| Studing the effect of sub-lethal concentration of thiamethoxam on Tetranychus urticae Koch using age stage two sex life table approach |
| Paper ID : 1013-3IICE (R1) |
| Authors: |
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Katayoon Kheradmand *1, Mohammadreza Havasi1, Hadi Mosallanejad2, Yaghoub Fathipour3 1Department of Entomology and Plant Pathology, Aburaihan Campus, University of Tehran, Pakdasht, Iran 2Iranian Research Institute of Plant Protection, Research Department of Pesticides, Tehran, Iran 3Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran, |
| Abstract: |
| Two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important pests on a wide range of crops in greenhouses and orchards worldwide. Control of T. urticae has been largely based on the use of acaricides. Unfortunately, repeated application of insecticides against this pest has caused many problems including resistance to insecticides. Therefore, studying on effects of pesticides with a novel mode of action against this pest is necessary.The present study assessed the sublethal effect of thiamethoxam (Actara®) in three concentration (LC5, LC10 and LC20) on life table parameters of T. urticae. The lethal and sub-lethal concentrations were calculated using bioassay experiments and leaf-dipping method. The primary population of the TSSM, collected from infested plants in the greenhouse of the Pakdasht (Tehran, Iran) and after identification, was grown on green bean plants. The experiment was performed in a growth chamber at 25±2 ºC, 60±5 % RH, and 16:8 h (L:D). The raw life history data was analyzed according to the age-stage, two-sex life table theory. Female longevity significantly reduced with increasing sub-lethal concentrations compared to control (ranged between 13.01 to 10.31 days).. The total mean number of eggs increased from 45.89 eggs / female (LC20) to 61.1 eggs / female (control) . In contrast, the reproduction parameters of TSSM including APOP, TPOP, were not significantly different among all concentrations. The intrinsic rate of increase (r) in LC5, LC10 and LC20 treated groups and control were 0.2348, 0.2326, 0.2308and 0.2340 day-1, respectively. The net reproduction rate (R0) in treatments of LC5, LC10 and LC20 were obtained as 48.59, 41.89 and 36.71 offspring / individual, respectively which showed a significant decrease in comparison with the control treatment (48.88 offspring / individual). The gross reproduction rate (GRR) of all chemical treatments (LC5=55.01, LC10=46.06 and LC20=41.52 offspring / individual) and control (54.01 offspring / individual) were not significantly different from each other. Finally, the finite rate (λ) of population growth in three concentrations were not significantly different . Moreover, mean generation time (T) in the control and LC5, LC10 and LC20 treatments were 16.61± 0.08, 16.53±0.09,16.05±0.09 and 15.60±0.07 days, respectively. In comparison to control, sublethal concentrations of thiamethoxam was harmful to the survival, longevity, and fecundity of T. urticae and could be further developed for use in integrated pest management of the TSSM in greenhouse production systems. |
| Keywords: |
| Tetranychusurticae, Sublethal effects, Thiamethoxam, Life tale |
| Status : Paper Accepted (Poster Presentation) |
