Molecular characterization of pyrethroids resistance mechanisms in field populations of Rhipicephalus microplus (Acari: Ixodidae) in district of Kpinnou and Opkara, Benin

Abstract

ABSTRACTThe tick Rhipicephalus microplus developed resistance against synthetic pyrethroid classes used for its control. The aim of this study was to characterize resistance of R. microplus for synthetic acaricides in order to establish an efficient control plan. The adult immersion test (AIT) was performed to test the susceptibility of R. microplus ticks to pyrethroids in two districts of Benin. Besides after DNA extraction from the tick larvae, a molecular identification test was done. Specific primers were used to determine the different mutations on the sodium channel gene in R. microplus population by PCR. AIT revealed a reproductive index of 0.02 ± 0.01 (p < 0.001) (Kpinnou) and 0.04 ± 0.02 (p < 0.03) (Opkara) with alphacypermethrin. Using deltamethrin, reproductive index was 0.24 ± 0.01 (p < 0.05) at Kpinnou and 0.10 ± 0.03 at Opkara, all at a concentration of 4 mg/ml. The resistance factors (RF) in the two districts were well above 41. The T2134A mutation was absent on the investigated farms. Regarding the C190A mutation, 86.67% and 56.67% of R. microplus larvae have resistant homozygotes in Kpinnou and Opkara, respectively. The introduction of new methods of tick control is essential to limit its population and control resistance.