Insecticidal activity of the metabolites of sand soil bacteria in Northern Senegal

Abstract BackgroundVector-borne deadly diseases cause more than 700,000 deaths annually. They are transmitted by several vectors, among which the mosquito is the most important. Chemical compounds often have devastating side effects, which has led to the abandonment of the majority of them. Biological control has been performed by using formulations of Bacillus sphaericus and Bacillus thuringiensis, but their intensive use has led to the emergence of resistance. Currently, there is an urgent need to develop new alterative molecules from bacteria to use in mosaics or in rotation with already known insecticides and bacteria for the control of vectors, especially mosquitos. Here, we attempted to identify bacterial species with potential anti-mosquito actions.ResultsAmong 208 strains isolated from dry sandy soil from Senegal, eleven bacterial strains from the Bacillus genus (5) and Actinomycetales order (6) were chosen for the following experiments. Then, we tested their secondary metabolites, which were obtained from the supernatant fraction, and their cell wall and cytoplasmic compounds, which were found in the pellet fraction, in 3rd and early 4th Aedes albopictus larvae instars and compared the larval mortality rate with that obtained by using a commercial product. A total of 4/11 (36.4%) of the isolated species exhibited insecticidal activity. B. nealsonii, which is not a well-known bacterium, had the highest larvicidal effect with 70% larval mortality, which highlighted for the first time. The Streptomyces spp. we isolated seem to be potential new species, and 3/5 (60%) of them exhibited insecticidal activity.ConclusionThe bacterial strains isolated in this study may be used to identify the molecular mechanisms of their insecticidal activity.