Olfactory gene profiling in ticks: A scoping review with a functional perspective

Olfaction is important in ticks' host-seeking and mating behaviors, as it enables them to detect volatile chemical compounds. This scoping review aims to systematically map and synthesize the existing literature on olfactory gene families in ticks and to examine the application of functional genomics or behavioral approaches. We conducted a thorough search in five databases for publications up to 19 September 2025. This scoping review was implemented according to the Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. A total of 15 studies were included in this review, and 12 tick species were reported. Among these, Haemaphysalis longicornis and Ixodes scapularis had the most olfactory genes identified. Ten related olfactory gene families were identified in the 12 tick species. Among these, Niemann-Pick type C2 protein families were the most frequent across tick species (n = 11), followed by gustatory receptor and ionotropic receptor families (n = 7). Additionally, the studies reviewed found differences in gene family distributions among tick species. Molecular methods were used to identify olfactory genes, with most studies reporting RNA sequencing and reverse transcription quantitative PCR. A small number of studies used functional validation techniques such as RNA interference, ligand-binding assays, molecular docking, electroantennography, or Y-tube olfactometer assay. This scoping review highlights significant progress in the molecular understanding of tick olfaction. It emphasizes the importance of advancing this knowledge to improve comprehension of molecular tick olfactory and enable the development of targeted, olfaction-driven tick control and tick-borne disease prevention strategies.