Functional response of Orius niger on healthy and Beauveria bassiana-treated two-spotted spider mite on cucumber

Study of behavioral parameters and functional response of predators is an important process in selecting these agents for biological control programs. In case of simultaneous use of these predatory insects with entomopathogens, behavioral reactions of predator may be altered. In this study, type of functional response of the predator, Orius niger (Hem.: Anthocoridae) was determined on the healthy adult female mite, Tetranychus urticae (Acari: Tetranychidae) and on the Beauveriabassiana-treated mites atthe four time intervals 0, 24, 48 and 72 hours at different densities of 5, 10, 20, 30, 40, 50 and 60 at 25 ± 1 ° C, 65 ± 5% RH and 16:8h (L:D) photoperiod. The results showed functional response of this predatory bug on untreated mites was type III while it was type II in other treatments. Comparison of searching efficiency and handling time in control with fungus treatments at various time intervals was only non-significant between control and 0 hour in searching efficiency and between control and 24 hours in handling time post-inoculation. The maximum attack rate (T/Th) in two treatments of 48 and 72 hours was reduced and was significantly different from other treatments; concomitantly handling time of predator was increased. These results suggest the effect of entomopathogenic fungus on behavioral reactions of predatory bug, O. niger.