Acaricidal Properties of Herbal Extracts against Deltamethrin Resistant Multi-host Cattle Tick Hyalomma anatolicum

Background: Hyalomma ticks are the major ticks prevalent in Gujarat state which are mainly controlled with chemical acaricides. The control strategies are complicated by emergence of resistance against chemical acaricides. Development of resistance against these acaricides has compelled scientists to explore the acaricidal properties of constituents other than chemicals. Methods: Resistance status of Hyalomma anatolicum collected from Gujarat (India) against deltamethrin was assessed by larval packet test, which revealed level I resistance against deltamethrin. The crude ethanolic extracts of leaves of Cymbopogon citratus, Citrus aurantiifolia, Annona squamosa, Carica papaya and Catharanthus roseus were assessed for their acaricidal activity against larvae of deltamethrin resistant H. anatolicum. The efficacy was assessed by measuring per cent larval mortality and determination of LC50 values. Result: Various ethanolic extracts emanated a concentration dependent increase in larval tick mortality. The highest mortality (93.01 +/- 0.35%) was observed with the 100 mg/ml concentration of ethanolic extract of leaves of C. aurantiifolia. Overall, C. aurantifolia, A. squamosa and C. citratus were found to have significant acaricidal properties with LC95 values of 1.07x10(2) mg/ml, 6.09x10(2) mg/ml and 3.62x10(3) mg/ml respectively. Results of the present study indicated that these plant extracts have potential to be developed as herbal acaricides.