Detection of the status of acaricide resistance in Hyalomma dromedarii from nomadic camels of North Gujarat

The present study was undertaken to evaluate the efficacy of commonly used acaricides viz. deltamethrin, cypermethrin, flumethrin and fipronil against ticks infesting camels of north Gujarat. Larval packet test was conducted using field isolates of Hyalomma dromedarii for determination of 50 and 95% lethal concentration of deltamethrin, cypermethrin, flumethrin and fipronil. LC50 and LC95 values of deltamethrin (3.82, 35.36 ppm) and cypermethrin (6.59, 140.01 ppm) indicated the susceptibility of Hyalomma dromedarii larvae to these chemicals. Flumethrin and fipronil were found to be highly toxic to the larvae and thus, the LC50 and LC95 values were as low as 2.92x10(-8), 0.02 and 0.06, 1.62 ppm, respectively. Resistance characterisation revealed very low resistance factor in the ticks studied, i.e. 0.33 for deltamethrin, 0.03 for both cypermethrin and fipronil, respectively. Flumethrin recorded more than 99% mortality even at its lowest concentration. Multi-host life cycle and tick management practices without the use of chemicals might have protected these ticks from development of resistance.