Functional and Numerical Responses of Phytoseiulus persimilis to Tetranychus urticae Density on Cucumber

Abstract

Functional and numerical responses of the predatory mite Phytoseiulus persimilis to varying prey densities of Tetranychus urticae were investigated on cucumber plants under controlled laboratory conditions to evaluate predator–prey interaction dynamics and biological control efficiency. Experiments were conducted across a gradient of prey densities, and predator feeding rates, attack efficiency, and reproduction were recorded over defined observation periods. Results demonstrated a typical density-dependent functional response, with predation rates increasing at low to moderate prey densities and reaching a saturation point at higher densities due to handling time constraints. Numerical response analysis revealed a positive relationship between prey density and predator reproduction, with increased oviposition and population growth observed at higher prey availability. The type II functional response model best described the predation pattern, indicating rapid initial prey consumption followed by deceleration as prey handling time limited further feeding. Increased prey density also enhanced predator activity and aggregation on infested leaf surfaces, improving overall suppression efficiency of spider mite populations. However, at very high prey densities, prey escape and spatial interference among predators slightly reduced per capita consumption rates. The study confirms the high potential of P. persimilis as an effective biological control agent against T. urticae in cucumber cultivation systems. These findings support the integration of predator release strategies based on pest density thresholds for optimized management of two-spotted spider mite infestations in protected and open-field cucumber production.