Bio-larvicidal and Cytotoxic Activity of forest Streptomyces Isolate GA9 Against Some Mosquito Larvae

Abstract

An antibiotic-producing Streptomyces spp. was isolated from forest soil and assessed for its biolarvicidal and cytotoxic activity against various mosquito species (Aedes spp, Anopheles spp, Culex spp, and Mansonia spp) and Brime shrimps. Active biocides were extracted using a modified solid state fermentation process. Mosquito larvae were exposed to different concentrations of the ethanolic extract of the Streptomyces exudates for 24 hours. The extract's cytotoxicity was also evaluated using Brime shrimp. The results revealed a significant mortality rate among all four important vector mosquitoes following treatment with the extract. The LC50 and LC90 values of the extract were 0.40 mg/ml and 0.80 mg/ml for Anopheles spp, 0.20 mg/ml and 0.60 mg/ml for Culex spp, 0.40 mg/ml and 0.60 mg/ml for Aedes spp, and 0.20 mg/ml and 0.60 mg/ml for Mansonia spp, respectively. The Minimum larvicidal concentration values were 0.2 mg/ml for Aedes spp, Anopheles spp, Culex spp, and Mansonia spp. The extract showed a low degree of cytotoxicity, with an average mortality rate of only 20% at 0.8 mg/ml of the extract, upon testing with Brime shrimp. In conclusion, the aqueous extract of forest Streptomyces spp. exhibited high bio-larvicidal activity against Aedes spp, Anopheles spp, Culex spp, and Mansonia spp larvae, suggesting its potential as an environmentally friendly approach to mosquito control. This study represents an initial step toward supplementing eco-friendly nontoxic microbe-based bioinsecticides for synthetic insecticides against medically significant mosquitoes.