Abstract
The resistance status in Hyalomma ticks collected from animal farms in three different regions of the Emirate of Abu Dhabi (UAE) was estimated using adult immersion tests with various concentrations of cypermethrin (50ppm, 100 ppm, 200 ppm, 400ppm and 800 ppm). Regression graphs of tick mortality plotted against cypermethrin concentrations were utilized to determine lethal concentrations (LC<sub>50</sub> and LC<sub>90</sub>). The data generated on different life history variables (mortality, egg mass weight, reproductive index, and percent inhibition of oviposition) were used to assess the resistance status. Results revealed level III cypermethrin resistance in Hyalomma anatolicum of the Al Hamam region (Al Ain) and level II resistance in the Malaqet region (Al Ain), whereas level I resistance was observed in the other studied locations, except Sweihan (Al Ain) where the tick population was fully susceptible. The LC<sub>90</sub> value of susceptible (Sweihan) H. anatolicum was 244.87ppm and the discriminating dose (DC) was calculated to be 489.74ppm. The present study is the first report of cypermethrin resistance in ticks of the United Arab Emirates and highlights the need to further monitor resistance evolution during the implementation of tick control programs.