Detection of Malathion Resistance in Hyalomma anatolicum anatolicum from Bathinda District, Punjab.

OBJECTIVE: The resistance status against malathion in Hyalomma anatolicum anatolicum ticks collected from Bathinda district, Punjab, was evaluated by adult immersion test (AIT).

MATERIALS AND METHODS: Technical grade malathion was used for conduction of AIT with 2 min immersion time protocol. The regression graph of probit mortality of ticks was plotted against log values of increasing concentrations of malathion and was utilized for the determination of slope of mortality, LC50, LC95 (95% confidence interval [CI]) and resistance factor (RF). The reproductive parameters of treated ticks viz. egg mass weight, reproductive index (RI), and percentage inhibition of oviposition (% IO) were also studied.

RESULTS: The increasing concentration of malathion showed an upward trend in per cent tick mortality. The slope of mortality (95% CI) was 2.489 ± 0.719 (2.489 ± 0.719) and value of goodness of fit (R(2)) was 0.799. The LC50 (95% CI) and LC95 (95% CI) values were recorded as 9099.2 (8378.6-9881.7) and 41,511.3 (35,060.2-49,149.4) ppm, respectively, with RF as 16.60 indicating level II resistance status. A negative dose-dependent slope of egg mass weight (-91.79 ± 25.15 [-171.8 to -11.76]) was recorded as the survived ticks laid significantly (P = 0.0355) fewer eggs. The mean RI of treated ticks decreased with increasing concentrations of drug and the slope (95% CI) was -0.293 ± 0.059 (-0.482 to -0.105). Further, a dose-dependent significant increase (P = 0.0157) in the mean % IO was recorded in treated ticks.

CONCLUSIONS: The results of the current study would be useful in the formulation and implementation of effective tick strategies in the region.