Journal of Pest Science, May 25, 2018
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Abstract: T. Saito and M. Brownbridge. Foliage-dwelling predatory mites and foliar applications of mycoinsecticides are commonly used in biological control programs for Western ﬂower thrips. A laboratory study was designed to examine the compatibility of two foliage-dwelling predatory mites with two commercially available mycoinsecticides, followed by a greenhouse study to assess their combined eﬃcacy against Western ﬂower thrips, with a view to their concurrent use in an integrated strategy. The following commercially available biocontrol agents were evaluated: the predatory mites, Neoseiulus cucumeris (Oudemans) and Amblyseius swirskii (Athias-Henriot); and entomopathogenic fungi, Metarhizium anisopliae (Metschnikoﬀ) Sorokin (now classiﬁed as Metarhizium brunneum) strain F52 and Beauveria bassiana (Balsamo) GHA strain. Mortality caused by the mycoinsecticides ranged from 0 to 15.98% in the laboratory studies. In the greenhouse, the relative eﬃcacy of predatory mite slow-release breeding sachets, Met52 EC spray, and a combined application was determined. Under high pest pressure, Met52 EC-alone was not as eﬀective as N. cucumeris-alone or the combination treatment over 8weeks. Neoseiulus cucumeris-alone provided better control of thrips than Met52 EC, but in a mixed infestation of thrips and two-spotted spider mites, the combination
treatment worked best overall; the spider mites were eﬀectively suppressed by Met52 EC. Under low pest pressure in the experiment with A. swirskii, use of Met52 EC or A. swirskii sachets eﬀectively suppressed thrips population growth; moreover, the combination treatment completely eliminated both thrips and spider mites.