Megalurothrips usitatus (Bagnall) (Thysanoptera: Thripidae), a major pest of leguminous crops in the Asian tropics, was first reported in Florida in 2020 and has since spread across Central America and the Caribbean. To control M. usitatus, Florida snap bean growers face higher production costs from increased insecticide use. To achieve more effective and sustainable management of M. usitatus, integrated approaches, including biological control, are needed. This study evaluated 2 commercial predatory mites, Amblyseius swirskii (Athias-Henriot) and Neoseiulus cucumeris (Oudemans) (Mesostigmata: Phytoseiidae), as biological control agents against M. usitatus through leaf disk bioassays and growth room cage studies. In the leaf disk bioassays, both predators showed high survival while feeding on M. usitatus, with daily oviposition rates of 1.07 for A. swirskii and 1.48 for N. cucumeris, and consumed 3 to 4 first instar larvae per day. Growth room cage studies evaluated whether these predatory mites could suppress M. usitatus on Phaseolus vulgaris plants. Weekly evaluations over 4 wk showed that A. swirskii significantly reduced M. usitatus population by approximately 75% by week 4. However, mean thrips densities remained high, with 101.2 ± 31.2 individuals per plant (mean ± SE), and significant plant damage was observed. Neoseiulus cucumeris did not significantly reduce thrips populations compared to control plants. This study provides evidence that A. swirskii can reduce M. usitatus populations on P. vulgaris plants under these conditions, but suppression remained limited, indicating that further work is needed to improve effectiveness.
Barros et al. (Tue,) studied this question.