We have been using DEET to repel mosquitoes for years. The only problem is that, done poorly, it’s their favorite food.

DEET is one of the ingredients most used in mosquito repellents. That makes us think that, as its name suggests, it repels these insects. He doesn’t like it. However, according to a new study published by Virginia Tech scientists, under certain circumstances, that same substance could become an attractant for mosquitoes. These circumstances, basically, are what occur when we apply repellents without reading the label. Today is a good day to start reading it.

From repellent to attractant. These scientists they saw DEET generally repels mosquitoes. However, when they smell it while feeding, it can be associated with a reward. Something like what happened with Pavlov’s dog. When I heard the bell that was normally associated with mealtime, I would start to salivate. If mosquitoes smell DEET while feeding on blood, the next time they smell it they will associate it with food. And of course, they love that.

A painful experiment. The experiments that were carried out for the publication of this study consisted of two phases. First, mosquitoes of the species Aedes aegypty in a cage connected to two bottles, one with clean air and one with DEET. Inside the cage there was a feeder with blood, from which they could have fed in two circumstances. First, with access only to the clean air vial and then with the DEET vial open, since the second vial was opened while they were feeding.

In the second phase of the experiment, one of the researchers put his two arms into the cage, one with DEET and one without, and waited to see the behavior of the mosquitoes. Those who had blood-fed only with clean air went only to the arm without DEET. However, those who ate under the influence of DEET they preferred the arm with the repellent.

just a little. In reality, the repellent effect of DEET is a reality. At adequate doses, it continues to repel mosquitoes. What has been seen in this study is that it becomes an attractive when they smell it in the background while feeding. Therefore, the problem is allowing them to feed while they smell it.

A person who has too little, either because they have not applied enough repellent or because they applied it a long time ago, may not adequately repel the insect. It reaches your skin and feeds on your blood, while smelling a remnant. This remnant generates the aforementioned reward effect and, then, little by little you may stop disliking it. If every time we smelled the garbage they gave us 10,000 euros, would we still find it unpleasant?

The importance of reading the label. Not all mosquito repellents have the same concentration of DEET. Therefore, you do not always have to apply the same amount or reapply at the same time. It is important to read the label, because if we use too little repellent or do not reapply it when necessary, we can generate the effect that was seen in the study.

It’s not entirely clear. It should be noted that all this is not safe. This was seen in laboratory experiments. For now, it cannot be known if in reality, with DEET included in commercial repellents and mosquitoes flying freely, the same will happen. Furthermore, in the experiment the mosquitoes began to smell the DEET while they were already feeding whereas in real conditions the smell would be there from the beginning. More studies will have to be done, perhaps again with painful consequences for researchers and volunteers. Meanwhile, when in doubt, remember to read the labels carefully. Oh really.

Images | NIAID

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