Production of herbivore-induced plant volatiles and their attractiveness to Phytoseius persimilis (Acari : Phytoseiidae) with changes of Tetranychus urticae (Acari : Tetranychidae) density on a plant

Using GC-MS, we studied the time course of Tetranychus urticae-induced kidn ey bean plant volatile production during the period from foundation to coll apse of the T. urticae colony. The density of T. urticae females showed a u nimodal curve, which was followed by the production of T. urticae-induced p lant volatiles. The intensity of the olfactory response of the predatory mi te Phytoseiulus persimilis to the induced volatiles in a Y-tube olfactomete r correlated with the amount of volatiles per plant. In the period before t he increase of the second generation of female T. urticae, the infested pla nt did not attract predatory mites. Such a period can be considered to cons titute a temporary enemy-free period for T. urticae.