prey preference and switching behavior of amblyseius swirskii (acari: phytoseiidae) on greenhouse whitefly and two-spotted spider mite

greenhouse whitefly and two-spotted spider mite are two important pests on greenhouse crops. the polyphagous predatory mite amblyseius swirskii preys on both of these pests. in this research, predation of the predatory mite on different stages of both pests, prey stage preference of pests, prey preference and switching behavior of predator between preferred stage of greenhouse whitefly and two-spotted spider mite were investigated in laboratory conditions (25 ± 1°c, 70 ± 10% rh and 16l: 8d hour photoperiod). the preference index for each experiment was calculated by manly’s β index. results showed that, young instars (first and second instars) of greenhouse whitefly and non-sessile stages of spider mites (larvae, protonymph and deuonymph) were preferred stages. comparison of the mean preference index between young instars of greenhouse whitefly and protonymphs of two-spotted spider mite showed that this predator showed a significant preference to t. urticae. the variation in different ratio of preys had no effect on predatory mite preference so switching didn’t observed in a. swirskii.