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[EN] In mite communities, behavioral and foraging decisions of individuals rely on semiochemicals that they gather from the environment, which contain odors from plants, herbivores, and predators. Because herbivorous mites commonly co-occur with several species of phytoseiid predatory mites, which may engage in intraguild predation (IGP), predator mite decision-making relies on their ability to recognize odors signaling the presence of the herbivore but also that of potential competitors/predators. Here the odor-related foraging decisions of three predatory mites, Euseius stipulatus (Athias-Henriot), Neoseiulus californicus (McGregor) and Phytoseiulus persimilis (Athias-Henriot) (Mesostigmata: Phytoseiidae), which co-occur in citrus, compete for the herbivore Tetranychus urticae Koch (Prostigmata: Tetranychidae), and can engage in IGP were investigated. The composition of the volatile blends associated with the three predators was characterized. Moreover, the effect of these odors on the predators foraging decisions was measured. Results revealed that (1) the volatile signature of the three predatory mites is species specific, (2) the predators¿ foraging behavior is affected by heterospecific predator odors, and (3) predator responses strongly depend on the host plant: mutual attraction and mutual repellence occurred in Cleopatra mandarin and sour orange, respectively. These findings have important consequences for the management of systems where these species occur. The odor blends that make predators that share pest species as prey avoid each other could be used to improve pest control by minimizing undesired negative interactions among predator species, and by locally increasing predation risk on herbivore pest species.

[EN] In mite communities, behavioral and foraging decisions of individuals rely on semiochemicals that they gather from the environment, which contain odors from plants, herbivores, and predators. Because herbivorous mites commonly co-occur with several species of phytoseiid predatory mites, which may engage in intraguild predation (IGP), predator mite decision-making relies on their ability to recognize odors signaling the presence of the herbivore but also that of potential competitors/predators. Here the odor-related foraging decisions of three predatory mites, Euseius stipulatus (Athias-Henriot), Neoseiulus californicus (McGregor) and Phytoseiulus persimilis (Athias-Henriot) (Mesostigmata: Phytoseiidae), which co-occur in citrus, compete for the herbivore Tetranychus urticae Koch (Prostigmata: Tetranychidae), and can engage in IGP were investigated. The composition of the volatile blends associated with the three predators was characterized. Moreover, the effect of these odors on the predators foraging decisions was measured. Results revealed that (1) the volatile signature of the three predatory mites is species specific, (2) the predators¿ foraging behavior is affected by heterospecific predator odors, and (3) predator responses strongly depend on the host plant: mutual attraction and mutual repellence occurred in Cleopatra mandarin and sour orange, respectively. These findings have important consequences for the management of systems where these species occur. The odor blends that make predators that share pest species as prey avoid each other could be used to improve pest control by minimizing undesired negative interactions among predator species, and by locally increasing predation risk on herbivore pest species.

[EN] Sour orange, Citrus aurantium, displays higher constitutive and earlier inducible direct defenses against the two-spotted spider mite, Tetranychus urticae, than Cleopatra mandarin, Citrus reshni. Moreover, herbivore-induced plant volatiles (HIPVs) produced by sour orange upon infestation can induce resistance in Cleopatra mandarin but not vice versa. Because the role of these HIPVs in indirect resistance remains ignored, we have carried out a series of behavioral assays with three predatory mites with different levels of specialization on this herbivore, from strict entomophagy to omnivory. We have further characterized the volatile blend associated with T. urticae, which interestingly includes the HIPV methyl salicylate, as well as that produced by induced Cleopatra mandarin plants. Although a preference for less defended plants with presumably higher prey densities (i.e., C. reshni) was expected, this was not always the case. Because predators' responses changed with diet width, with omnivore predators responding to both HIPVs and prey-related odors and specialized ones mostly to prey, our results reveal that these responses depend on plant genotype, prey presence and predator diet specialization. As the different volatile blends produced by infested sour orange, induced Cleopatra mandarin and T. urticae itself are attractive to T. urticae natural enemies but not to the herbivore, they may provide clues to develop new more sustainable tools to manipulate these agriculturally relevant species.

[EN] Sour orange, Citrus aurantium, displays higher constitutive and earlier inducible direct defenses against the two-spotted spider mite, Tetranychus urticae, than Cleopatra mandarin, Citrus reshni. Moreover, herbivore-induced plant volatiles (HIPVs) produced by sour orange upon infestation can induce resistance in Cleopatra mandarin but not vice versa. Because the role of these HIPVs in indirect resistance remains ignored, we have carried out a series of behavioral assays with three predatory mites with different levels of specialization on this herbivore, from strict entomophagy to omnivory. We have further characterized the volatile blend associated with T. urticae, which interestingly includes the HIPV methyl salicylate, as well as that produced by induced Cleopatra mandarin plants. Although a preference for less defended plants with presumably higher prey densities (i.e., C. reshni) was expected, this was not always the case. Because predators' responses changed with diet width, with omnivore predators responding to both HIPVs and prey-related odors and specialized ones mostly to prey, our results reveal that these responses depend on plant genotype, prey presence and predator diet specialization. As the different volatile blends produced by infested sour orange, induced Cleopatra mandarin and T. urticae itself are attractive to T. urticae natural enemies but not to the herbivore, they may provide clues to develop new more sustainable tools to manipulate these agriculturally relevant species.