Abstract: 【Aim】 To identify the effects of chlorogenic acid (CA) on the virulence of Lymantria dispar necleopolyhydrovirus (LdNPV) so as to provide information for the prevention and control of the gypsy moth, L. dispar. 【Methods】 CA+LdNPV and LdNPV were bioassayed using diet plus method, to determine the dose and time response of the 2nd instar larvae of L. dispar. 【Results】 CA+LdNPV and LdNPV differed significantly in dose and time response when they were tested against the L. dispar larvae. The median lethal concentration (LC₅₀) value of CA+LdNPV to the 2nd instar larvae was 161.8 OBs/μL (the 95% confidence limit was 105.6-235.3 OBs/μL), and that of LdNPV was 264.4 OBs/μL (the 95% confidence limit was 178.6-384.0 OBs/μL). CA+LdNPV was more virulent than LdNPV against L. dispar larvae. The median lethal time (LT₅₀) value of CA+LdNPV was shorter than that of LdNPV. The LT₅₀ values of CA+LdNPV and LdNPV were 9.9 and 12.3 days, respectively, at the concentration of 590 OBs/μL of LdNPV, and 6.9 and 8.0 days, respectively, at the concentration of 5 900 OBs/μL. The CA lowered the LC₅₀ value and shortened the LT₅₀ value of LdNPV against the 2nd instar larvae of L. dispar. 【Conclusion】 Chlorogenic acid enhances the virulence of LdNPV against the 2nd instar larvae of L. dispar, and its action mechanism needs further study.  

Key words:  Lymantria dispar, LdNPV, chlorogenic acid, virulence, median lethal concentration, median lethal time