Female mosquitoes detect a distinctive concoction of body scents humans release into the atmosphere while they are searching for a human to bite. The mosquitoes’ antenna receptors are then activated by these odours. To make people invisible to mosquitoes, researchers have attempted eliminating these receptors
However, mosquitoes still manage to bite us despite having an entire family of odor-sensing receptors removed from their genome.
According to a study that appeared in the journal Cell, mosquitoes have developed redundant fail-safes in their olfactory system to ensure that they can always detect our odours.
Margo Herre, a researcher at Rockefeller University and one of the paper’s lead authors, claimed that mosquitoes “are defying all of our beloved norms of how animals sense things.”
An olfactory neuron in the majority of animals is only capable of detecting one kind of odour. According to lead author Leslie Vosshall of the Howard Hughes Medical Institute and professor at Rockefeller University, “. If you’re a human and you lose a single odourant receptor, all of the neurons that express that receptor would lose the ability to smell that smell.”
According to Meg Younger, a professor at Boston University and one of the paper’s primary authors, “this project really started unexpectedly when we were looking at how human odour was encoded in the mosquito brain.”
They discovered that amines, another class of chemical used by mosquitoes to search for humans, also excite neurons that are stimulated by the human odour 1-octen-3-ol.
This is odd because all known theories about how animals perceive smell state that neurons encode odours with restricted specificity, which implies that 1-octen-3-ol neurons shouldn’t be able to detect amines.
Unexpectedly, 1-octen-3-ol and amine receptor-detection neurons did not belong to discrete populations, claims Younger.
This may serve as a fail-safe, allowing all human-related scents to trigger “the human-detecting component” of the mosquito brain even if some receptors are missing.
In order to determine whether additional receptors are expressed by specific mosquito olfactory neurons, the scientists also used single-nucleus RNA sequencing. According to Olivia Goldman, another main author of the study, “the discovery gave us a comprehensive insight of precisely how common co-expression of receptors is in mosquitoes.”
According to Vosshall, other insects might have a comparable process. The Johns Hopkins University research team of Christopher Potter has discovered that fruit flies’ neurons co-express identical receptors. According to Vosshall, “This may be a general approach for insects that strongly rely on their sense of smell.”