Larvicidal Effect of Spores and Metabolites Extracts of Aspergillus Fumigatus against Culex Mosquito Larvae

Abstract

Culex mosquito species are known to transmit diseases such as dengue fever, West Nile virus infection, malaria, lymphatic filariasis, and Japanese encephalitis. An estimated 120 million people suffer from mosquito-borne diseases across the globe. Repeated use of chemical insecticides has led to the emergence of insecticide resistance by Culex mosquito species, pollution of the environment, and harmful impacts on non-target organisms. The purpose of this study is to evaluate the larvicidal potential of metabolites and spore extracts of Aspergillus fumigatus against Culex mosquito. The fungal spore concentrations were ascertained after 5 days of fungal culture by optical density measurements. An equal amount of methanol and ethyl acetate was used to extract metabolites at four different test concentrations (10, 20, 30, and 40 mg/mL). The chemical constituents of the extracted metabolites were characterized using GC-MS and FTIR analyses. The protocols enshrined by WHO (2005) were followed in conducting the larvicidal bioassay, whereas the lethal concentrations (LC50 and LC90) were calculated by Probit analysis. The highest mortality rate (100%) was recorded at the highest concentration of metabolites extract (40 mg/mL) of Aspergillus fumigatus. Complete (100%) was recorded at spores concentration of 4.5× 10⁸ CFU/ml. The major bioactive compounds revealed by the GC-MS analysis include 9-eicosene, (E)-, 1-octadecene, 3-eicosene, (E)-, oleic acid, 1-nonadecene, cis-vaccenic acid, octadec-9-enoic acid, and squalene. The outcomes of this study showed that Aspergillus fumigatus metabolites and spores extract have the potential to control mosquito vectors. Hence, there is a need for large-scale production of bioactive components, as revealed by GC-MS analysis.