Do you still find yourself covered with mosquito bites during the summer, even applying insect repellent?
Scientists may have discovered the reason, as vicious insects have evolved the ability to detect human body odor in multiple ways.
The ‘olfactory receptors in the nose or antennae of most animals each sense a single, distinct scent particle.
The receptors are linked to ‘olfactory neurons’ that transfer information to the brain regarding a certain odor.
Researchers from Rockefeller University in New York, United States, have revealed that the neurons in the antennae of mosquitoes are related to various types of receptors.
This indicates that their neurons are stimulated by multiple chemicals produced by people, so even if one type of receptor is eliminated, they can still locate us.
Professor Leslie Vosshall, the study’s main author, stated, ‘You must exert more effort to eradicate mosquitoes because removing a single receptor has little effect.
Any future efforts to manage mosquitoes using repellents or other means must take into account how irresistible their attraction to humans is.
Professor Meg Younger of Boston University, the study’s lead author, stated, “This experiment began somewhat unexpectedly when we were investigating how human odor was encoded in the mosquito brain.”
The carbon dioxide we exhale and the compounds in our body odor, particularly 1-octen-3-ol and amines, allow mosquitoes to locate us.
The team of Professor Younger initially employed the gene-editing tool CRISPR to deactivate clusters of human-odor receptors on the antennae of female Aedes aegypti mosquitoes.
They anticipated that this would prevent their olfactory neurons from activating in response to the human fragrance.
When the neural activity was recorded while mosquitoes were exposed to human odor, it was discovered that the insects could still identify the odor.
Using RNA sequencing to determine what was happening on a cellular level, the researchers discovered that neurons triggered by 1-octen-3-ol are likewise stimulated by amines.
Consequently, the mixture of molecules in human odor was still able to stimulate olfactory neurons via receptors that had not been deactivated.
According to Vosshall, this may be a general technique for insects that rely significantly on their sense of smell.
It may also explain why insect repellents that operate by inhibiting a specific scent receptor are ineffective, as the insects’ neurons can still be activated by their other receptor types.
This contradicts all known principles about how animals smell, suggesting that mosquitoes acquired this skill as a failsafe for detecting human blood.
The findings, which were published today in Cell, show that removing their human-scent detectors via genome editing is not the most effective method for limiting the spread of mosquito-borne diseases such as malaria and yellow fever.
Instead, the scientists propose focusing on the development of more effective traps and repellents that take into account how mosquitoes interpret human odor.
Future studies will investigate why pests have acquired many receptors on single olfactory neurons in greater depth.
