Phytoseiid mites prey effectively on thrips eggs: Evidence from predation trials and molecular analyses

Abstract

It is generally assumed that predation by phytoseiid mites (Acarina: Phytoseiidae) on thrips is mainly limited to the first and, to a lesser extent, the second thrips instars. Thrips eggs are imbedded in plant tissue and are supposed to be out of reach of most predators. Using a dual approach combining feeding trials with molecular gut content analysis, we confirmed that eggs of the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), can be vulnerable to attack by a subset of phytoseiid species. Of the five species investigated, the generalist predators Amblyseius largoensis and Amblyseius swirskii were shown to most readily feed on thrips eggs, followed by Neoseiulus californicus, which is classified as a selective predator of tetranychid mites. Neoseiulus longispinosus and Proprioseiopsis lenis did not or very rarely consume thrips eggs. As substantial reductions of hatching (up to 30%) were observed, predation on eggs should not be ignored when assessing the efficacy of phytoseiids as biological control agents against thrips.