Laboratory measurement of the functional and numerical responses of the predaceous mite, Typhlodromus (T.) setubali to Panonychus ulmi (Phytoseiidae: Tetranychidae)

Background The functional response of a predator is one of the fundamental methods in ecological studies. Typhlodromus (T.) setubali (Dosse) is an indigenous predaceous mite recently re-described in Morocco. It was reported on various crops around the Mediterranean basin. This study aims to assess the functional response of T. (T.) setubali to the densities of 2, 4, 8, 16, 32, 64, and 128 immature stages of Panonychus ulmi under the controlled conditions of 26 ± 1 °C, 65 ± 5 % RH and 16:8 h L: D photoperiod. The logistic regression was used to determine the functional response and the oviposition activity of predator females was followed to evaluate the numerical response. Thereafter, both parameters (the attack rate (α) and handling time (Th)) were estimated and the results were entirely discussed. Results Logistic regression analysis revealed a Holling type II functional response, indicating that the number of P. ulmi killed by T. (T.) setubali females increased as the prey density increased. The values of attack rate (α) and handling time (Th) were 0.029 prey/ day and 0.573 prey, respectively. The oviposition of females increased above the prey density of 6.54 mites/cm2 and the highest value (m) was 1.86 eggs/ day. Finally, the prey density needed to achieve half the maximum response (n) was estimated to be 2.15 prey.Conclusions The functional response analysis is one of the most rigorous methods for understanding the ecophysiology of a predator. The proportions of prey consumed by T. (T.) setubali were higher at lower densities for P. ulmi immatures, implying that T. (T.) setubali should be more effective at suppressing the red spider mite populations at lower densities. Further laboratory-based studies are needed to draw biological conclusions.