Laboratory experiments conducted this week show that mosquitoes can be trained to associate the scent of DEET with a sugary food source [1].
This discovery suggests that insect behavior can be modified through conditioning, potentially altering how pests interact with chemical deterrents. While DEET is a global standard for protection, the study explores the limits of its effectiveness when mosquitoes learn to associate the chemical with a reward [1], [3].
Researchers used N,N-diethyl-meta-toluamide, commonly known as DEET, to test if mosquitoes could develop a preference for the repellent [2]. In a controlled laboratory setting, the team provided a sugary reward alongside the scent of the chemical [1], [3]. Following this training, some mosquitoes began to preferentially bite people who had been sprayed with the repellent [1].
"Trained mosquitoes learned to associate the smell of the repellent with food and actively sought out DEET‑covered skin," the researchers said [3].
The study was reported on Thursday, May 29, 2026 [1]. Despite the results, the research team said that the findings are limited to the specific conditions of the lab environment. The behavior observed does not suggest that DEET is failing in real-world scenarios.
"The results were found under very specific conditions in the lab and do not call into question the effectiveness of the repellent DEET," the lead study author said [1].
“"Trained mosquitoes learned to associate the smell of the repellent with food and actively sought out DEET‑covered skin,"”
The study demonstrates the capacity for Pavlovian learning in mosquitoes, showing that olfactory aversion can be overridden by positive reinforcement. While this does not invalidate the current use of DEET for public health, it provides a framework for understanding how insect populations might eventually adapt to chemical interventions through behavioral learning rather than genetic resistance.
