Isolation, identification and insecticidal activity determination of a pathogenic bacterium Acinetobacter soli from Sogatella furcifera

The white-backed planthopper (Sogatella furcifera) is a significant pest of rice, inflicting severe damage to crops through feeding and transmitting of viral diseases. Therefore, developing and utilizing pathogenic microorganisms for the management of S. furcifera holds substantial practical importance. In this study, a bacterial strain, designated as HUNAN-1, was isolated from S. furcifera. The strain was identified using morphological and molecular biological approaches, and the insecticidal activity of its suspension against S. furcifera was determined by a spray method under laboratory conditions; the influence of fermentation time and pH value on the insecticidal activity of the fermentation supernatant were also evaluated. The results revealed that strain HUNAN-1 belongs to the genus Acinetobacter and was identified as Acinetobacter soli. This strain exhibited notable insecticidal effects against S. furcifera, achieving a cumulative corrected mortality rate of 100% at a concentration of 10⁹ CFU/mL, with an LT₅₀ value of 31.523 hours. Additionally, the LC₅₀ value was determined to be 2.71 × 10⁶ CFU/mL. The fermentation supernatant of strain HUNAN-1 demonstrated high lethality against S. furcifera, with mortality rates exceeding 80% after 72 hours of treatment. Notably, variations in fermentation duration and medium pH had no significant impact on the insecticidal activity of fermentation supernatant. In conclusion, strain HUNAN-1 shows considerable control potential of S. furcifera, with broad application prospects.