Ionotropic and Gustatory Receptors Expressed in the Haller’s Organ of Male and Female Ixodes scapularis Ticks (Acari:Ixodidae)

For hematophagous arthropods, sensory organs capable of chemoperception are vital for finding a suitable host. The Haller's organ is a sensory structure unique to Ixodida that assists in host seeking behaviors. This structure is found only on the forelegs of ticks and is responsible for chemoperception of carbon dioxide, ammonia, and pheromones.  Using ILLUMINA transcriptomes we examined the expression of ionotropic (IR) and gustatory receptors (GR) in the forelegs versus hindlegs of male and female Ixodes scapularis ticks, as a proxy for identifying chemoreceptors likely to be expressed in the Haller’s organ.  We found two I. scapularis IRs to be expressed in the forelegs of these ticks and five GRs of interest.  This research aids in providing an increase in our knowledge of the Haller’s organ. The Haller’s organ is critical to the performance ability of tick activities, including host location, therefore improved knowledge of the Haller’s organ may facilitate tick management.