A laboratory-based method to measure relative pesticide and spray oil efficacy against broad mite, Polyphagotarsonemus lotus (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 LC₅₀ level wereabamectin 4.9 × 10^-8 g ai 1^-1, endosulfan 1.1 × 10^-3 g ai 1^-1, fenpyroximate 2.3 × 10^-3 g ai 1^-1, pyridaben 4.1 × 10^-3 g ai 1^-1, tebufenpyrad 4.4 × 10^-3 g ai 1^-1, dicofol 4.5 × 10^-3 g ai 1^-1, petroleum spray oil 3.4 × 10^-1 g ai 1^-1 and canola oil 4.1 × 10^-1 g ai 1^-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 × 10^-4 g ai 1^-1; endosulfan, pyridaben and dicofol 1.0 × 10^-1 g ai 1^-1 fenpyroximate and tebufenpyrad 5.0 × 10^-1 g ai 1^-1.