawai, while such increase were not recognized in the fields sprayed with pyrifluquinazon. It is preferable to select insecticides with no ill effects on predacious natural enemies like Orius spp. in eggplant fields. Additionally, selection of insecticides with no deleterious effects on biological community including their prey in and near eggplant fields would be ideal.
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