Malathion resistance in Rhipicephalus (Boophilus) microplus from Ludhiana district, Punjab.

The resistance status of Rhipicephalus (Boophilus) microplus collected from Noorpur Bet village of Ludhiana district, Punjab was evaluated against malathion by Adult Immersion Test. The adult female ticks showed an upward trend in the mortality percentage with increase in drug concentration. The regression graph of probit mortality of ticks plotted against log values of progressively increasing concentrations of malathion was utilized for the determination of slope of mortality (95 % confidence intervals) which was 2.469 ± 0.5744 (0.6413-4.297) whereas, the value of goodness of fit (R(2)) was 0.8603. The LC50 (95 % CI) and LC95 (95 % CI) were recorded as 1875.05 (1725.14-2,038) and 8,654 (7296.8-10263.8) ppm, respectively and the resistance factor was 3.46 (Level I). The slope of egg mass (95 % CI) was -0.1500 ± 0.04071 (-0.2795 to -0.02045) and was negative because with the increasing concentrations of acaricide the ticks died. The reproductive index when plotted against increasing log concentrations of malathion revealed a slope value of -0.414 ± 0.055. Further, a significant variation (p = 0.0049) was recorded in the inhibition of oviposition among the various groups treated with increasing concentrations of malathion.