Isolation and identification of an entomopathogenic bacterium from aphids and preliminary study of its efficacy against Nilaparvata lugens

In order to obtain effective pathogenic microorganisms against Nilaparvata lugens, a highly virulent strain JSA1 was isolated from naturally infected cadavers of Rosa aphid by using the plate dilution coating method and flat crossed separation method. The strain JSA1 was primarily identified on the basis of its phenotypic, physiological and biochemical properties and 16S rDNA sequences analysis. Insecticidal activity of strain JSA1 was determined by using pot planting method and rice seedling dipping method. The results showed that strain JSA1 was primarily identified as Pseudomonas aeruginosa, and it exhibited insecticidal activity against N.lugens at different concentrations. The mortality of N.lugens increased as the concentration of strain JSA1 increased and the treatment time prolonged, but the mortality was less than 40%. The supernatant of fermentation broth and suspension of sonicated cell pellet of strain JSA1 showed significant insecticidal activity against the 3rd instar nymphs of N.lugens, with corrected mortality reached 30.72% and 82.53% after 72 h treatment, respectively. The results indicated that the strain JSA1 has potential in biological control of N.lugens.