Evaluation of Larvicidal Efficacy of Actinomycetes, Isolated from the Soil, against Dengue Vector, Aedes aegypti L.

Abstract

Soil samples were collected from various parts of Delhi and bacteria were isolated from collected soil samples through spread plate technique. The isolates were characterized based on their biochemical and morphological structures, and identified as Actinomycetes sp. The characterization of bacteria was confirmed according to Bergey’s Manual of Systematic Bacteriology.The larvicidal potential of isolated bacteria was assessed against dengue vector, Aedes aegypti using standard WHO protocol. Preliminary and quantitative larvicidal activity was performed against the early fourth instars of Aedes aegypti, maintained in the laboratory under controlled conditions of 28 ± 1 °C and 80 ± 5 % RH with a photoperiod of 14h daylight/10h darkness. The investigations prove the significant larvicidal efficacy of the bacterial isolate; Actinomycetes exhibiting LC50 values of 4.9 mg/mL and LC90 values of 11.7 mg/mL. The present study concludes that non-pathogenic bacteria present in the natural environment can be used as potential biocontrol agents against the larvae of Ae. aegypti. Further studies are needed to identify the bioactive secondary metabolite of bacteria effective against dengue vector larvae.