Plant-phytoseiid interactions mediated by herbivore-induced plant volatiles: variation in production of cues and in responses of predatory mites

Phytoseiid mites use herbivore-induced plant volatiles in long-range prey-habitat location and are arrested by these volatiles in a prey patch. The responses of predatory mites to these volatiles are considered to be an important factor in the local extermination of prey populations by phytoseiids such as Phytoseiulus persimilis. Prey-induced plant volatiles are highly detectable and can be reliable indicators of prey presence and prey identity. The composition of herbivore-induced plant volatiles depends on plant species and plant cultivar. Moreover, the composition may also vary with the herbivore species that infests a plant. The responses of phytoseiids to prey-induced plant volatiles from a specific plant-herbivore combination are highly variable. Causal factors include starvation, specific hunger, experience, pathogen infestation and the presence of competitors. Investigating variation in the phytoseiid's behavioural response in relation to these factors is important for understanding how and why behavioural strategies maximize phytoseiid fitness. (C) 1998 Chapman & Hall Ltd.