اثر نسبت‌های مختلف رهاسازی جداگانه و ترکیبی Phytoseiulus persimilis با Neoseiulus cucumeris یا Amblyseius swirskii در کاهش جمعیت Tetranychus urticae روی گیاه رز در شرایط آزمایشگاهی

The effectiveness of predators in suppressing prey populations is known to be influenced by the predator-prey release ratio. In this study, the separate and combined release of Phytoseiulus persimilis Athias-Henriot with Amblyseius swirskii Athias-Henriot or Neoseiulus cucumeris (Oudemans) was tested for control of Tetranychus urticae Koch in laboratory conditions (25±2°C, 75±5% RH, and 16L:8D h photoperiod). In all experiments, pest and predator(s) were released simultaneously, and evaluations (determining prey density) were conducted after 24 h. The plants without predators were considered as control. Nymphal stages of T. urticae and adult female predators were used for the experiments. One young rose branch with 6-10 leaflets was used that the end of the rose branch was placed in a glass vial (10 ml) full of water. Each young rose branch was enclosed in a plastic container (10×10×18-cm) (L×W×H) and 200×200-µm cloth mesh opening (4 × 4-cm) (L ×W) on the lid. The efficacy of the predators was evaluated at predator:prey ratios of 1:10, 1:20, 1:50, and 1:100 at separate release and 1:1:10, 1:1:20, 1:1:50, and 1:1:100 at combined release. The most suppression of T. urticae occurred in predator:prey ratios of 1:1:10 at the combined release of P. persimilis with A. swirskii or N. cucumerise that decreased 77% and 72% of T. urticae after 24h, respectively. Moreover, the combined release of P. persimilis with both predators, A. swirskii or N. cucumeris did not significantly differ in the reduction of T. urticae population at all release ratios. This study indicated that combined release of P. persimilis with one predator, A. swirskii or N. cucumeris at predator:prey ratios of 1:1:10 would be sufficient to control T. urticae on rose plants which should be tested in long-term studies in greenhouse conditions.