Introduction of Typhlodromus (Anthoseius) recki in protected tomato crop with banker plants to control Aculops lycopersici

Abstract: The management of A. lycopersici, the Tomato Russet Mite (TRM), mainly relies on
pesticides although they have shown partial efficacy and negative side effects. A European
endemic Phytoseiidae: Typhlodromus (Anthoseius) recki has shown good predatory ability on TRM in lab experiments. Because no mass-rearing was available, we used banker plants to
introduce this biocontrol agent. We selected Mentha suaveolens (mint) and Phlomis fruticosa (Jerusalem sage, here sage) on which it naturally occurred. Two trials were conducted in greenhouse to evaluate whether (i) T. (A.) recki achieved the control of TRM and whether (ii) mint and sage were suitable for installing T. (A.) recki on tomato. In the first trial, we introduced one branch of mint or sage pre-inoculated with 30 or 60 T. (A.) recki per tomato plant, infested with TRM. The length of tomato stem russeting was shorter within parcels with the predator compared to the chemical and untreated controls, regardless the banker plant species and the predator density. In the second trial, we introduced 2 potted banker plants inoculated with 30 T. (A.) recki per pot at an extremity of a row of 20 tomato plants infested with TRM. Sixty days later, we found T. (A.) recki on tomato until 4.5 m from both banker plants with a slightly decreasing population with distance from banker plants. Final populations of predator were low and significantly higher in tomato rows with mint (0.43/leaflet) than with sage (0.15/leaflet). Our results confirm the interest of banker plants to introduce T. (A.) recki and its ability to control TRM. Further field trials are needed to optimize feasibility, efficacy, and costs of this biocontrol strategy.