Prey consumption capacity and functional response of Phytoseiulus persimilis (Acari: Phytoseiidae) feeding on Tetranychus urticae (Acari: Tetranychidae) on different cotton varieties

This study aimed to determine the predatory performance of Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) against Tetranychus urticae Koch (Acari: Tetranychidae) on six different cotton varieties (Gloria, Lima, Carla, DP-396, Edessa, ST-468) with different leaf characteristics. The eggs and the protonymph stages of the prey with six prey densities (5, 10, 20, 40, 80 and 160) were separately offered to a single female predator to determine its predation and oviposition rates for 24h. The results showed that P. persimilis exhibited a Type II functional response to both egg and protonymphal stages of T. urticae irrespective of cotton varieties. The highest attack rates (α) were 0.045 h- and 0.085 h- when the predator fed on eggs and protonymphs of T. urticae on Gloria (low trichome density) variety, respectively. There was a great similarity between the handling times (Th) of P. persimilis feeding on T. urticae eggs and protonymphs among different cotton varieties. No significant difference was found in terms of food consumption of P. persimilis fed on T. urticae eggs in different cotton varieties. In contrast, food consumptions of P. persimilis in all protonymph densities (except 160) were significantly higher on varieties with lower trichome density (Gloria and Lima) compared to the varieties with higher trichome density (Edessa and ST-468). The current study showed that the leaf trichome density of the cotton plant affected the prey consumption capacity of P. persimilis on T. urticae protonymphs. However, more studies are needed to address the issue from a wider perspective, especially to observe the performance and biological control potential of P. persimilis on cotton varieties under field conditions.