Evaluation of Persistence of Selected Miticides Against the Twospotted Spider Mite, Tetranychus urticae

Abstract

Twospotted spider mite, Tetranychus urticae, is a major arthropod pest in greenhouses. Greenhouse producers typically use miticides to control twospotted spider mite (TSM) populations. This study, which involved two replicated experiments, was designed to assess the persistence or longevity and efficacy of translaminar miticides with the active ingredient (a.i.) etoxazole, chlorfenapyr, abamectin, and spiromesifen by applying these miticides to either butterfly bush (Buddleia davidii) or marigold (Tagetes erecta) plants, depending on the experiment, and then artificially infesting the plants with TSM. Based on percent mortality and number of live and dead TSM, several miticides provided adequate control of TSM even after having been applied to the test plants 14 days before being artificially infested with TSM. This suggests that these miticides have extended residual activity. The etoxazole 10 to 12 μm and etoxazole water-dispersible formulations provided control (greater than 85% mortality) of TSM over the course of Expt. 1 with four or less live TSM recovered from treated plants across the three evaluation times (21, 28, and 42 days). Spiromesifen, in Expt. 2, was significantly more effective against both the nymph (89% to 99.2%) and adult (37.3% to 87.9%) stages of the TSM than the other miticides and killed more nymphs (165 to 227) than the other treatments. In general, none of the miticides provided consistent or adequate control of TSM adults across all three evaluation times (49, 56, and 70 days).