Resistance of the cattle tick Rhipicephalus microplus to alphacypermethrin, deltamethrin and amitraz in Côte d’Ivoire

Abstract

Cattle tick Rhipicephalus microplus has become a common problem for cattle herders in Côte d’Ivoire after its discovery there in the early 2000s, despite the availability of a large range of acaricide products. The objective of this study was to assess the resistance of the cattle tick R. microplus to alphacypermethrin, deltamethrin and amitraz, and to provide information to advice farmers of acaricide products choice in Côte d’Ivoire. A cross-sectional survey was conducted in September 2016 on nine farms where resistance to acaricides was suspected. Engorged R. microplus females were sampled and transported to the International Centre for Research and Development on Subhumid Livestock Production (CIRDES) in Burkina Faso. The FAO larval packet test method (adapted by CIRDES) was applied to assess the resistance-susceptibility level of the R. microplus tick populations to three common acaricidal molecules (alphacypermethrin, deltamethrin and amitraz) in Côte d’Ivoire. The results showed resistance ratios (RR) at 50% (RR50 95% CI) ranging from 0.26 (0.20-0.33) to 1910.3 (0.0-9063.3). High resistance to amitraz and deltamethrin was found on all farms, whereas resistance of tick populations to alphacypermethrin varied by farm from very susceptible to highly resistant. These results indicate that alphacypermetrin should remain a recommended acaricide on some farms in the country and underline the importance of raising awareness on the appropriate use of acaricides and monitoring acaricide resistance in tick populations in Côte d’Ivoire. Such actions will support farmers in the control and prevention of R. microplus infestation in cattle herds in Côte d’Ivoire.