Acute olfactory response of Culex mosquitoes to a human- and bird-derived attractant

Abstract

West Nile virus, which is transmitted by Culex mosquitoes while feeding on birds and humans, has emerged as the dominant vector borne disease in North America. We have identified natural compounds from humans and birds, which are detected with extreme sensitivity by olfactory receptor neurons (ORNs) on the antennae of Culex pipiens quinquefasciatus (Cx. quinquefasciatus). One of these semiochemicals, nonanal, dominates the odorant spectrum of pigeons, chickens, and humans from various ethnic backgrounds. We determined the specificity and sensitivity of all ORN types housed in different sensilla types on Cx. quinquefasciatus antennae. Here, we present a comprehensive map of all antennal ORNs coding natural ligands and their dose-response functions. Nonanal is detected by a large array of sensilla and is by far the most potent stimulus; thus, supporting the assumption that Cx. quinquefasciatus can smell humans and birds. Nonanal and CO2 synergize, thus, leading to significantly higher catches of Culex mosquitoes in traps baited with binary than in those with individual lures.bird odorants ͉ human odorants across different ethnicities ͉ nonanal-baited traps ͉ semiochemicals ͉ single sensillum recordings

Olfaction in vector-host interactions

“…It is interesting that odours, and specifically odour quality, ultimately are encoded by spatial patterns of activation in defined sets of glomeruli (Chapter 4). Such information needs to be linked to behavioural studies in which the behavioural response of insects to qualitatively different blends of odorants are being examined , Jawara et al 2009, Okumu et al 2010a, Syed and Leal 2009. Whereas in recent years significant advances have been made in our understanding of the olfactory processing of odour cues of vectors, there is a lack of congruence between these results and those of the behavioural essays reported elsewhere in this volume (Chapters 7 and 8).…”

“…Overlap in odour profiles of different blood-host species of a mosquito species, such as human and chicken, may reveal attractive compounds such as nonanal (Syed and Leal 2009). However, differences in these odour profiles may explain differences in relative attraction to these hosts due to allomones or additional kairomones (Dicke and Sabelis 1988) emitted by the host.…”

Crystal and solution structures of an odorant-binding protein from the southern house mosquito complexed with an oviposition pheromone

“…In the United States, they spread West Nile virus while feeding on birds and humans (1). In Africa, Culex quinquefasciatus is emerging as a major threat to bed-net programs.…”

Differential expression of olfactory genes in the southern house mosquito and insights into unique odorant receptor gene isoforms

“…The southern house mosquito, Culex pipiens quinquefasciatus (Cx. quinquefasciatus), is a significant bridge vector in urbanized centers in the Western United States, particularly southern California, due to its opportunistic feeding on avian and mammalian hosts, including humans (2,3). In general, female mosquitoes at some physiological stages in their adult life need to find (i) hosts (for a blood meal), (ii) suitable sites for oviposition, or (iii) plants to acquire energy for flights.…”