Differential Attraction of Malaria Mosquitoes to Volatile Blends Produced by Human Skin Bacteria

Abstract

The malaria mosquito Anopheles gambiae sensu stricto is mainly guided by human odour components to find its blood host. Skin bacteria play an important role in the production of human body odour and when grown in vitro, skin bacteria produce volatiles that are attractive to A. gambiae. The role of single skin bacterial species in the production of volatiles that mediate the host-seeking behaviour of mosquitoes has remained largely unknown and is the subject of the present study. Headspace samples were taken to identify volatiles that mediate this behaviour. These volatiles could be used as mosquito attractants or repellents. Five commonly occurring species of skin bacteria were tested in an olfactometer for the production of volatiles that attract A. gambiae. Odour blends produced by some bacterial species were more attractive than blends produced by other species. In contrast to odours from the other bacterial species tested, odours produced by Pseudomonas aeruginosa were not attractive to A. gambiae. Headspace analysis of bacterial volatiles in combination with behavioural assays led to the identification of six compounds that elicited a behavioural effect in A. gambiae. Our results provide, to our knowledge, the first evidence for a role of selected bacterial species, common on the human skin, in determining the attractiveness of humans to malaria mosquitoes. This information will be used in the further development of a blend of semiochemicals for the manipulation of mosquito behaviour.

Attractiveness of volatiles from different body parts to the malaria mosquito Anopheles coluzzii is affected by deodorant compounds

“…coluzzii 2930. No inhibitory effect by any of the compounds of interest was found (ANOVA, P > 0.05, Supplementary Fig.…”

Host stress hormones alter vector feeding preferences, success, and productivity

“…We hypothesize that corticosterone affects many proximate mediators of vector feeding. For example, changes in volatile metabolites are associated with parasitic infection [41] and could alter host attractiveness [42]. Stress can also affect body odour [43][44] and may act on vector behaviours.…”

Insights into human evolution from ancient and contemporary microbiome studies

“…However, functional equivalence is called into question, as different ecotypes confer unequal susceptibility to bacterial vaginosis and sexually transmitted infections (STIs) [137••]. Likewise, volatile compounds produced by skin microbes have been found to influence mosquito attraction, and thus may play a role in malaria transmission [138, 139]. These observations have important implications for understanding virulence and disease transmission within a population, as well as strategies for personalized healthcare.…”

“…( a ) The oral microbiome a reservoir for numerous pathobionts and opportunistic pathogens [104, 105, 154]. ( b ) Skin microbiota influence mosquito attraction and may impact transmission of insect-borne diseases, such as malaria [138, 139]. ( c ) Bacterial inoculation of the breast assists infants with milk digestion [31]; breastmilk contains human-specific oligosaccharides that promote the growth of beneficial gut bacteria [45–47, 48••, 49].…”