Sublethal effects of diflovidazin on biological performance of two-spotted spider mite Tetranychus urticae (Acari: Tetranychidae)
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is one of the most important pests of agricultural crops with worldwide distribution that annually, imposes damage to different products. Chemical control is one of the main methods to control this pest despite its potential for resistance to different groups of pesticides. Assessing the effect of sublethal concentration of insecticides and acaricides to find their merit in integrated pest management (IPM) programs, is necessary. In this study, sublethal effects of different concentrations of diflovidazin including LC5, LC10, LC20 as well as control were evaluated on some biological parameters of T. urticae. The experiments were done under laboratory condition at 25 ± 2°C, 60 ± 5% RH and a photoperiod of 16: 8 (L:D) hours. A number of the offspring produced by each female per day was recorded until the death of the last mite. The data were analyzed based on the age-stage, two-sex life table procedure. The three sublethal concentrations were determined based on dose-response bioassay so that these levels were selected as 720 (543-888), 950 (745-1113) and 1300 (1087-1469) 𝜇g l-1, respectively. The results demonstrated that by increasing the experimental dose from LC10 to LC20, a significant decline was recorded in duration of biological maturation for both sexes of the two-spotted spider mite. Furthermore, in examining the traits of the total fecundity rate, it was found that under control, LC5, LC10 and LC20 treatments, the values were 61.1, 60.02, 44.8 and 38.9 eggs per day, respectively. The maximum and minimum values for the intrinsic rate of increase (r) were recorded to be 0.234 and 0.216 day-1 for the mites treated at control and LC20 concentrations, respectively. The net reproductive rate (R0) was decreased from 48.8 in control to 31.1 offspring/individuals in LC20 concentration. The finite rate of increase (λ), reached maximal value (1.263 day-1) in control, whereas minimum value (1.242 day-1) that was at LC20 concentration. The gross reproduction rate (GRR) was varied from 36.9 at LC20 concentration up to 54.01 offspring/individual at untreated mites. The recorded time period for the mean generation time (T), was variable from 16.6 days at control up to 15.8 days at LC20 concentrations. The results suggested that the sublethal effects of diflovidazin on some biological parameters of the two-spotted spider mite were significant, and the results of this study could be used in designing management programs for this noxious pest.
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