نامه انجمن حشرهشناسی ایران (Nov 2013)
Lethal and sublethal effects of dinotefuran and thiamethoxam on the population growth parameters of the green lacewing, Chrysoperla carnea (Neu.: Chrysopidae), under laboratory conditions
Abstract
The green lacewing, Chrysoperla carnea (Stephens), is a common natural enemy of various agricultural pestsand widely used as a biocontrol agent in integrated pest management (IPM) programs. The lethal and sublethal effects of the insecticides dinotefuran and thiamethoxam on the first instar larvae of C. carnea was assessed in the laboratory conditions at 25 ± 1°C, 60 ± 5% RH and a photoperiod of 16: 8 (L: D). The LC50 values for dinotefuran and thiamethoxam were 19.382 and 9.880 mg ai/l, respectively, that showed the high toxicity of thiamethoxam on the first instar larvae of C. carnea. To assess the sublethal effects, the first instar larvae were treated with the LC30 for dinotefuran and thiamethoxam at 3.532 and 1.692 mg ai/l, respectively. The estimated rm values in the control, dinotefuran and thiamethoxam were 0.185, 0.186 and 0.143 day-1, respectively. Finite rate of increase (λ) in the control, dinotefuran and thiamethoxam were 1.204, 1.204 and 1.154 day-1. Generation time and doubling time values in the control, dinotefuran and thiamethoxam were 30.77, 30.46 and 35.14 as well as 3.73, 3.72 and 4.82 days, respectively. The gross and net reproductive rates in the control, dinotefuran and thiamethoxam were 459.89, 439.08 and 309.42, and also 298.01, 278.45 and 155.03 (female/female/generation), respectively. Dinotefuran caused no significant adverse effects on the population growth parameters of C. carnea. If similar results are obtained for dinotefuran in the field, it might be an insecticide with low toxicity to C. carnea by using the reduced doses of the insecticide in IPM context. Studies under the laboratory conditions can help us to select some insecticides for additional studies under more natural conditions and for application of suitable insecticides along with natural enemies in pest management.
