ارزیابی اثرات زیرکشندگی کنه‌کش بایفنازیت روی پارامترهای شکارگری کنه‌ی شکارگر Phytoseiulus persimilis (Acari: Phytoseiidae) در شرایط آزمایشگاه

The two-spotted spider mite, Tetranychus urticae Koch, is one of the most important pests of different agro-ecosystems and since high feeding and reproductive potential and wide host plants range, causes severe damage to agricultural products, annually. The main combating method for control of this pest is chemical control and regarding undesirable effects of these compounds on environment and non-target organisms, search for alternative methods are urgently needed. Accordingly, application of integrated management programs using natural enemies and chemical pesticides are among the management strategies of this pest and their potential in suppression of population of T. urticae in different agro-ecosystems could be considered. The predatory mite Phytoseiulus persimilis Athias-Henriot is one the most important natural enemies of this pest worldwide and its feeding activity on different life stages of T. urticae has considerable role in decreasing its population density. In the present study, sublethal effects (LC10 = 21, LC20 = 52 and LC30 = 100 ppm) of Bifenazate (Floramite® 24% SC) on the predation parameters of this predatory mite was evaluated under laboratory conditions with 25 ± 1 ºC, relative humidity of 65 ± 5 % and a light period of 16 hour. Data analysis was performed using Age-Stage Two Sex Consumption Rate theory. According to the results obtained, the highest (99.05 ± 4.59 prey) and lowest (95.13 ± 4.06 prey) value of the net predation rate (C0) was calculated at control and LC30, respectively. The observed differences among the values of stable predation rate (ψ) at different treatments were not significantly different (control = 1.58 ± 0.06, LC10 = 1.54 ± 0.05, LC20 = 1.60 ± 0.07, LC30 = 1.58 ± 0.06, prey/predator). The highest calculated value of finite predation rate (ω) was estimated at control (2.15 ± 0.10 day-1) and the values of this parameter at treatments of LC10, LC20 and LC30 were 2.09 ± 0.09, 2.17 ± 0.10 and 2.16 ± 0.10 (day-1), respectively. Furthermore, our findings revealed that transformation rate from prey population to predator offspring (Qp) was not significantly affected (control = 2.84 ± 0.18, LC10 = 2.89 ± 0.16, LC20 = 2.74 ± 0.19 and LC30 = 2.64 ± 0.16 prey/predator offspring). The results obtained revealed that sublethal concentrations of Bifenazate had no adverse effects on the predation parameters of P. persimilis and hence, in management programs of T. urticae potential of simultaneous application of these two control procedures should be noticed. However, more attention should be devoted to evaluate this issue at greenhouse and field conditions.