Abstract: Effects of infestation of the pine caterpillar,Dendrolimus puncatus and needle-cutting on the chemical components in the needles of Pinus massoniana were investigated for 10 days after treatment.Higher tannin content and lower contents of phenols and soluble sugars were found in the needles of the pine infested by the caterpillar than injured by needle-cutting,but the differences did not reach the significant level,indicating no obvious differences of these components during that term in response to the two injurious manners.The changes of nutritional material (soluble sugars) and secondary metabolites (tannin and phenols) in the needles of P.massoniana injured by infestation of the pine caterpillar or needle-cutting and in the needles of control pine were monitored for three successive years.It showed that contents of the secondary metabolites in the needles of the pine damaged by the two manners fluctuated along with time.They decreased in the first year after treatment and then went up to the normal level.Protein content in the needles of treatment pines was always higher than that in the control.Therefore,the induced chemical changes in the needles usually lag behind.

Key words: Pinus massoniana, Dendrolimus puncatus, injurious manner, induced chemical change, lagging occurrence