A new predatory gall midge with potential to control tarsonemid and eriophyoid mites

Abstract: Minuscule phytophagous mites of the Eriophyidae and Tarsonemidae families are
increasingly causing serious crop damage in various ornamental crops in The Netherlands. The tarsonemid mites Tarsonemus violae Schaarschmidt and the broad mite Polyphagotarsonemus latus (Banks) cause serious damage in gerbera and the Dutch tulip production suffers from infestations by the eriophyoid dry bulb mite Aceria tulipae Keifer in the post- harvest phase of tulip bulbs. The increasing problem with these tiny mites that hide deep into plant parts is related to the reduced use of broad-spectrum pesticides. Biological control by commercial phytoseiid predatory mites provides reasonable control of tarsonemid mites in gerbera, but is not successful in the control of dry bulb mites during the storage of tulip bulbs. In our search for new species of indigenous natural enemies, we found several potential candidates on organic flower bulbs. Here we present one of the candidates, the small predatory gall midge Trisopsis tyroglyphi (Banks) (Diptera: Cecidomyiidae), which was recorded for the first time in The Netherlands. Gall midges are a large group of insects that can cause very characteristic galls in plants, but some of these gall midges have a different lifestyle and feed on fungi or insects and mites. In the latter case, they are considered beneficial and can be used for biological control. After setting up a mass culture, we investigated the development time of T. tyroglyphi at different temperatures and tested it as a potential biological control agent of the broad mite in gerbera and dry bulb mite on garlic.