Assessing performance of <i>Amblyseius swirskii</i> as a predatory mite of <i>Tetranychus urticae</i> and <i>Frankliniella occidentalis</i> : life table and foraging behaviour studies

Life table parameters of Amblyseius swirskii when Frankliniella occidentalis and Tetranychus urticae were offered solely as diet were investigated. The switching behaviour of this predator was studied on F. occidentalis in the presence of spider mites. The data showed that feeding on the spider mite resulted in significantly longer developmental time compared to thrips. We found a significant effect of prey on the total life span, adult pre-oviposition period (APOP), and total pre-oviposition period (TPOP) of the predatory mite. The length of the oviposition period and the number of laid eggs per female were not affected by the kind of the offered prey. None of population growth parameters was affected by the type of diet except for mean generation time (T). Predators fed on spider mite had a longer T than those reared on thrips. Furthermore, our data illustrated a negative switching in the behaviour of A. swirskii when T. urticae and F. occidentalis were present. In other words, the predator switched from the abundant prey to the rarer prey. The results of this study are needed to understand and forecast the performance of A. swirskii in greenhouse environments where both T. urticae and F. occidentalis can be present.