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A new study has found that mosquitoes can learn to associate the smell of insect repellent with food and may later prefer to bite people wearing it under certain laboratory conditions, the researchers said on Thursday.
The researchers focused on DEET, the world’s most widely used insect repellent, which has been used since the 1940s to protect people from mosquito-borne diseases such as dengue, Zika, and yellow fever.
The lead researcher, Claudio Lazzari, said the findings do not mean DEET is ineffective.
“It is the absolute gold standard for repellents,” he said, adding that the World Health Organisation (WHO) still recommends it for protection against mosquito-borne illnesses.
During the experiment, scientists trained mosquitoes by repeatedly exposing them to warm blood and the smell of DEET. Later, the insects surprisingly moved toward the repellent scent even without blood present. In another test, trained mosquitoes preferred to land on a hand covered with DEET rather than on a clean hand.
Another researcher, Clement Vinauger, said the study changes how scientists understand repellents.
“What the insect has learned matters just as much as what the chemical does,” he explained.
The researchers stressed that the results happened under controlled laboratory conditions and advised people to continue using repellents properly. The study was published in the Journal of Experimental Biology.
