Efficacy of single and combined release of Phytoseiulus persimilis and Amblyseius swirskii at different release ratios for control of Tetranychus urticae and Frankliniella occidentalis on rose plants

Abstract

Single and combined release of Phytoseiulus persimilis Athias-Henriot and Amblyseius swirskii Athias-Henriot was tested for control of Tetranychus urticae Koch and Frankliniella occidentalis (Pergand) on rose plants. The efficacy of the predators was evaluated at predator:prey ratios of 1:2, 1:5, 1:10, 1:20, 1:50 and 1:100 in laboratory experiments, and release rates of 20, 40 and 100 predators per m2 in microcosm experiments. In all treatments, release of predator(s) significantly decreased T. urticae population and larval population of F. occidentalis compared to the control treatment. In laboratory experiment, the most suppression of T. urticae occurred in predator:prey ratios of 1:2 and 1:5 that decreased 95% and 93.5% of T. urticae after 24 h, respectively. In microcosm experiments, release rates of 100 and 40 P. persimilis per m2 eradicated (100%) the T. urticae population at 30 days after releasing the predator. Based on our findings, P. persimilis and A. swirskii can be released simultaneously at the rates of 20 and 100 individuals per m2, respectively for successful control of T. urticae and F. occidentalis on rose plants.