Phenotypic and genotypic characterization of dog tick Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) resistance to deltamethrin in Benin

The aim of this study was to evaluate the phenotypic and genotypic resistance of Rhipicephalus sanguineus sensu lato to deltamethrin in dogs in the municipality of Natitingou in Benin. In this study, the collection and identification of ticks, Larval Packet Test and specific allele PCR were the main methods used. A total of 41 dogs were examined and 420 ticks were collected in six areas which includes: Tchrimina, Yokossi, Boriyoure, Berecingou, Peporiyakou and Perma. Three species of ticks were identified and they include: R. sanguineus s.l., Rhipicephalus microplus and Haemaphysalis spp. However, R. sanguineus s.l. was the most abundant tick species (9.85) and had the highest parasitic intensity (10.36). The results of the Larval Packet Test showed that the larvae of R. sanguineus s.l. developed a phenotypic resistance against deltamethrin, particularly in the Berecingou area where resistance ratios of LC50 and LC95 of R. sanguineus s.l. compared to a susceptible strain were 1.591 (1.025-3.054) and 65.339 (20.235-579.825) respectively. The molecular study of the sodium channel gene revealed three genotypes namely the susceptible genotype (SS), the heterozygous genotype (SR) and the resistant genotype (RR), which correlates with the phenotypic results. This information is fundamental to improve monitoring and resistance management strategies of R. sanguineus s.l. ticks to pyrethroids.