The search for a new beneficial to control the tomato russet mite, Aculops lycopersici: From the very beginning to a commercial product

Abstract: The tomato russet mite (TRM), Aculops lycopersici, is an important pest in
greenhouse tomato worldwide. Actually, TRM control relies on the use of sulphur and chemical acaricides with important negative effects on the biological control systems. A durable IPM strategy needs, therefore, an efficient biological control agent. Since extensive research had shown that Phytoseiids do not establish on tomatoes, hampered by glandular trichomes, we started a survey for smaller natural enemies on wild plants from 2017 until 2019. We focused thereby on hairy plants such as Rubus spp. or solanaceous plants in Belgium and neighboring countries (projects Ducato and Balto). More than 200 samples were screened, predatory mites identified by slide mounting and selected small rearings were set up. Apart from Thriophtydeids and Phytoseiids, the Iolinids, Homeopronematus anconai and to a lesser extent, Pronematus ubiquitus were frequently recovered. Since literature showed that both Iolinids had a potential to control Eriophyids, lab tests were conducted. Both were able to reproduce on TRM and, positive for mass rearing, on cattail pollen, whenever they can feed on plant tissue. P. ubiquitus had a higher predation rate on TRM and a faster life cycle on both pollen and TRM when compared to H. anconai. Therefore, we continued semi-field and field trials with P. ubiquitus. The potential of P. ubiquitus to control TRM was confirmed when installed preventive on the tomato crop. Further research is planned to unravel the best way to install and maintain P. ubiquitus on a commercial crop.