Effects of light on the tritrophic interaction between kidney bean plants, two-spotted spider mites and predatory mites, Amblyseius womersleyi (Acari: Phytoseiidae).

By analyzing the volatiles from Tetranychus urticae-infested kidney bean plants (Phaseolus vulgaris) at different times for two days, we found that they were mainly produced in the light. Tetranychus urticae showed a higher oviposition rate and spent more time feeding during the day (in the light) than at night (in the dark). Infested leaves placed in the light attracted the predatory mite Amblyseius womersleyi, whereas those that were placed in the dark for at least 2 h in daytime did not. This indicates that presence or absence of light affects the production of herbivore-induced plant volatiles. Amblyseius womersleyi dispersed more frequently and consumed more T. urticae eggs during the day (in the light) than at night (in the dark), whereas their oviposition rate did not differ between day and night. Presence or absence of herbivore-induced plant volatiles in the surroundings did not affect dispersal, predation or oviposition rates of A. womersleyi. These results show that A. womersleyi's behavior coincides with the production pattern of herbivore-induced plant volatiles.