Cypermethrin resistance in Hyalomma anatolicum and Rhipicephalus microplus ticks of arid and semi-arid zone of Haryana, a northern state of India

Regular monitoring of the status of acaricide resistance in field ticks is the need of the hour. Synthetic pyrethroids (cypermethrin and deltamethrin) are most commonly used acaricides against field ticks. There is bulk of literature on development of deltamethrin resistance; however, scarce information is available regarding current status of cypermethrin efficacy against field ticks. In the present study, the cypermethrin resistance status in Rhipicephalus microplus and Hyalomma anatolicum ticks infesting cattle and buffaloes of five districts located in the Northern Indian state, Haryana was determined using larval packet test. The linear regression graphs of probit mortality of tick larvae were plotted against log concentrations of cypermethrin to determine the slope of mortality, LC50, LC95 and the resistance factor (RF).Seven isolates of R. microplus were found resistant with their RF ranges from 1.83 to 25.35, whereas, 5 isolates of H. anatolicum were recorded as resistant with their RF ranging from 1.54 to 2.56 indicating a slower pace of development of cypermethrin resistance in multi-host ticks. Jarwa isolate of R. microplus and Dhangar isolate of H. anatolicum was found susceptible (RF < 1.5) to cypermethrin. The RF values of Agroha and Siwani isolate of R. microplus (10.73 and 25.35) were much higher as compared to other isolates indicating an urgency to address the growing cypermethrin resistance problem at grassroots level. Data generated in the present technical program could be of enormous help in formulating a suitable strategy against ticks and tick-borne infections of humans and animals.