Chemotaxonomy for female feeding stages of the diseases vector tick Rhipicephalus annulatus (Acari: Ixodidae) based on cuticle hydrocarbons

Abstract

Rhipicephalus annulatus is a vector of bovine babesiosis (cattle fever) and bovine anaplasmosis that infect approximately 80% of cattle production, leading to loss in the livestock and dairy industry. They are vectors of disease agents to humans. Cuticular hydrocarbons (CHCs) have been used as a chemotaxonomic tool to facilitate the identification of various arthropod species since the 1970s. The present study used GC-MS to differentiate the CH components of feeding stages of female R. annulatus. Hydrocarbons identified from the three stages contain 7 to 44 carbons and include linear strait-chained alkanes, and a few branched alkanes and alkenes. The chemical diversity was higher in an unfed stage and lower in an engorged one. The most abundant compounds across all stages were eicosane and tetracosane. Principal component and cluster analyses revealed that engorged stages were the most dissimilar stage in terms of their CHC profile, while the unfed and semi-fed stages showed relatively similar CHC profiles. The results obtained in this study demonstrated the potential use of CHCs to identify species, and different stages for female R. annulatus, determination of the most affected stage to be easily controlled, and establishment of a database to be used in chemotaxonomy of tick species.