Effect of chitosan solution on the bacterial septicemia disease of Bombyx mori (Lepidoptera: Bombycidae) caused by Serratia marcescens

The in vitro antibacterial properties of chitosan solution and its effect in protecting silkworms from bacterial septicemia disease were evaluated. The results showed that chitosan solution at concentrations of 0.01, 0.05 and 0.10 mg/ml exhibited strong antibacterial activity against two strains of Serratia marcescens. The antibacterial activity of chitosan solution against strain ZJS0801 of S. marcescens increased with the increase of chitosan concentration, while the antibacterial activity against strain ZJS0802 of S. marcescens was unaffected by chitosan concentration. The antibacterial activity of 0.10 mg/ml chitosan solution against S. marcescens increased with the increase of incubation time regardless of the tested strains. The mortality of larvae inoculated with the mixture of S. marcescens ZJS0801 and chitosan solution was significantly reduced compared to bacteria alone. In addition, the larvae mortality of silkworms inoculated with S. marcescens ZJS0801 was significantly reduced when silkworm larvae were fed on mulberry leaves treated with chitosan solution. Overall, the results indicated that chitosan solution had the potential for control of bacterial septicemia disease of silkworms.