The Influence of Host-Plant Resistance on the Efficacy of imidacloprid (SC 35%) against Developmental Stages of Bemisia tabaci Gennadius

The use of resistant plants in integrated pest management and its compatibilitywithchemicalcontrol measures has been emphasized in various studies. The effect of resistant cultivars on the efficacy of imidacloprid (SC 35%) was studied against eggs, nymphs and adults of the silver leaf whitefly, Bemisia tabaci (Gennadius) reared on Termus 14 (susceptible) and Okra (partially resistant) cotton cultivars under greenhouse conditions in 2013. Bioassays were conducted at 24±2°C, 65±5% R.H and a photoperiod of 16: 8 (L: D) using leaf- dipping method. The results indicated that mortality of all stages of B. tabaci was increased as a consequence of increase in the concentration of the insecticide. Toxicity of imidacloprid for all developmental stages of B. tabaci reared on partially resistant cultivar (Okra) was greater than those reared on Termus 14. The LC50 values of imidacloprid for the eggs, nymphs and adults reared on Termus 14 were 151.6 , 67.66 and 112.65 ppm, respectively. These values were determined for Okra as 135.78, 59.30 and 97.13 ppm, respectively. The results show a positive interaction between the use of partial resistant cotton cultivar to B. tabaci and imidacloprid. The results also show that the combined use of resistant plants and imidacloprid cause reduction of pesticide use to produce a given mortality rate. The results can be considered as the effective method for integrated management of B. tabaci.