Crusoe: mimic the language of nature to repel mosquitoes

At the Innovation Awards ceremony in July, the UM honors its previous winners. Today, Claude Grison wins the 2020-2021 Innovation Award. Director of the ChimEco laboratory, this chemist and her team have developed an innovative mosquito repellent based on a bouquet 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 ear of the tiger mosquito. Director of the ChimEco laboratory for bio-inspired chemistry and ecological innovations (CNRS/University of Montpellier), the researcher embarked on her adventure in 2017. At the time, herself annoyed by this insect that spoils our summer evenings, she noted that the repellents on the market were either ineffective or entirely chemical. "Until now, the most effective molecule was DEET. But it's a chemical molecule that's poorly adapted to the way mosquitoes work. And recent studies have shown that it can be harmful to health", explains Claude Grison. On the other hand, she also notes that in this field, no-one had yet drawn inspiration from the way nature works. " We know how nature communicates in the field of attraction, but I was surprised to see that we didn't have the same reasoning for repulsion".

100% biosourced, with no environmental impact

Halfway between sustainable chemistry and ecology, Claude Grison has set herself the task of remedying this scientific blind spot. "The mosquito has over 100 olfactory receptors, and many others are involved in chemical communication with its environment. So we had to develop a repellent that could be designed in a combinatorial way, to trigger a strong reaction, whether pleasant or unpleasant", explains the researcher. Her goal at the time was to find the right composition of natural molecules to be recognized by as many receptors as possible. 

After promising initial trials, the CNRS granted him a 140,000 euro grant to finance the "premature" stage of the project. "One of nature's most repellent molecules also happens to be in very short supply. So we had to synthesize it. And my challenge, to be consistent with my values and my work, was that it should be obtained by completely natural processes. Our syntheses are based solely on plants. They are 100% biosourced and have no environmental impact," insists Claude Grison.

The ecocatalysis method

To achieve this, the ChimEco laboratory team used the ecocatalysis method, developed in situ by the researcher. The principle: "to use the mineral resources of certain plants to transform them into catalysts". This innovative process is the subject of 36 patents, and has won Claude Grison numerous awards, including the CNRS Medal for Innovation in 2014. Using this mechanism, the researchers carried out over 4,000 behavioral tests on more than 24,000 insects. To refine their mixture, they also carried out 300 molecule syntheses. These experiments were carried out at the Vectopôle Sud, an entity bringing together 9 partners (including CIRAD, CNRS,IRD,EID, the University of Montpellier andAnses).

In concrete terms, the tests involved placing 10 mosquitoes in a beaker, next to a membrane covered with repellent on one side, and animal blood on the other. After an hour, the mosquitoes were put to sleep, sampled one by one, then crushed on a sheet of paper so that we could examine the number of bloodstains, i.e. the number of insects that had actually bitten the skin... "We worked non-stop for two and a half years, and virtually without vacations, since mosquito behavior is not the same in winter and summer", explains Claude Grison. All in all, an intense piece of work that quickly hit the bull's-eye. The researchers quickly identified two combinations of molecules with very strong repellent effects. According to Claude Grison, this product, called Crusoé, is 90% effective, compared with 55% for DEET under the conditions of the study. And it also shows great promise against tick bites...

"I wanted it to be useful to society".

In 2021, Claude Grison joined forces with Technofounders via his start-up Bioinspir, which had previously worked on invasive plant species. Together, they co-founded a company called Laboratoire bioprotection with a view to producing and distributing Crusoé. "I wanted it to be useful to society, so we had to find a partner with the same ethics as us to bring the repellent to market. The CNRS and the University, co-owners of the ecocatalysis patents, were never in the way, on the contrary", confides Claude Grison. From a more pragmatic point of view, this association enabled her to supplement her skills in regulatory and administrative aspects; "That was the only thing we lacked", adds the scientist, "but also to increase the company's capital thanks to CNRS Innovation, which made this possible in the name and on behalf of CNRS and UM through a debt set-off".

That same year, the team also benefited from support under the Companies And Campus call for projects, launched as part of the University of Montpellier's Muse program of excellence. The result: an additional budget of 50,000 euros. A crucial contribution at a time when the team was finalizing the last details before going to market. "It was really important. It enabled us to make progress on the regulatory side, but also to validate our composition on strains of wild mosquitoes in tropical zones" , explains Claude Grison.

In the space of just six months, Crusoé obtained Ecogarantie certification and took over the pharmaceutical shelves. Since then, over 400,000 products have been sold in France and abroad. At the same time, Claude Grison has 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 Woman of Influence Award in the economics category in 2023. But between trophies, she never stopped thinking about what's next. Now, for example, she aims to launch a version of Crusoe designed to keep bedbugs at bay. With her team, she is also trying to develop a home diffusion technique.