Olfactory responses of the predatory mite Phytoseiulus persimilis (Acari: Phytoseiidae) to rose leaves: starvation and previous host plant experience

The effect of host plant experience and different hunger periods on the olfactory response of Phytoseiulus persimilis was studied on rose leaves under laboratory conditions. When clean air was considered as the olfactometer fixed arm, P. persimilis showed a significant preference towards odours related to the alternative arms i.e. clean leaves, T. urticae-infested leaves, leaves occupied by Frankliniella occidentalis and leaves occupied by conspecifics regardless of starvation time and experience. When we replaced clean air by clean rose leaves, the naïve predators with 10 hours starvation and the experienced ones with both 5 and 10 hours starvation showed a significant preference (towards T. urticae-infested leaves) rather than clean leaves. When the predators were offered clean leaves vs. leaves occupied by thrips, neither naïve nor experienced P. persimilis with 5 hours starvation made a significant preference between the arms, while the ones kept starved for 10 hours preferred clean air regardless of experience. Receiving odours related to conspecifics vs. clean rose, the naïve P. persimilis females with 5 hours starvation and the naïve and experience ones kept starved for 10 hours avoided odours related to conspecifics. The five hour-starved experienced predators and the 10 hour-starved naïve and experienced ones moved towards T. urticae-infested leaves when the alternative arm was consisted of leaves occupied by thrips. Receiving odours related to T. urticae-infested leaves from one arm and odours related to leaves occupied by conspecifics, most of the predators moved towards the former arm regardless of experience and starvation time. When the predators were offered T. urticae-infested leaves vs. leaves occupied by thrips, a significant movement towards spider mites was observed both in experienced and naive treatments kept starved for 10 hours and in five hour-starved experienced ones. Irrespective of the starvation time, the predatory mite’s previous experience did not have a significant effect on the time needed by P. persimilis to pass the lateral arms of the olfactometer. Both experience and starvation affected the predator’s oviposition rate.