This study should help manufacturers develop other types of insecticides that are more effective once morest mosquitoes.
memory of smells – Learning is very present in mosquitoes!
Although their brains are very small (200,000 neurons only), mosquitoes are actually very intelligent. At least when it comes to approaching their prey or avoiding threats, as shown in a new study by Seynabou Sougoufara of the Research Institute for Development (France) and Hanna Yorkston-Dives of the University by Keele(1).
After a series of experiments, the researchers concluded that, if exposed to a low (non-lethal) dose of insecticide, mosquitoes are able to understand that this substance is harmful to them. Thus, two species among the most dangerous mosquitoes for human health, Aedes aegypti and Culex quinquefasciatusseem able to memorize the odors of five insecticide molecules commonly used
In the future, when they smell this same smell, they take care to move away from it.
Can we conclude that spray insecticides are losing their effectiveness? On the one hand, faced with a lethal dose (spray directly on the insect, as advised on the packaging by the manufacturers of insecticides), the mosquito dies immediately. On the other hand, if the exposure dose is not lethal, the mosquito will move away from the area where the insecticide was sprayed. People in other rooms or outside the dwelling will suffer the mosquito bites. In this sense, we can say that insecticides mosquito repellent are not fully effective.
Despite its tiny brain – around 200,000 neurons – the mosquito has a formidable sense of sight and sense of smell… in order to more easily locate its victims, animal or human – © Stokkete
Read also: A summer without mosquitoes
The design of new types of insecticides is necessary
The real question, however, is whether or not this acquired reflex to move away from the smell of the insecticide is transmitted from mother to mosquito daughter. To find out, more research needs to be done.
The other possible means of control would consist in modifying the active mechanism of the insecticides. The insecticides used today attack the nervous system of the insect.
However, as we see in this study, it is also the nervous system that protects them by ordering the mosquito to move away from the substance that is deadly for it.
Or, if the design of another active mechanism proves complicated, we might in the future design an insecticide with a delay effect : death would not occur suddenly but a few tens of minutes following exposure. In this way, the cognitive link between the smell and the discomfort would be broken.
Protection once morest mosquitoes is an important issue in tropical countries. Mosquitoes are indeed formidable disease propagators (dengue fever, yellow fever, chikungunya, zika, etc.).
The tiger mosquito is the deadliest animal for humans. A vector of deadly or serious diseases such as malaria, yellow fever, Chikungunya or the Zika virus, it kills around 725,000 people each year © Richard Juilliart / Shutterstock
The cases of these so-called diseases vectoriellles represent 17% of all cases of contagious diseases, and 80% of the world’s population is exposed to the risk of contracting at least one vector-borne disease.
Banner illustration: Aedes aegyptia mosquito dangerous to human health, is able to memorize the smells of five commonly used insecticide molecules – © frank60
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