Preliminary Results of Larvicidal Activity and Phylogenic Analysis of Two Strains of Bacteria Isolated in the Demba Tiarki Tara Pond in Mali

Faced with the growing resistance of mosquitoes to conventional chemical insecticides, which are often very toxic to humans, it becomes imperative to find alternatives to organic products in order to reduce their nuisance. Actinomycetal bacteria and Bacillus are an opportunity because they have a great capacity for the production of active biological substances. The objective of this study was to isolate and verify the bacteria that produce larvicidal bioactive substances. Two bacteria were isolated from the soil of the DTT pond, tested the culture products on mosquito larvae and analyzed the genetic profile of the 16S rRNA gene. In culture, isolate S226 produced a larvicidal effect on Anopheles gambiae Kisumu of 8% and 14% death in the first hour, 24% and 32% at 48 hours with respective concentrations of 1.5% and 2.5 %. No adult form was visited within 48 hours of culture. As with isolate S296, larvicidal activity was observed at higher concentrations of 44, 46 and 42% for dilutions of 10, 20 and 25%, respectively. Phylogenetic analysis of the 16S rRNA gene from the two bacterial isolates shows that they are apparent to Bacillus and are unknown to the GenBank database. The S226 isolate is 100% similar and 97% identical to Pseudomonas hibiscicola, which of S296 is 100% similar and 95.98% identical to the genus Bacillus amyloliquefaciens. In conclusion, this pond contains microorganisms capable of producing bioactive substances on mosquito larvae. Further studies should be considered in order to better elucidate the active substances.