Effect of plant extracts of Fumaria parviflora, Teucrium polium and insecticide pymetrozine on mortality and activity of esterase enzyme of Bemisia tabaci (Genn.) on resistant and susceptible variety of

In this research، the effect methanolic extracts of Fumaria parviflora، Teucrium polium and pesticide pymetrozine was assessed on the lethality and general esterase activity of adult Bemisia Tabaci (Genn.) at 27±2°C، 50±5 % RH and 16:8 (L: D) photoperiod. In bioassay experiments tomato plants of resistant (cal-j-n3) and susceptible (Ergon) cultivars with 2-4 leaves were immersed in different concentrations of plant extracts، and mortality was calculated 72 h after treatment. This study was conducted by using a randomized complete design with three replications. For each treatment، distilled water and methanol were used as control. To evaluate effects of treatments on esterase activity، seedling with 2-4 leaves are being thread with extracts and insecticides (LC25). The results showed that، the LC50 of the extract of F. parviflora، T. polium and pesticides pymetrozine for adults reared on susceptible and resistant cultivars، were، 17. 26، 93. 88، 0. 026 and 13. 26، 68. 36، 0. 019 (g/lit)، respectively. Sublethal effect of extracts and pesticides was significant on esterase enzyme activity compared to control. The amount of esterase enzymes، for control and adults treated with the extract of F. parviflora، T. Polium، pesticides pymetrozine on susceptible cultivar، were 0. 0161، 0. 0086، 0. 009، 0. 0038، respectively and for resistant cultivar were 0. 027، 0. 0068، 0. 0097، 0. 0043 (μg alpha naphtyl acetat per minute/mg protein) respectively. Thus the rate of toxicity of F. parviflora T. polium extracts، and pesticide pymetrozine was more insects that reared on resistant variety in comparison of adults that reared on susceptible variety. Also، pesticide Pymetrozine showed the most toxicity rate. The toxicity rate of F. Parviflora was recorded more than T. polium. Esterase enzyme activity was more in treated insects on resistant varieties compared to susceptible varieties. According to the results usage of resistant varieties with plant extract or pesticide can be a good strategy against whitefly in IPM programs.