اثرات زیرکشنده اسپیروتترامات روی پارامترهای رشد جمعیت کنه‌ی تارتن دو لکه‌ای Tetranychus urticae (Acari: Tetranychidae)

Two-spotted spider mite Tetranychus urticae Koch (Acari:Tetranychidae) is one of the most important pests of the greenhouses, farms and orchards in different regions of the world. Chemical control is one of the main methods to control this pest. Spirotetramat (Movento® SC 10%) is a tetramic acid derivative, has been used recently as a new pesticide for controlling sucking pests of agricultural crops. In this study, cucumber was used as a host plant for mite breeding and systemic method was performed for bioassay. Plants were sprayed by sub-lethal concentrations of Spiroteteramat, including LC10 (55.8), LC20 (100.2), LC30 (152.7μL /L) and control (distilled water). After 48 hours, the plant leaves were separated and prepared leaf discs. One hundred spider mites (protonymph) were placed in each treatment. Discs were placed under laboratory conditions (25 ± 2 oC, 65 ± 5% RH and a photoperiod of 16 L: 8 D) Subsequently. Also, at the third day of laying egg by females in the first generation, 100 eggs were randomly separated and mentioned parameters were recorded daily in both generations. Biological parameters such as longevity and fecundity was analyzed by using SAS software for the first generation and was performed according to the Age-Stage Two Sex Life Table theory for the second generation. According to the results obtained, duration of different life stages and fecundity of this pest was significantly affected by different treatments of Spirotetramat. So that in the first generation, developmental time was significantly increased from 6.33 (control) to 9.1 (LC30) days. Female and male (adult stage) longivity were decreased with increasing concentrations and in control with 16.77 and 14.95 days were the highest values and in LC30 with 10.08 and 10 days were the lowest values, respectively. The fecundity values of female were decreased from 43.02 (control) to 12.57 (LC30). In the second generation, the minimum developmental time was recorded for the control which showed a significant difference with the LC30. Also female and male longevity were decreased with increasing concentrations. The highest and lowest values of the intrinsic rate of increase (r) were recorded in control (0.185 day-1) and LC30 (0.77 day-1), respectively. Mean generation time (T) increased from 17.10 days in control to 21.47 days in LC30. The net reproductive rate (R0) was decreased from 23.88 in control to 5.33 (offspring/individuals) in LC30. The maximum finite rate of increase (λ) was recorded 1.20 day-1 in control treatment Whereas minimum value of this parameter was obtained 1.08 day-1 in LC30 treatment. The results showed that the sub-lethal effects of Spirotetramat on biological and population growth parameters of T. urticae were significant. Results of this study could be used in integrated management of this pest.