Temperature-Dependent Functional Response of the Predatory Bug Orius laevigatus (Fieber) Preying Upon the Two-Spotted Spider Mite, Tetranychus urticae (Koch)

Temperature is one of the important factors that can influence the predator- prey dynamics. In this research, functional responses of males and females of Orius laevigatus towards Tetranychus urticae nymphs were investigated in laboratory condition at three constant temperatures, 20, 25 and 30°C. Different densities of mixture of protonymph and deutonymph of mite (2, 4, 8, 16, 32 and 64), on cucumber leaf discs (6 cm in diameter), were separately offered to male and female predators. After 24 h, the number of consumed preys was recorded. Ten replicates of the experiment were performed. Logistic regression and nonlinear regression of SAS software were used to determine the type of functional response and estimate the parameters, respectively. Consumption rate of both male and female predators increased with increasing temperature and prey density. Functional responses of both male and female predators to the mite were Type II at 20 and 25°C and Type III at 30°C. At 20 and 25°C, attack rates were estimated to be 0.0452 and 0.0498 h-1for females; and 0.0457 and 0.0460 h-1 for males, respectively. The lowest handling time for both male and female predators was estimated at 25°C. The results revealed that the predatory bug O. laevigatus may be more effective for biological control of T. urticae at higher temperature.