Effect of Bacillus thuringiensis var. kurstaki in combination with neemarin and silica nanoparticles in the control of second instar larvae of sugar beet, Spodoptera exigua Hb. (Lep.: Noctuidae) in laboratory condition

Bacillus thuringiensis var. kurstaki (Btk)is used for control of sugar beet army worm larvae, Spodoptera exigua Hb. in large-scale. Using high doses for more effective control increases the likelihood of developing resistance. The use of plant and physical compounds with this bacterium as an effective method to reduce the dose of Btk and increase its effect is of great importance and place in integrated pest management programs. Therefore, in order to reduce the use of Btk and increase its efficiency in mixing with silica nanoparticles and Neemarin to control the larvae of the second larval of sugar beet in labratory condition were evaluated. The LC50 value by probit analysis of different concentrations of Btk, silica nanoparticles and neemarin after 24, 48 and 72 hours (2252.39, 3219.22, 1608.15), (1483.31, 1852.49, 793.35) and (724.78, 982.28, 393.71) mg. L.-1 were obtained, respectively. The highest and lowest mortality in the treatment of Btk combination with neemarin (LC25, NE+LC25, Bt) (%66) and the control treatment (distilled water) (%2) after 75 h were observed. Also in the assessment of damage according to the mean of treatments, the most damage in the control treatment (%55.3) and the least damage in the treatment of Btk combination with neemarin (LC25, NE+LC25, Bt) (%15) after 5 day were obtained. In this study, due to the increase in Btk efficiency in combination with neemarin, the combination of these two factors in order to manage resistance and sustainable control of sugar beet army worm larvae and susceptible pests is recommended.