A laboratory-based method to measure relative pesticide and spray oil efficacy against broad mite, Polyphagotarsonemus latus (Banks)(Acari:Tarsonemidae)

Six pesticides and two spray oils were tested against Polyphagotarsonemus latus. The chemicals were evaluated under laboratory conditions, requiring the development of a novel bioassay method, which is reported here. The pesticide toxicities fell into three distinct groups, namely abamectin, conventional pesticides and oils. The relative pesticide toxicities at the LC(50) level were abamectin 4.9 x 10(-8) g ai l(-1), endosulfan 1.1 x 10(-3) g al l(-1), fenpyroximate 2.3 x 10(-3) g al l(-1), pyridaben 4.1 x 10(-3) g al l(-1), tebufenpyrad 4.4 x 10(-3) g al l(-1), dicofol 4.5 x 10(-3) g ai l(-1), petroleum spray oil 3.4 x 10(-1) g al l(-1) and canola oil 4.1 x 10(-1) g al l(-1). The calculation of the LC(99.9) values allows for resistance monitoring in P. latus and the suggested discriminating concentrations are abamectin 1.0 x 10(-4) g al l(-1); endosulfan, pyridaben and dicofol 1.0 x 10(-1) g ai l(-1) fenpyroximate and tebufenpyrad 5.0 x 10(-1) g ai l(-1).