Crusoé: mimicking nature’s language to repel mosquitoes
In conjunction with the Innovation Awards ceremony taking place in July, the University of Marseille is honoring its past winners. Today, we spotlight Claude Grison, recipient of the 2020–2021 Innovation Award. As director of the ChimEco laboratory, this chemist and her team have developed an innovative mosquito repellent using a blend of natural molecules that are harmless to humans. Named Crusoé, this repellent is directly inspired by the language of nature.
Claude Grison is the woman who whispers in the tiger mosquito’s ear. As director of the ChimEco laboratory for bio-inspired chemistry and ecological innovations (CNRS/University of Montpellier), the researcher embarked on this journey in 2017. At the time, frustrated herself by this insect that ruins our summer evenings, she noted that the repellents on the market were either ineffective or entirely chemical. “The most effective molecule to date was DEET. However, it is a chemical molecule ill-suited to the mosquito’s biology. And recent studies have shown that it can be harmful to health,” explains Claude Grison. Conversely, she also noted that, in this area, no one had yet drawn inspiration from how nature works. “We know how nature communicates when it comes to attraction, but I was surprised to see that the same reasoning hadn’t been applied to repulsion.”
100% bio-based and environmentally friendly
Straddling the line between sustainable chemistry and ecology, Claude Grison has therefore made it her mission to address this scientific oversight. “The mosquito has more than 100 olfactory receptors, and many other receptors are involved in chemical communication with its environment. The goal was therefore to develop a repellent designed using a combinatorial approach, in order to trigger a strong reaction, whether pleasant or unpleasant,” explains the researcher. Her goal at the time: to find the right combination of natural molecules so that they would be recognized by as many receptors as possible.
Following promising initial trials, the CNRS awarded her a grant of 140,000 euros to fund the project’s “pre-development” phase. “It turns out that one of the most effective natural repellents is also very scarce. So we had to synthesize it. And my challenge, to stay true to my values and my work, was to produce it using entirely natural processes. Our syntheses are based solely on plant materials. They are 100% bio-based and have no environmental impact, ” insists Claude Grison.
The ecocatalysis method
To achieve this, the ChimEco laboratory team used the ecocatalysis method, developed in-house by the researcher. The principle: “using the mineral resources of certain plants to transform them into catalysts.” This innovative process has been the subject of 36 patents and has earned Claude Grison numerous awards, including the CNRS Innovation Medal in 2014. Using this mechanism, the researchers conducted over 4,000 behavioral tests on more than 24,000 insects. To refine their mixture, they also carried out 300 molecular syntheses. These experiments were conducted at Vectopôle Sud, a consortium of nine partners (including CIRAD, the CNRS,IRD,EID, the University of Montpellier, andANSES).
Specifically, the tests involved placing 10 mosquitoes in a cup attached to a membrane coated with repellent on one side and animal blood on the other. After an hour, the mosquitoes were asleep; they were collected one by one and then squashed onto a sheet of paper so that the researchers could examine the number of blood spots—that is, the number of insects that had actually bitten the skin… “We worked nonstop for two and a half years, with almost no vacations, since mosquito behavior differs between winter and summer, ” explains Claude Grison. In short, it was intense work—and it quickly hit the mark. The researchers soon identified two combinations of molecules with very strong repellent effects. According to Claude Grison, this product, named Crusoé, is about 90% effective, compared to 55% for DEET under the study’s conditions. And it also shows great promise against tick bites…
“I wanted it to be useful to society”
In 2021, through her startup Bioinspir—which had previously focused on invasive plant species—Claude Grison partnered with Technofounders. Together, they co-founded a company called Laboratoire Bioprotection to produce and distribute Crusoé. “I wanted it to be useful to society, so we needed to find a partner who shared our ethics to bring the repellent to market. The CNRS and the University, co-owners of the patents on ecocatalysis, never stood in our way—quite the opposite,” says Claude Grison. From a more pragmatic standpoint, this partnership allowed her to round out her expertise in regulatory and administrative matters; “That was the only thing we were missing, ” adds the scientist, but it also enabled her to increase the company’s capital through CNRS Innovation, which facilitated this on behalf of the CNRS and the University of Marseille as part of a debt-for-equity swap.
That same year, the team also received support through the “Companies And Campus” call for proposals, launched as part of the University of Montpellier’s Muse program of excellence. The reward: an additional budget of 50,000 euros. This was a crucial boost as the team was finalizing the last details before bringing the product to market. “It was incredibly important. It allowed us to make progress on the regulatory side, but also to validate our formulation on wild mosquito strains in tropical regions,” explains Claude Grison.
Shortly thereafter, in just six months, Crusoé obtained Ecogarantie certification and made its way onto pharmacy shelves. Since then, more than 400,000 products have been sold in France and internationally. At the same time, Claude Grison has also been showered with awards for her famous patents. In 2022, for example, she received the European Inventor Award from the Patent Office, followed by the Influential Woman Award in the economics category in 2023. But between trophies, she never stopped working on the next project. Now, for instance, she aims to launch a version of Crusoé designed to repel bed bugs. With her team, she is also working to develop a diffusion technique for use in homes.