بررسی دوام اثر حشره کشی فرمولاسیون‌های مختلف حشره‌کش‌های ایمیداکلوپرید و لمداسای‌هالوترین تحت شرایط گلخانه‌ای

The green peach aphid, Myzus persicae Sulzer, is one of the most economically important plant pests worldwide. There are a number of factors that have made this species a serious pest, including its extensive distribution, broad host range, high reproductive capacity and transmission of viruses. The excessive use of chemical pesticides to control this pest has resulted in many environmental problems and resistance of this insect to several groups of insecticides. One of the strategies to overcome or delay the development of resistance is the use of mixtures of pesticides. Monitoring pesticide residues for appropriate management of the pest requires an understanding of the residual activity of pesticides and levels of control that can be achieved. In this study, residual activity of technical grade imidacloprid, lambda-cyhalothrin and their mixture (2:1 ratio, respectively) was assessed on M. persicae under greenhouse conditions (26±2°C, 60% RH and 16: 8 h (L: D) photoperiod) on bell pepper plants (California Wonder). The plants were sprayed with concentrations equivalent to LC85 of these insecticides (estimated using leaf dipping method). The estimated LC85 values were 51, 212 and 40 mg ai l- for imidacloprid, lambda-cyhalothrin and their mixture, respectively. The leaves were placed inside Petri-dishes; and up to 8 day old 20 adult aphids were transferred on them every other day and the mortalities were recorded after 48 h until the mortality rate reached zero. Each treatment consisted of at least 20 adult aphids and three replicates. In order to assess the possible effect of the adjuvants in the formulations on the residual activity, the plants were sprayed with mixture of commercial formulations and two controlled release nano formulations (prepared in laboratory conditions) with concentrations equivalent to LC85 of their mixture (40 mg ai l-). The results showed that the insecticidal activity of imidacloprid, lambda-cyhalothrin and their mixture reached zero 49, 23 and 27 days after treatment, respectively. Also, in studying of the effects of adjuvants, the persistence of commercial formulation increased from 27 to 35 days and those of their nano formulations increased from 27 to 31 and 39 days. Considering the life cycle of this pest (ca. 28-days), the nano formulation (31-day) showed appropriate persistence under greenhouse conditions.