Trending Now - Mosquitoes May Be Developing a Tolerance to Insect Repellents

WHO:

The Guardian - Prof Claudio Lazzari from the University of Tours, France; Dr. Nina Stanczyk of ETH Zürich university; Prof Francesca Romana Dani, an entomologist at the University of Florence.

WHAT:

The Guardian - A new study suggests that mosquitoes can learn to associate the presence of Deet with the possibility of a blood meal.

The Guardian - 60% of mosquitoes that fed when presented with warm blood alongside exposure to Deet subsequently showed biting attempts when exposed to Deet alone.

The Guardian - 17% of insects given no prior training attempted to bite Deet, 13% previously presented with Deet alone, 17% that previously fed on warm blood with no exposure to Deet, and 23% that previously fed on warm blood and were exposed to Deet but not simultaneously.

The Guardian - Almost 60% of mosquitoes that previously fed on blood while exposed to Deet attempted to bite a researcher’s Deet-treated hand, while untrained mosquitoes tried to bite the untreated hand.

WHERE:

The Guardian - Research conducted at the University of Tours, France; ETH Zürich university; University of Florence.

WHY:

The Guardian - The study indicates that mosquitoes can modify their reaction to repellents based on experience, similar to Pavlov’s dogs learning to associate a bell with food.

HOW:

The Guardian - The researchers observed trapped mosquitoes attempting to bite a bag of warm blood that they could not reach, leading to further investigation into their behavior with Deet.

The Guardian - The study was published in the Journal of Experimental Biology, detailing the methods used to assess mosquito behavior in relation to Deet exposure.

(UPDATED May 28, 2026 19:53 UTC)

A new study published in the Journal of Experimental Biology reveals that mosquitoes can learn to associate the presence of Deet with the opportunity for a blood meal, showing a significant behavioral shift. Researchers from the University of Tours, ETH Zürich, and the University of Florence found that nearly 60% of mosquitoes that had previously fed on blood while exposed to Deet attempted to bite a Deet-treated hand, compared to untrained mosquitoes that targeted an untreated hand. This research suggests that, much like Pavlov’s dogs, mosquitoes can modify their responses to repellents based on their experiences.