Native Metarhizium strains: kinetics of adhesion to the cuticle and their virulence against mosquitoes

Abstract Background : Malaria is a major public health concern in Burkina Faso, with over 90% of the country at risk of the disease. While malaria burden has declined in recent years, some fear it may be on the rise again due to resistance from the vector and parasite to existing control methods. Therefore, to stop malaria transmission in Burkina Faso and more broadly in endemic countries, it is necessary to implement new and complementary control tools, including the use of entomopathogenic fungi to control malaria vectors. Methods: Fungal strains were isolated from 201 insects and 1399 rhizosphere, and 4 strains of Metarhizium fungi were isolated. The fungal suspensions were used to infect 3-day old female Anopheles coluzzii mosquitoes at three different concentrations (10 6 , 10 7 , 10 8 conidia / mL). The survival of the mosquitoes was measured over 14 days and quantifying fungal growth after 1 and 24 hours assessed adhesion of the fungal strains on the mosquito cuticle.. Results: All four fungi strains increased mosquito mortality compared to control (p < 2.2-16). Adhesion of the fungal strains was observed on the mosquito cuticle after 24 hours at high concentrations, with one strain showing adhesion after just 1 hour and having the highest virulence. Conclusion: These results show that native Metarhizium spp. fungi are a promising tool for controlling malaria vectors. Some strains were effective enough to adhere to the mosquito cuticle at low concentration and showed high virulence. Further studies should screen additional native strains to establish the link between adhesion and virulence