Factors affecting the resident time of the predatory mite Phytoseiulus persimilis (Acari : Phytoseiidae) in a prey patch

We studied the effect of Tetranychus urticae-infested plant volatiles on th e resident time of the predatory mite Phytoseiulus persimilis on a kidney b ean leaf disc with T. urticae eggs. The leaf was set in a wind tunnel into which either T. urticae-infested or -uninfested leaf volatiles were introdu ced. With both volatile flows, the predators showed longer resident time in discs with prey eggs than in those without eggs. At the same egg density l evels per disc, the predators stayed longer in uninfested-leaf volatile flo w than in infested-leaf volatile flow. Chemical analysis showed that the in fested leaves produced seven terpenoids [(3E)-4,8-dimethyl-1,3,7-nonatriene , (3E,7E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, alpha-caryophyllene, b eta-caryophyllene, alpha-germacrene-D and alpha-farnesene] and methyl salic ylate. The results suggest that the predators utilize both the prey density level in a patch they currently inhabit and T. urticae-infested volatiles from outside the patch for determining whether to remain in or leave the pa tch.