Assessing a new predatory phytoseiid mite to North America, Transeius montdorensis

The western flower thrips, Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), continues represent a problematic and cosmopolitan pest for greenhouse and field crops. In response, predatory phytoseiid mites have an excellent potential to suppress thrips populations, though their success can depend on what species is employed and in what environment. This study aimed to compare how well commercially available predatory mite species serve in thrips suppression under short-day and cool-temperature conditions common to greenhouse environments in winter and early spring in the Northern hemisphere. Importantly, this study also assessed a new-to-North-America phytoseiid, Transeius montdorensis Schicha (Acari: Phytoseiidae). To begin, laboratory trials were conducted which compared rates of thrips predation and oviposition by T. montdorensis under simulated summer or winter conditions. This predator consumed similar numbers of 1st instar thrips, and laid similar numbers of eggs under either of these conditions. Next, short-season greenhouse cage trials were conducted to evaluate crop establishment and thrips suppression by this and other phytoseiid mite species including Amblyseius swirskii, Amblydromalus limonicus and Neoseiulus cucumeris. In two, 4-5 week long trials, we found that the number of predatory mites on pepper plants was greatest for T. montdorensis containing cages. In this treatment, high levels of thrips suppression were observed, either equal to those achieved by A. swirskii or A. limonicus treatments or superior to those observed in N. cucumeris treatment cages. These findings highlight the potential value of applying T. montdorensis for year-round thrips management in North America.