How the plant probiotic bacteria and herbivore-induced plant volatiles (HIPVs) alter functional response of Phytoseiulus persimilis (Phytoseiidae) on the two-spotted spider mite

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the economically most important pests on different crops worldwide. Its management programs are normally conducted based on the usage of chemical acaricides. However, considering the side effects of acaricides and rapid resistance development, releasing the predator mite, Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae), is an alternative method for the control of T. urticae. In this study, the effects of plant probiotic bacteria; Bacillus pumilus INR7 (Bacillales: Bacillaceae) and Bacillus velezensis Fol (Bacillales: Bacillaceae), and herbivore-induced plant volatiles (HIPVs) (methyl jasmonate, methyl salicylate, Indole and 3-pentanol) were investigated on the functional response of P. persimilis to T. urticae eggs laid on attached leaves of kidney bean under laboratory conditions (25 ± 1 °C, 65 ± 5% RH and a photoperiod of 16:8h L:D). Densities of 2, 5, 10, 20, 30, 40, 50 and 60 prey in 10 replications were offered to the 1-day-old adult female individuals of P. persimilis during a 24-h period. The results of logistic regression analyses showed a type II functional response on all treatments. The Rogers model was used to estimate the instantaneous attack rate (a) and handling time (Th). The instantaneous attack rate had no significant difference among treatments. The handling time on B. velezensis (0.3540 ± 0.0716 h) and methyl salicylate (0.3593 ± 0.0842 h) was significantly lower than in other treatments. These results suggest that methyl salicylate and B. velezensis may have a positive effect on the foraging behavior of P. persimilis against T. urticae.