After three years of research and two international patents, 1.2 The composition of Crusoe has been optimized to combine effectiveness, duration and spectrum of action . Indeed, it is important to specify that Crusoe is a mosquito and tick repellent without any additives. It is notably Ecogarantie® certified.
- Crusoe, an extremely effective repellent against tiger mosquitoes of Mediterranean and tropical origin
More than 4000 behavioral tests were carried out at the Vectopôle Sud in Montpellier, 3 WHO collaborating centre, in order to evaluate the effectiveness of Crusoe. The Vectopôle is a research platform on vectors of pathogenic agents in public health, which has developed a cutting-edge method for testing mosquito repellents on a very large scale , without the need for tests on individuals. This method is a protocol that reproduces human testing conditions as closely as possible.
The test is based on the use of sheep blood kept at 37°C, placed in a feeder, from which female mosquitoes can feed by piercing a pig's intestinal skin, for 1 hour. The pig's skin may have been treated with a repellent to mimic human skin after spreading the mosquito repellent (Figure 1).
Figure 1: Behavioral tests assessing Crusoe's effectiveness
These experiments were conducted with tiger mosquitoes, Aedes albopictus , raised at the Vectopôle Sud in Montpellier. They made it possible to compare the effectiveness of Crusoe with DEET (the most widely used mosquito repellent in the world but also known for its potential toxicity), PMD (the reference for natural repellents) and ethanol (a negative control).
The results of the behavioral tests clearly show that Crusoe provided better repellency than DEET and PMD . Crusoe provided near-total repellency of tiger mosquitoes for 1 hour, with an average and highly reproducible efficacy of 83%, which is nearly twice as high as DEET and three times as high as PMD (Figure 2)
Figure 2: Results of behavioral tests on a Mediterranean strain of tiger mosquito breeding, for 1 hour. *ED50: 110mg/ m2 , † ED50: 200mp/ m2
However, it is known that farmed mosquitoes can have slightly different behavior and sensitivity than wild mosquitoes. Thus, other repellency tests were carried out with a tropical and wild strain from Madagascar in order to prove the effectiveness of Crusoe in a natural and tropical environment (Figure 3).
Crusoe again proved to be the best repellent with an average repellency of 77% for 1 hour, and far ahead of PMD which showed no action against this wild tiger mosquito.
Figure 3: Results of repellency tests on a wild tropical strain of the Madagascar Tiger Mosquito for 1 hour. † ED50: 200mg/m 2
- Crusoe, a broad-spectrum, long-lasting repellent
The effectiveness of Crusoe having been clearly demonstrated by behavioral tests on tiger mosquitoes, additional tests validated by the WHO (MPR: regulation (EU) n°528/2012) were able to be conducted on human volunteers by the TEC 4 laboratories.
These tests validated the repellent effectiveness of Crusoe compared to human blood using the "arm in the cage" technique. In addition, they allowed to determine the duration of action of Crusoe, which is a crucial and often problematic point when developing a new repellent. Indeed, there are a large number of very effective repellents, but for a relatively short duration (30min-1 hour), which can be dangerous for the consumer and requires repeated applications of the product.
Crusoe showed total repellent activity , i.e. no stings were observed for an average duration of more than 7 hours . It is also important to specify that this duration of 7 hours - 7 hours 30 of complete protection was affected by the tiger mosquito, Aedes albopictus , but also other disease-carrying species, Aedes aegypti , Culex pipiens And Anophele gambiae . These tests, validated by the WHO, have demonstrated that Crusoe is an excellent broad-spectrum mosquito repellent with long-lasting action.
- Crusoe, an effective tick repellent
Given the high number of tick bites, which are the leading vector of disease in Europe, Crusoe was also tested by the TEC Laboratory against the species of tick most widely present in France: Ixodes ricinus . Using the "arm in the cache" technique, Crusoe has proven total repellent effectiveness for an average duration of 5 hours against this species of ticks .
Claire Grison - Biochemistry Engineer, Doctor of Organic Chemistry and Scientific Editor
References:
[1] World Intellectual Property Organization, WO2021005214A1, 2021.
[2] World Intellectual Property Organization, WO2021005204A1, 2021.
[3] Vectopôle Sud Montpellier, http://www.vectopole-sud.fr/.
[4] TEC Laboratory - Efficacy tests on insecticide and repellent biocides. TEC Laboratory is approved by several ministries and works under Good Practices, https://www.teclabo.fr/.
