Insecticidal Potential of Streptomyces spp. against Dengue Mosquito, Aedes aegypti Linn. (Diptera: Culicidae).

Aedes aegypti Linn. (Diptera: Culicidae) is one the most common vectors of disease-causing arboviruses such as dengue and chikungunya. The lack of vaccines for these diseases coupled with the current problem of increasing insecticide resistance intensifies the need to find novel and efficient ways of controlling the vector population. Hence, this paper aims to investigate the biological activity of Philippine Streptomyces isolates against Ae. aegypti as potential biological agents to manage the population of these mosquitoes. Prior to the testing of the biological activity, eight actinomycete isolates were identified based on morphological, cultural, and molecular characterizations using their 16S rRNA sequences. BLASTn results of the generated nucleotide sequences showed 98-100% similarity with different Streptomyces species and were assigned with the GenBank accession numbers MZ317443-MZ317450. Among the eight isolates, a CDC bottle bioassay of the extracted metabolites against 3 to 5-day old female Aedes aegypti adults revealed that CGS C13 (92.68%), DK 5-10 (85.53%), and CGS B11 (81.91%) showed the highest adulticidal activity statistically comparable to the positive control (abamectin). LC50 determination through dose-response bioassays showed that CGS B11 had the highest activity (2.838 ppm), followed by DK 5-10 (6.083 ppm) and CGS C13 (519.281 ppm). This is the first report on the insecticidal activity of these Streptomyces species against Ae. aegypti. [ABSTRACT FROM AUTHOR]