The effect of Beauveria bassiana on preference and switching behavior in Phytoseiulus persimilis (Acari: Phytoseiidae)

The two-spotted spider mite, Tetranychus urticae Koch, is one of the most important phytophagous pests where high reliance on chemical pesticides to subsidize its population density resulted in undesirable effects. The use of natural enemies could be considered promising in reducing the negative impacts of earlier methods. In the present study, the LC50 (1.3 × 107 spore/ml) of entomopathogenic fungus Beauveria bassiana (Bals.) Vuill. (strain MZ) was used in on a choice and no-choice predation test, feeding preference and switching behavior of predatory mite Phytoseiulus persimilis Athias-Henriot feeding on different life stages of the two-spotted spider mite (egg, larvae, protonymph, deutonymph, adult male and adult female) in laboratory condition. According to results obtained, in no-choice test (i.e. without B. bassiana), the highest predation rate of predatory mite was observed to egg stage (15.22 ± 0.57 egg). In the test (with B. bassiana), the highest predation rate was recorded on the larvae of T. urticae (4.90 ± 0.64 larvae). In choice test (without B. bassiana), the highest predation was observed on egg stage (14.75 ± 0.56 egg). In the test (with B. bassiana), the highest predation was recorded on larvae (9.90 ± 0.53 larvae). The highest calculated value of Manly’s β index (without B. bassiana) was obtained on egg stage (0.89 ± 0.03). The estimated value of this parameter after treatment of different stages of prey with B. bassiana had the highest value on larval stage (0.61 ± 0.05). Switching behavior of P. persimilis was not observed in both with and without B. bassiana conditions. The present findings revealed that while using two natural enemies simultaneously, more attention should be devoted to evaluate their possible interactions.