Abstract:

During the transferring-damaging period of the overwinter larvae of Dioryctria pryeri, the terpene volatiles, the polyphenol oxidase (PPO), α-chymotrypsin inhibitor (ChymPI), and the free amino acid content, the crude fat and water content of Chinese Pine cones and (or) conelets induced by methyl jasmonate (MJA) and damaged by Gravitarmata margarotana larvae were examined. The results showed that the kinds of the monoterpene volatiles of the conelets and cones could not vary after damaged by the larvae of G. margarotana, but the content of the 6 monoterpene compounds in the infested cone and conelet obviously changed comparing with that in the uninfested cones, and the total content obviously increased. After the 2-year-old cone was damaged, the content of α-pinene, camphene, β-phellandrene and β-pinene decreases, while the content of β-myrcene and D-limonene increased, these changes of the cone volatiles could attract parasite wasps of G. maigarotana and D. pryeri larvae. After exogenous MJA treatment, the variation of the terpene volatiles in the conelet and cone were the same as the infested conelets and cones, but the varying extents were not very high. Meanwhile their PPO and ChymPI activity increased systemically after the conelet and cone was treated by exogenous MJA and damaged by G. maigarotana larvae, and the respone of the conelet to MJA treatment and insect-damage was more sensitive than that of the cone. 17 kinds of the free amino acid content changed, the water content decreased, the crude fat content increased after the cone was damaged. These results showed that the enzyme activity of resistance to nutrition and digestion in the infested cone increased, the nutritive quality decreased.

Key words: methyl jasmonate, Gravitarmata margarotana, Dioryctria pryeri, Chinese Pine cones, herbovire-induction