Role of metabolic enzymes in conferring resistance to synthetic pyrethroids, organophosphates, and phenylpyrazole compounds in Rhipicephalus microplus

ABSTRACTThe study was conducted to work out possible correlation of resistance with functional enzymes in tick isolates of Rhipicephalus microplus collected from two agro-climatic zones of Uttar Pradesh, India. Adult immersion test was adopted using previously established discriminating concentrations of synthetic pyrethroids (SP) (deltamethrin, cypermethrin), organophosphates (OP) (diazinon, coumaphos), and phenylpyrazole (fipronil) compounds against these isolates. Quantitative enzyme profiling of esterases, cytochrome P450, and glutathione S-transferase (GST) enzymes was done to correlate resistance and enzyme activity. All the four isolates were found to be resistant to SP having resistant factor (RF) of 2.9–18.05 and to one of the OP compounds, diazinon showing RF of 3.5–15.07 but susceptible to coumaphos (RF < 1.4). The RF values of the four isolates were also found between 0.8 and 1.36 showing susceptibility to phenylpyrazole compound (fipronil). The enzymatic profiling revealed elevation in β-este...