Polycephalomyces phaothaiensis is a novel entomopathogenic fungi species found in Phitsanulok of Thailand and its biological activities were investigated. The mycelia of two strains, BCC78485 and BCC78486, were extracted with methanol and the media were partitioning extracted with ethyl acetate. The antimicrobial activities were determined by disc diffusion and broth dilution, and the antioxidant activity was tested by DPPH scavenging assay. The larvicidal bioassay was performed against mosquito, Aedes aegypti, blow fly, Chrysomya megacephala, and common house fly, Musca domestica. Results showed that ethyl acetate extracts exhibited antimicrobial activities on five tested organisms, while methanol extracts did not. All extracts had low antioxidant activity with IC50 >500 g/ml, and no activity against larvae and adult of both fly species at 2,500 ppm. The BCC78486 methanol extract showed the highest mosquito larvicidal activity with LC50 at 593.41 ppm. This study shows that the extracts from P. phaothaiensis are a potential source for further study on its antimicrobial and mosquito larvicidal activity.
