As of July, the Saint -Denis Research and Development Institute plans to release 60,000 sterile and impregnated male mosquitoes – which do not bite humans – in the town of Saint -Joseph. If the results are effective after six months, for 18 months, the research center will drop the mosquitoes every week on 175 hectares. It will therefore be a total of 11 million male mosquitoes which will be released in the commune in the south of the island (photo: RB/www.imazpress.com)
It is to the insectarium of the Research and Development Institute (IRD) of the Cyclotron Indian Ocean Reunion (CYRO), that the teams of the Optis program raise the future sterile mosquitoes.
In this laboratory where heat and humidity reign, “the strains are high in mass. We put the larvae in water. We then separate the nymphs (corresponds to the stage of development between the larva and the adult) males and female”, explains Cécile Brengues.
“The males will be sterilized, some females will be used to renew the breeding,” she says. Insects sterilized by an X -ray irradator. Look
– “radiate” males in adult state –
They will also be covered with a chemical which consists in “radiating males in the adult state by impregnating them with an acid – the pyriproxyfen which prevents larval growth. Then they are released on the ground”, explains Cécile Brengues.
Once released, these mosquitoes “will go mounted with the wild females which will launch eggs but which will not hatch”, specifies the engineer.
If by chance, “the mosquito does not encounter females, the fact that it is imbued with biocides means that as soon as it will drink in the larval lodges, it will contaminate them,” she adds. Look
The OPTIS project (operationalization of the technique of the sterile insect against the Aedes vectors in Reunion) is a project co-supported by IRD and CIRAD and funded by Feder funds (Reunion and European Union region) as well as funds from the Ministry of Health and Research.
Read also – Sterile mosquitoes: a new insectarium inaugurated in Sainte -Clotilde
– 60,000 mosquitoes released by July in the south of the island –
first, 60,000 mosquitoes will be released on 60 hectares. Subsequently, the IRD teams will verify that “the impregnated mosquitoes have no effect on the environment, the fauna, the sentinel apia and the sentinel cottages”, explains Cécile Brengues.
“We will also dose the water of these lodgings to check the dosage of Pyriproxyfene (an acid preventing larval growth – Editor’s note) and if the rate is too high we will stop impregnating the mosquitoes and we will only release sterile mosquitoes,” adds the researcher.
If after these analyzes, all the lights are green, “we will let go of the mosquitoes permeated over 175 hectares, at the rate of 1,000 sterile mosquitoes per hectare, or an additional 175,000 during the 18 months”, informs Cécile Brengues. “So will be 11 million male mosquitoes that will be released,” said the IRD. Look.
A start that could seem late for the population while the epidemic has already contaminated more than 100,000 people in Reunion and caused at least nine deaths.
Read also – Chikungunya: 3,245 confirmed cases, the epidemic is maintained at a “high level of transmission”
If we want to let go of these insects “we need prefectural authorizations”, explains Cécile Brengues, research engineer, responsible for piloting the Optis project for the IRD.
“We obtained these authorizations in April and now we must investigate the method with the population of the town of Saint-Joseph,” she adds. Look
– 60% fertility reduction –
In 2021, tests were carried out in Sainte-Marie in the Duparc district. Only sterile mosquitoes (not impregnated) had been released. “The results have shown that 60% induced sterility had been obtained, but without significant drop in the density of mosquitoes. That is to say that mosquitoes were still very present,” said Cécile Brengues.
The IRD researcher does not have an illusion. “The technique of the sterile insect alone in Reunion is not sufficient. It is necessary to double an impregnation to endorse a decrease in the population, even if it means using the classic technique to maintain the population to a sufficiently low state,” said the engineer.
Read also – The technique of sterile insect reduces mosquito fertility up to 60%
Read also – dengue: Sterile mosquito releases, a viable solution to fight against the disease
– a large -scale project envisaged by 2026 –
If as from July, 6,000 sterile mosquitoes impregnated will be released in the wild for an experiment, developing this technique on a large scale remains a project.
For engineers, “you have to give research time. The idea of optis is not just to stop at 175 hectares. The idea is to transfer the technique to a Reunionese start-up already established on the island which will take over in 2026 and propose loose on a large scale”, indicates Cécile Brengues, head of the Optis project.
The “transfer to this start-up is the objective of showing that it works,” adds Thierry Baldet, a researcher entomologist at CIRAD, head of the Indian Ocean team and associated on this large-scale test project of the Sterile Insect technique.
Afterwards, “it is not a question of letting go of the mosquitoes on the whole island but in places judiciously chosen, the hot spots like towards schools, hospitals. It is a reasoned approach that we want,” he said.
The final objective being that this technique is “operational and available to prevent epidemics in the future”, adds Thierry Baldet. Those of chikungunya, dengue and even zika. Viruses all transmitted by the tiger mosquito, also called the Aedes Albopictus.
The first results of these releases will be known by the end of the year.
Read also – sprays, patches, spirals: against mosquitoes there is what works and what does not work
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Mosquitoes, chikungunya, IRD, health
