Functional Response of Predatory Bug, Orius albidipennis (Reuter) to Melon Aphid, Aphis gossypii (Glover) and Two Spotted Spider Mite, Tetranychus urticae Koch

The functional response is an essential factor in selecting natural enemies for biological control programs. Orius albidipennis (Reuter), the abundant anthocorid species is an important predator of immature stages of thrips, aphids, whiteflies and spider mites. In this research, type and parameters of functional response of this predator were assessed against two prey species, Tetranychus urticae Koch and Aphis gossypii Glover. Different prey densities of 5, 10, 20, 30, 40 and 50 two day old nymphs were presented as prey and the experiments replicated 10 times. After 24 h, the numbers of survived preys were counted. The results of logistic regression indicated that the O. albidipennis exhibited type III functional response to both preys. Values of b constant that relates attack rate to initial prey density (a=bN0) using Roger's model for T. urticae and A. gossypii nymphs were 0.0065±0.00096 and 0.0046±0.0004 h-1, respectively, which were differed significantly. Additionally, handling time for T. urticae and A. gossypii were estimated to be 0.646±0.029 and 0.625±0.022 h, respectively. Our study, as a part of evaluation of O. albidipennis as a biocontrol agent, suggests that this predator has good potential for using against two spotted spider mite and cotton aphid.