Abstract
The study of functional response characteristics of natural enemies is one of the most important approaches to assess their efficiency in regulating the pest population as they are key aspects in the dynamics of predator-prey interactions. In the present study, the functional response type and parameters, and maximum feeding capacity of the predatory mite Cydnoseius negevi Swirski & Amitai) Acari: Phytoseiidae) deutonymph and adult female were assessed at different densities of movable stages of the date palm mite DPM) Oligonychus afrasiaticus McGregor) and two-spotted spider mite TSSM) Tetranychus urticae Koch Acari: Tetranychidae). The experiments were carried out at 30 +/- 2 degrees C and relatively low humidity of 35 +/- 5 % RH under controlled conditions, for the first time. The logistic regression model was used to determine the type of functional response exhibited by C. negevi. Both the stages of predator showed Type II functional response when fed the DPM and TSSM individuals at different stages. Roger's random-predator equation was used to define the handling time Th) and attack rate a) coefficients of type II functional response by fitting the equation into the non-linear least square regression model. The longest Th was shown by deutonymph and adult females of C. negevi when they fed on the DPM and TSSM females, and TSSM females, respectively. Furthermore, no significant differences were recorded for most of the a values of the deutonymph and adult female of C. negevi among different stages of DPM and TSSM. The maximum feeding capacity of C. negevi adult female was significantly higher for DPM female when compared with that of TSSM. According to previous and current studies, C. negevi could be a potential predator at a wide range of humidity.