Abstract: The concentrations of nutritional chemicals and secondary metabolites in new and old needles of Pinus massoniana following attack by Monochamus alternatus Hope and artificial damage were assayed. The results indicated that the levels of soluble sugars and rough polysaccharides in new and old needles fluctuated after treatments, but the concentrations in needles of P. massoniana fed by M. alternatus were less than those in needles injured by artificial damage. Treatments of both ways caused the decrease of protein and the increase of tannin and flavonoid in needles. The contents of protein decreaed at first after treatments of both ways, and began restoring to the control level 10 d after treatments. But the effects of feeding by M. alternatus were stronger than the treatment of artificial damage. Feeding by M. alternatus influenced strongly the content of tannin in new and old needles, whereas artificial damage had no influence on the content of tannin in old needles. After treatments by feeding and artificial damage, the contents of flavonoid in new and old needles were higher than that in the control, but the effect of feeding damage was stronger. These results suggested that the host P. massoniana had evolved special defense mechanism against the damage by M. alternatus.

Key words: Monochamus alternatus, Pinus massoniana, soluble saccharides, rough polysaccharides, protein, tannin, flavonoid