Interindividual variation in the attractiveness of human odours to the malaria mosquito Anopheles gambiae s. s.

Abstract

Differences between human individuals in their attractiveness to female mosquitoes have been reported repeatedly, but the underlying mechanisms are not well understood. Skin emanations from 27 human individuals, collected on glass marbles, were tested against ammonia in a dual-choice olfactometer to establish their degrees of attractiveness to anthropophilic Anopheles gambiae s.s. Giles (Diptera: Culicidae) mosquitoes. Ammonia was used as a standard odour source because of its proven attractiveness to An. gambiae s.s. Skin emanations from most volunteers attracted significantly more mosquitoes than ammonia. There were clear differences in the attractiveness of skin emanations from different volunteers relative to that of ammonia, as well as in the strength of the trap entry response. Consistent differences were observed when emanations from the three most and the three least attractive volunteers were tested pairwise. No gender or age effect was found for relative attractiveness or trap entry response. Emanations from volunteers with higher behavioural attractiveness elicited higher electroantennogram response amplitudes in two pairs, but in a third pair a higher electroantennogram response was found for the less attractive volunteer. These results confirm that odour contributes to the differences in attractiveness of humans to mosquitoes.

Olfaction in vector-host interactions

“…More recently several important studies have begun to unravel the olfactory physiology of An. gambiae antennae (Meijerink et al 2001, Meijerink and van Loon 1999, Qiu et al 2006. At the same time there is a growing appreciation of the antennal expression patterns of several genes that encode signal transduction components that have been linked in one degree or another to…”

“…gambiae and An. quadriannulatus Theobald were reported to respond to polar compounds such as ammonia, lactic acid, acetone, butylamine as well as to complex natural odour mixtures such as incubated sweat, cow odour and Limburger cheese odour, which Qiu et al 2006 4-methylcyclohexanol;4-methylphenol Bentley et al 1982 indole;phenols;1-hexen-3-ol;5-7C acids;3-methyl-1-butanol, ammonia 3-4C acids Qiu et al 2006 4-methylphenol; 4-ethylphenol; geranyl acetone; 2-nonanone; 1-hexen-3-ol; 1-hepten-3-ol; 1-octen-3-ol; 7-octenoic acid; 3-methyl-2-hexenoic acid; 3C, 3M4C,6C, 9C, 10C, 12C acids; oxo-4-5C acids; ammonia Qiu et al 2006 geranyl acetone, 3-methyl-1-butanol, sulcatone, ammonia, 2-6C acids; 1-octen-3-ol; 3-& Qiu et al 2006 ammonia; 1-butylamine; 2-oxo-butanoic acid; lactic acid 3-6C and 9C acids Qiu et al 2006 ammonia; 4-5C amines; 4-6C acids Qiu et al 2006 Olfaction in vector-host interactions Yu Tong Qiu and Joop J.A. van Loon is perceived by the human nose to resemble human foot odour (Meijerink et al 2001, Van den Broek andDen Otter 1999).…”

“…By testing the response of olfactory sensilla to a panel of 44 compounds that are components of human odour, plant volatile blends or derived from oviposition sites, Qiu et al (2006) identified four functional types among ST subtype C and two functional types among subtype E in female An. gambiae.…”

“…A tonic response is characterised by an increase in firing frequency that outlasts the duration of stimulation. The temporal response characteristics of an ORN to a certain stimulus seem largely independent of dosage (De Bruyne et al 2001, Qiu et al 2006). …”

Sandfly pheromones: Their biology and potential for use in control programs

“…Attraction to a host animal then is likely to be based on the balance between attractive and repellent elements in the animal's odour profile. In herds of Danish Holstein-Friesian cattle some are more attractive than others to Haematobia irritans (Hornfly) (Jensen et al, 2004), amongst humans there is considerable variation in attractiveness to female L. longipalpis based solely on the odours produced (Hamilton & Ramsoondar, 1994) and the variation in individual human attractiveness to mosquitoes has been well documented (Qiu et al, 2006). Carbon dioxide, plays a significant role in host finding, it is a major component of host breath, and activates and attracts several mosquito species (Gillies, 1980;Takken, 1991;Gibson & Torr, 1999).…”