Abstract: In order to explore the effects of variation in chemical substances in damaged masson pine (Pinus massoniana) needles, on population dynamics of Dendrolimus kikuchii, D. kikuchii larvae were reared with masson pine needles with different damage degrees caused by the pest in the laboratory, its population parameters and contents of nutrients and secondary substances in damaged masson pine needles were measured, and the integrated correlation coefficient was adopted for data analysis. The results showed that with the damage increasing in masson pine needles caused by D. kikuchii larvae, flavones in needles increased accordingly, while contents of soluble sugars, polysaccharides and proteins decreased. The average developmental duration and mortality of D. kikuchii larvae increased with the damage increasing. No significant correlation was found between the variation in contents of tannins or total phenols and the developmental duration or mortality of each instar larvae. There were significantly direct and comprehensive correlations between contents of nutrients and secondary substances of masson pine needles and the developmental duration or mortality of each instar larvae excluding 6th instar larvae. With the damage increasing in masson pine needles caused by D. kikuchii larvae, all parameters including body weight of 7th instar larvae, needle consumption, pupal weight, emergence rate, female ratio and fecundity in D. kikuchii population feeding the damaged masson pine needles decreased. No significant correlation was found between the variation in contents of tannins or total phenols and population parameters of D. kikuchii larvae. The results suggest that the contents of nutrients and secondary substances in masson pine needles dramatically influence the population parameters of D. kikuchii, with the importance sequence from high to low: soluble sugars>proteins>polysaccharides>flavones. Contents of tannins and total phenols seem to have no significant influence.

Key words: Dendrolimus kikuchii, Pinus massoniana, nutrients, secondary substances, population parameters, integrated correlation coefficient