Sublethal toxicity of combination of Bacillus thuringiensis and ethanol extract of Delphinium linearilobum on Spodoptera exigua

محمدی, داود and شریفی آذر, زهرا and شره مینی, مهتاب and عیوضیان کاری, ناصر Sublethal toxicity of combination of Bacillus thuringiensis and ethanol extract of Delphinium linearilobum on Spodoptera exigua. In: 2nd International and 6th National Iranian Congress on Organic vs. Conventional Agriculture, August 2019, Ardabil, Iran.

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Abstract

Integration of different control methods could decrease the adverse effects of synthetic pesticides and increase the efficiency of control methods (with lethal and sublethal toxicity) in IPM programs. In this study sublethal toxicity of microbial insecticide Bt and ethanol extract of Delphinium linearilobum were investigated. Extraction carried out by maceration method during 14 days. Different concentrations of Bt, plant extract and combination of them incorporated into artificial diet and disposed to 1st larval instars of beet army worm. Daily mortality was recorded until pupation in all treatments. The results revealed that, the rate of mortality in combined treatments was more than individual treatments and the most mortality was recorded in combination of highest concentration of both agents. The least LT50 values were calculated in combination of the highest concentration of both agents (1.85 days) and combination of the second concentration of Bt with first and second concentration of Extract (2.12 and 2.13 days respectively). The most synergistic effects were calculated in combination of the first concentrations of both agents while combination of the third concentrations showed additive effects. It seems that, combination of D. linearilobum extract with microbial pesticide, Bt, increased the efficiency of them in addition with decreasing the lethal time that is important in IPM programs.

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