Foraging behavior of Galendromus flumenis on Banks grass mite, Oligonychus pratensis

The Banks grass mite, Oligonychus pratensis (Banks) (Tetranychidae) is a spider mite with wide distribution throughout the United States, which can cause serious yield reductions in date production. The mites feed on unripe green fruits resulting in bronzing scars and cracked skin. This study was conducted to evaluate the potential efficiency of Galendromus flumenis (Chant) (Phytoseiidae) as a biological control agent for Banks grass mite suppression. For this purpose, prey stage preference at constant densities of eggs, larvae, protonymphs and deutonymphs of prey, and functional response of female G. flumenis to different prey densities were investigated on corn leaf arenas under laboratory conditions of 30±0.5 °C, 50±10% RH and 16L: 8D photoperiod. Our experimental results indicated that the predatory mite consumed significantly more eggs than other prey stages. Functional response type of the predator also was determined using a logistic regression model. The predatory mite exhibited a Type II response on all immature prey stages. Functional response parameters of G. flumenis and the suitability of this predator for biological control of O. pratensis will be discussed.