Attraction of the tropical bont tick, Amblyomma variegatum , to human breath and to the breath components acetone, NO and CO 2

Abstract

Ticks are of medical and veterinary importance and employ several cues in search of a host. Olfaction is one modality by which ticks locate a blood-meal and breath is the major vent of gaseous and volatile metabolites from the host that could contribute to this search. We studied the responses of a hunter tick, Amblyomma variegatum, to diluted human breath and five of its components (acetone, CO 2 , NO, isoprene and NH 3 ) while walking in an air stream on a locomotion compensator. Diluted breath elicited the greatest responses of all treatments in terms of time to onset of upwind walk, attraction, speed and local search behaviour after stimulus off. Acetone, NO and CO 2 also attracted, but with a reduced speed in the case of acetone and NO. Neither isoprene nor NH 3 induced any response. Our study indicates that breath was the most adequate stimulus tested. It also attracted two other ixodid tick species, Rhipicephalus sanguineus and Ixodes ricinus, as well as the argasid tick, Ornithodorus moubata. It appears that the evolution of resource tracking in ticks included sensory and behavioural adaptations for recognition and orientation to host metabolites that are regularly expelled in breath.

Evolution of the Gene Lineage Encoding the Carbon Dioxide Receptor in Insects

“…However, like other ticks the blacklegged tick uses CO 2 as a cue for the presence of vertebrate hosts (e.g. Holscher et al 1980; Schulze et al 1997; McMahon and Guerin 2002), so like honey bees they must use another method to detect carbon dioxide. This might involve other members of the chemoreceptor superfamily or it might involve a quite different mechanism like that reported in mammals (Hu et al 2007) or in the gustatory system of Drosophila flies (Fischler et al 2007).…”

Acarine attractants: Chemoreception, bioassay, chemistry and control

“…Behavioral assays have demonstrated the attractive quality of dermal pelage [106], host breath [105,107], gland secretions, and urine [105,108]. Acetone, ammonia, carbon dioxide, and 1-octen-3-ol (Table 4) are all attractive components of human and animal breath [36,109]. Carbon dioxide has long been recognized as an attractant for multiple species of ixodid ticks [107].…”

“…Sensilla cell responses to carbon dioxide have been recorded in A. americanum , A. maculatum , D. variabilis [110], and A. variegatum ticks [39]. Lab and field bioassays have also demonstrated the attractive quality of carbon dioxide to A. americanum [36], A. hebraeum [111], A. triguttatum [112], A. variegatum [109], D. andersoni [113], D. variabilis [36], I. dammini [113], I. ricinus [114], I. scapularis [115], R. microplus [28], and R. sanguineus [116]. Attractive behavioral responses to acetone and ammonia dissolved in water have been recorded for A. americanum [36] and to acetone alone in A. hebraeum [109].…”

“…Lab and field bioassays have also demonstrated the attractive quality of carbon dioxide to A. americanum [36], A. hebraeum [111], A. triguttatum [112], A. variegatum [109], D. andersoni [113], D. variabilis [36], I. dammini [113], I. ricinus [114], I. scapularis [115], R. microplus [28], and R. sanguineus [116]. Attractive behavioral responses to acetone and ammonia dissolved in water have been recorded for A. americanum [36] and to acetone alone in A. hebraeum [109]. Sensory cell responses to NH 3 [39,117] and acetone [109] have also been recorded in A. variegatum .…”

Chemosensory behaviors of parasites

“…For example, human-parasitic ticks, bed bugs, kissing bugs, and tsetse flies are attracted to host odorants such as CO 2 , 1-octen-3-ol, indole, lactic acid, and 4-methylphenol [89–98]. For some ectoparasites, such as the fish louse Argulus coregoni , the role of olfaction in host-seeking behavior is developmental stage specific: young A. coregoni rely primarily on visual cues for host location, while adult A. coregoni rely on a combination of visual and olfactory cues [99].…”