Mite behavior changes due to application of microbial pesticides

Tetranychus urticae (Koch) is a generalist common in greenhouse production. In this environment, mites may come into contact with plants treated with microbial pesticides. Previous research has shown that applications of microbial pesticides can alter host plant volatile composition, resulting in changes in pest mite behavior. We evaluated the application of foliar microbial miticides (Grandevo, Ancora) and soil microbial fungicides (RootShield Plus WP, Stargus) on the behavior of T. urticae on ornamental pepper (Capsicum annuum L. cv. 'Explosive Ember'). Ethovision v. 14 was used to quantify mite preference for plants treated with microbial products. Tetranychus urticae were presented with treated and untreated leaf disks in a choice test. A no-choice test was then performed with leaf disks treated with Ancora and Untreated leaf disks. To determine response to the Ancora product, assays were performed exposing mites to decreasing concentrations of Ancora. An efficacy test was preformed to determine tolerance to direct and residual treatment of Ancora. Our results show there were no differences in plant volatile composition, however, mites with leaf disks treated with Ancora spent more time on the rim of assay arenas compared to other treatments. In the no-choice test, mites spent significantly less time on the Ancora treated leaf disk compared to the Untreated disk. In addition, T. urticae avoided filter paper treated with Ancora, but that avoidance behavior decreased as the concentration of Ancora decreased. These experiments indicate that the application of Ancora acts as a repellent to T. urticae rather than a miticide.