Mosquitoes may learn to associate DEET repellent with blood meals, altering behavior in lab conditions
Consensus Summary
A new study published in the *Journal of Experimental Biology* reveals that mosquitoes can learn to associate the smell of DEET, a common insect repellent, with blood meals through Pavlovian conditioning. Researchers at the University of Tours trained *Aedes aegypti* mosquitoes to link DEET with feeding opportunities, finding that 60% of trained mosquitoes later attempted to bite when exposed to DEET alone, compared to 17% of untrained mosquitoes. The study suggests that under specific lab conditions, DEETâs repellent properties may be overridden by learned associations, though experts emphasize this does not diminish its effectiveness in real-world use. Both sources agree that travelers should continue using DEET-based repellents as directed, reapplying regularly to maintain protection. The findings highlight the complex behavioral responses of mosquitoes, which may adapt to repellents over time, though further research is needed to understand how this applies in natural settings.
â Verified by 2+ sources
Key details reported by multiple sources:
- A study published in the *Journal of Experimental Biology* found that 60% of mosquitoes trained with DEET and blood subsequently attempted to bite when exposed to DEET alone, compared to 17% of untrained mosquitoes.
- DEET (N,N-diethyl-meta-toluamide) is a widely used insect repellent recommended by the UK Health Security Agency at 50% concentration for protection against mosquito bites.
- The study used *Aedes aegypti* mosquitoes, which can transmit dengue, yellow fever, Zika, and chikungunya, but not malaria.
- Experts emphasize that the findings do not mean DEET loses effectiveness in normal use, and travelers should continue using repellents as instructed.
- The study was led by Prof. Claudio Lazzari from the University of Tours, France.
- The research suggests mosquitoes can form associations between DEET and blood meals through Pavlovian conditioning.
Points of Difference
Details reported by only one source:
- The UK Health Security Agency recommends 50% DEET products as the first choice for protection against mosquito-borne diseases like dengue, Japanese encephalitis, malaria, and Zika.
- Dr. Nina Stanczyk of ETH ZĂźrich noted that the highest risk of association occurs when repellent starts to wear off, emphasizing the importance of reapplication.
- Prof. Francesca Romana Dani of the University of Florence suggested that under normal conditions, mosquitoes are unlikely to change their response to DEET due to varied repellent encounters and infrequent blood meals.
- The study found 23% of mosquitoes fed on blood and exposed to DEET (but not simultaneously) later attempted to bite when exposed to DEET alone.
- The study used sheepâs blood for training, though *Aedes aegypti* mosquitoes primarily feed on humans in the wild.
- The lab-bred mosquitoes used in the study had been in captivity since the 1960s, potentially differing from wild mosquitoes.
- Thomas Schmidt of the University of Sydney noted that wild mosquitoes may evade insecticides by flying above treated areas and returning later.
- The study found that mosquitoes trained with DEET and sugar also showed attraction to DEET alone, suggesting the association is not blood-specific.
- The experiment involved dipping a researcherâs hand in DEET and observing mosquito behavior, with trained mosquitoes attempting to bite the treated hand.
Contradictions
Conflicting information between sources:
- The Guardian states that 13% of mosquitoes previously exposed to DEET alone later attempted to bite when re-exposed, while ABC does not mention this specific percentage for that group.
- The Guardian mentions Japanese encephalitis as a mosquito-borne disease alongside dengue, malaria, and Zika, but ABC does not list it in its summary of diseases.
Source Articles
Mosquitoes can become attracted to insect repellant, study suggests
The insect may learn to associate the chemical Deet with a âblood mealâ, researchers say It is a spray used worldwide to protect humans from mosquito bites, but now research suggests Deet can become attractive to the insects if they associate it with feeding. Deet â which has the chemical name N,N-diethyl-meta-toluamide â is widely used in insect repellants, with the UK Health Security Agency recommending products with 50% Deet as the first choice to protect against mosquito bites. Continue read
Insect repellent may not always keep mozzies away, study suggests
Scientists have found that mosquitoes in the lab can be trained to connect the smell of a widely used repellent with food, but repellents are still the best way to protect yourself.