BIOLOGICAL CONTROL Response of the Predatory Mite Phytoseiulus macropilis (Banks) to Volatiles Produced by Strawberry Plants in Response to Attack by

ABSTRACT- The attack of phytophagous mites may induce plants to produce volatiles, which in turn may attract predators. The occurrence of multiple phytophagous infestations on plants may infl uence predator response. In this paper, we investigated whether the attraction of the predatory mite Phytoseiulus macropilis (Banks) to phytophagous-infested plants would change with the simultaneous presence of two tetranichid mites Oligonychus ilicis (McGregor) and Tetranychus urticae Koch. While the former species is rarely found on strawberry plants and is only occasionally found in association with P. macropilis, the latter is commonly found on strawberry plants and is frequently found in association with P. macropilis. Y-tube olfactometer test assays demonstrated that the predator preferred plants infested with T. urticae, avoided plants infested with O. ilicis, and had no preference for plants infested with both phytophagous mite species. These results indicated that the presence of a non-prey species (O. ilicis) on a given plant can alter the response of the predator to one of its prey (T. urticae). The consequences of the predatory behavior determined in this study on the predator ability to control T. urticae population on strawberry plants are discussed. KEY WORDS: Induced defense, Fragaria, Tetranychus urticae, Oligonychus ilicis The attack of phytophagous mites to plants may induc