author(s)
Arunkumara CG, Jagadish KS, Mohan M, Venkatesan T, Narayanaswamy KC and Anitha Peter

abstract
Laboratory bioassay was conducted to observe the susceptibility level of field collected population of cotton leafhopper Amrasca biguttula biguttula (Ishida) against imidacloprid, thiamethoxam, acephate and fipronil. The results revealed that higher LC₅₀ values were recorded for acephate (316.04 ppm) and fipronil (42.01 ppm). However imidacloprid (24.91 ppm) and thiamethoxam (30.67 ppm) were showed lower LC₅₀ values and were highly effective in managing the leafhopper population as compared to that of other insecticides. Resistance ratios (RRs) were 4.67 fold for acephate, 3.15 fold for fipronil, 3.12 thiamethoxam and 2.06 folds for imidacloprid in field collected population of A. biguttula biguttula compared to the susceptible laboratory reared population.