Compatibility of Phytoseiulus persimilis with Isaria fumosorosea against Two-Spotted Spider Mites (Tetranychus urticae) on Soybean

In this investigation, the impact of the predatory mite, Phytoseiulus persimilis (PM) and entomopathogenic fungus, Isaria fumosorosea (F) at three levels (F1=10⁴, F2=10⁶ and F3=10⁸ conidia/ml) alone or in grouping state as compared with Ortus (acaricide) was evaluated on eggs and motile stages of two-spotted spider mites (TSSM). Nine treatments (CK=control, F1, F2, F3, PM, F1+PM, F2+PM, F3+PM and Ortus) were performed. On the other hand, the effect of the used entomopathogenic fungus on numbers of eggs and motile stages of the predatory mite was detected only at four treatments (PM, PM+F1, PM+F2, and PM+F3). Applications of I. fumosorosea at all chosen doses caused significant decreases in the mean population density of TSSM eggs (50.15-58.81% in 2016 and 59.63-68.37% in 2017) and motile stages (62.61-74-66% in 2016 and 68.47-75.32%) in comparison to the control. The effect of PM addition on TSSM eggs was higher than that of I. fumosorosea using but on TSSM motile stages, the pattern differed. The combination of both I. fumosorosea and P. persimilis showed greater influence on TSSM eggs and motile stages than the use of I. fumosorosea or P. persimilis individually. Spraying I. fumosorosea with releasing P. persimilis led to small reductions in eggs (11.88-22.42% in 2016 and 7.86-21.73% in 2017), and motile stages (9.84-21.33% in 2016 and 6.75-17%) of P. persimilis. Results of this study concluded that the combination of entomopathogenic fungus, I. fumosorosea and predatory mite, P. persimilis was strongly succeeded in the biological control process of TSSM on soybean plants under field conditions.