Residual Activity of Acaricides for Controlling Spider Mites in Watermelon and Their Impacts on Resident Predatory Mites

Abstract Twospotted spider mite, Tetranychus urticae Koch (Trombidiformes: Tetranychidae), is an important, worldwide pest of watermelon, Citrullus lanatus L. (Thunb.) Matsum. & Nakai (Cucurbitales: Cucurbitaceae). Feeding results in chlorotic spots and leaf necrosis, which can substantially reduce yields. In T. managed solely with acaricides. Issues acaricide resistance pesticide label restrictions on number applications per season require research-based recommendations products effective, long-lasting residues. To improve for management watermelon to measure possible effects non-target beneficial mites, we conducted efficacy trials two locations South Carolina, United States. The adulticidal abamectin, bifenazate, fenpyroximate, tolfenpyrad the ovicidal spiromesifen etoxazole were tested. We also bioassays better determine duration field trials, all acaricides except reduced abundance, but abundance most common predatory Neoseiulus fallacis (Garman) (Mesostigmata: Phytoseiidae). bioassays, abamectin bifenazate residues caused high adult mortality at up 21 d after treatment, performing than fenpyroximate tolfenpyrad. Etoxazole longer lasting, <1 offspring treated female treatment 28 treatment. Based efficacy, or should be rotated fast knockdown active stages while reducing reproduction, respectively. However, development registration more selective needed preserve biological control by mites.