Olfactory responses of Phytoseiulus persimilis to rose plants with or without prey or competitors

Abstract

Predators of herbivores use plant volatiles to find patches with prey. Plants benefit from this attraction as predators will reduce herbivore damage. Plants also benefit from arresting predators before prey arrival, as this will minimize future herbivore damage. For predators, however, the benefits of being attracted to clean plants depends on alternative food and on the degree of competition on other plants. Although the interactions between the predatory mite Phytoseiulus persimilis and its plant host are well-studied on cucumber or bean, that with other plants remain largely unknown. Here, we studied the olfactory response of P. persimilis to volatiles of rose plants that were either clean (i.e., empty), occupied by their prey (Tetranychus urticae) or by conspecific competitors, using bean and cucumber as comparisons. We found that, relative to clean air, predators were attracted to clean plants, and also to plants with prey. On cucumber and bean, naïve predators preferred plants with prey over clean plants, but no such discrimination occurred on rose plants. However, after 24 hours of experience with rose plants infested with T. urticae, predators preferred those plants to clean roses. Predators avoided plants with prey and conspecifics, even without any previous experience. Our results show that predator attraction to plants hinges on the plant species and on experience. Attracting predators to clean plants may favour biological control, as plants may become better guarded from herbivores, but it may also be detrimental, as predators may starve on those plants. © Maleknia B. et al.