Pyridaben baseline assays for adult female european red mite (Acari: Tetranychidae) and eggs

摘要

Bioassays of Panonychus ulmi (Koch) (Acari: Tetranychidae) with the miticide/insecticide pyridaben indicate this product is toxic to both eggs and motile stages. For contact ovicidal tests, adult female P. ulmi were allowed to lay eggs on untreated peach leaf disks. Mites were removed at 18 h then the leaf disks with eggs were dipped for 5 s in serial dilutions of pyridaben or water as a control. Treated leaf disks with eggs were then placed on wet cotton and held in a growth chamber to allow eggs to hatch. For residual ovicidal assays, adult female P. ulmi were allowed to oviposit either on water-treated peach leaf disks or leaf disks treated with serial dilutions of pyridaben for 18 h before removal of the mites. Adult mortality was assessed when the mites were removed from the residual ovicidal assays. Concentration-response line parameters for treated eggs from the contact ovicide assays were: LG_50s (2.4-3.3 ppm), LC_90s (7.2-8.7 ppm), slopes (2.3-2.9). Line parameters from the residual ovicidal assay were: LC_50 (32 ppm), LC_90 (130 ppm), slope (2.1). Adult female P. ulmi placed on treated surfaces were more sensitive to pyridaben than eggs. Concentration-response line parameters for the residual adult P. ulmi assays were: LC_50s (1.1-1.5 ppm), LC_90s (2.6-3.9 ppm), slopes (2.8-3.3). Because pyridaben is toxic to several lifestages of P. ulmi, use patterns should be part of an overall miticide resistance management program.