Biological control of twospotted spider mites [Tetranychus urticae Koch (Acari: Tetranychidae)] using Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseidae) at different ratios of release on field-grown tomatos

In the present study, the effectiveness and optimum release times of the phytoseiid mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseidae) at release ratios of 1:10, 1:20 and 1:40 predator:prey were evaluated to reveal its potential for biological control of twospotted spider mites [Tetranychus urticae Koch (Acari: Tetranychidae)] on tomato field in the canakkale province of Northwest Turkey. After release of the predators and prey in the second crop production period, counting was carried out by sampling of tomato leaves for a period of 8 weeks. P. persimilis released at ratios of 1:10 and 1:20 predator:prey significantly suppressed T. urticae and remained on the tomoto leaves during sampling. At release ratios 1:10 and 1:20 predator:prey, T. urticae populations on tomato reached 76.0 +/- 17.9 and 39.4 +/- 7.3 per leaf, repectively, and decreased by half after 8 weeks. Our results indicate that P. persimilis can be released for the effective control of mites from the mid-August to the beginning of September on tomato in the study region. Also, it is concluded that the release of P. persimilis on tomato grown as the second crop will have a higher potential for biological control of T. urticae.