Mosquitoes have started developing resistance to repellents, showed laboratory tests at the Swedish University of Agricultural Sciences (SLU) and associates in the UK and now new research suggests the process that makes mosquitoes able to ignore common insect repellents.
The findings of the research were published in the journal ‘Cell Reports’. The study says, unlike fruit flies, mosquitoes odour sensing nerve cells shut down those cells that produce odor-related proteins on the surface of the cells, thus no longer prompting them to fly from situations that smell dangerous.
The findings add to the research of how to better the composition of repellents to repel mosquitoes from human skin. It also reveals variation in the olfactory system from one insect to another.
Menace of mosquitoes has been a health concern among health authorities as they are responsible for spreading diseases like malaria, dengue, and some fatal ones like the Zika virus.
In this new research, Christopher Potter, associate professor of neuroscience at John Hopkins University School of Medicine establishes that mosquitoes are smarter than thought.
Other research on how receptors in insects respond to smell showed that odour receptors in flies’ olfactory neurons are abnormally expressed, sending a new signal to the brain and making it fly away from the offending odour.
Researchers in this experiment tested female Anopheles mosquitoes known for spreading malaria to find if these insects too can undergo a similar expression state that makes them move away from the place. Mosquitoes used were genetically modified to overexpress odour receptors. The purpose was to measure the neuron activity from the mosquito’s odour receptors. But to their surprise, it was found that the overexpressed receptors had very little response to scents of indole, benzaldehyde, or for chemicals odorants in general.
Researchers found the modified mosquitoes’ overexpressed receptors are able to ignore insect repellents in general. The researchers suspected that the cause of such response is that this may be a kind of failsafe in mosquitoes, ensuring that only one type of odorant receptor is expressed at a single time.
Researchers also suspect that in the case of Anopheles mosquitoes olfactory systems continue to develop into adulthood till eight days since hatching that its olfactory neurons might be susceptible to which olfactory receptors to express based on environment. Such flexibility of the inspects olfactory system makes it adapt to an environment with repellents.
Further research is being carried on to confirm the theory. Nevertheless, Potter says the findings will aid the search for methods that can trick the mosquitoes’ olfactory neurons to respond to all kinds of repellents.
