Isolation and Identification of Bacteria from Batocera lineolata and Determination of Its Insecticidal Bioactivity

A red pigment-producing strain(BS–1) in the intestinal tract of Batocera lineolata, which died from natural diseases, was classified and identified by traditional microbial identification method and molecular technology; the virulence of the strain BS–1 suspension to the 5-d-old larvae of B. lineolata was determined by feeding method. The findings revealed that the strain BS–1 was identified as Serratia marcescens. On the basis of basal medium, the type and amount of other ingredient are sucrose 1%, yeast powder 6% and NaCl 1%. The best in vitro culture conditions are 35℃, pH 7, 240 rpm, and the culture time is 16 hours under the medium defined. The fresh bark of an iron walnut tree which was treated with 1.17 × 10¹¹ cfu/mL BS–1 suspension was fed to the larvae of B. lineolata, the infected body of B. lineolata gradually turned red and only the intestinal tract was abnormal. Finally, the corrected cumulative mortality rate was 100% after 15 days. The strain BS–1 in the intestinal tract of B. lineolata larvae which died from natural diseases was identified as S. marcescens, and the strains with insecticidal activity to its larvae. The results suggest that S. marcescens BS–1 which provide a basis for biological control of B. lineolata.