we explain why all these precautions during mosquito-tiger operations

In recent weeks, the discovery of dengue fever has led to several mosquito control operations in Occitania. The most widely used insecticide is a pyrethroid, deltamethrin. Is it dangerous for humans? Response elements.

Mosquito control operations have multiplied this summer in Occitania, particularly in the former Midi-Pyrénées region. Blagnac or Montauban, for example, did not escape this. Whenever a case of indigenous dengue fever is detected, it is triggered.

It is the ARS that requires a (mandatory) mosquito control operation in the process. In Occitania it is dealt with by a private company that operates in the middle of the night. She uses Deltamethrin, an insecticide to treat a case of arbovirus such as dengue fever.

In France, insecticide families are very limitedexplains Grégory L’Ambert, medical entomologist at theEID-Mediterranean (Departmental Convention for Mosquito Control). APreviously, there were many products that had ecotoxicological profiles therefore unfavorable. ANSES has decided to retain two types of product that can be used exclusively and precisely for this type of operation, namely Deltamytrine, a synthetic product of pyrethrum, or natural pyrethrum. It’s the same thing. The molecule is extracted from the plant for one, the other is chemically synthesized in the laboratory.

During these exceptional mosquito control operations, residents are advised to take precautions: necessarily stay indoors, carry around on the terrace, close the windows, and even wait three days before consuming the fruit and vegetables of the house. ‘vegetable garden. be read in this document distributed to interested inhabitants.

These recommendations are far from reassuring for residents who wonder about the danger of the distributed product, while mosquito control agents wear masks and overalls. The topic is sensitive. No operator or organization wishes to comment on this question. So it is again Grégory L’Ambert fromEID-Méditerranée which replies on this point: “Deltamethrin is used in agriculture but also in mosquito reliefs, at doses suitable for the target species. This can vary between 5 and 12 g per hectare. We, for vector control, use it at one gram per hectare. Why this low dose? The goal is not to permanently disinfect. The goal is to have flash actions in a very short time.

Using the insecticide in too high proportions can, for example, deadly poison bee colonies located nearby.

For the entomologist, the risk therefore depends above all on the dose and its exposure time: “S.If you want to reduce the danger, you need to limit exposure. Hence a series of protection recommendations to limit their exposure as much as possible. Applying the recommendations of theConsideredLike us, these exposure measures have no health consequences. If you do exactly what you are told, there will be no problems. Our agents, on the other hand, are constantly in contact with this product, hence the protective measures. “

Deltamethrin is a very photolabile product : “as soon as you expose it to light, it degrades very quicklyIn the end, these recommendations to individuals during mosquito control operations are alone “LThe precautionary principle pushed to the limit with a product that offers no other alternatives.

Deltamethrin, the only usable insecticide in France, kills mosquitoes in a very short time. “The product acts on the nervous system, at the level of a channel that ensures the transmission of nerve impulses. The mosquito is eliminated and immediately dies“, explains Jean-Philippe David, researcher of the CNRS, who interested to the effects of this pyrethroid.

But deltamethrin has another drawback. If in metropolitan France the mosquito remains vulnerable to this product, over time it can become resistant to the insecticide. And it is precisely this knowing that the use of pyrethroid at a minimal dose is essential. “Fortunately, this insecticide is applied in the right proportions“underlines Jean-Philippe David. Because if the products were applied excessively,”resistant mosquitoes would become the majority“indicates the researcher. And there, it would not be the same story.

This is the case of the overseas. After decades of using deltamethrin, the insecticide has become ineffective at vector control. In New Caledonia, health authorities are forced to resort to malathion, an extremely toxic product that has been banned in France since 2008.

The best weapon to avoid this situation is prevention in order to allow the populations to fight as much as possible against the breeding sites.

Article written by Rémi Surrans with Sylvain Duchampt

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