Abstract:

GC-MS analysis was used to determine the composition and concentration of the terpene volatiles by means of XAD₂-absorption or CH₂Cl₂-extracts from uninfested and infested cones, and 1 year old needle of Pinus tabulaeformis and P. armandi during the oviposition period of female adult and the transferring-damage period of the overwinter larvae of Dioryctria pryeri. The results showed that the cone infested (by Gravitarmata margarotana larvae) of P. tabulaeformis contain 9 special terpene volatile compositions, α-pinene, β-phellandrene, β-pinene, β-myrcene, D-limonene, β-mentha-1,4(8)-diene, geraniol ester acetic acid, germacrene D and caryophyllene. After the cone was damaged, the content of the sesquiterpene constituents significantly decreases. However, there are 8 major volatile terpenes in the uninfested or infested cones of P. armandi, nohost tree species, during the period, the compositions and contents of both cones are obviously different to Chinese Pine. During the oviposition period, the compositions and contents of the uninfested and infested cones (by G. margarotana or D. pryeri larvae) of Chinese Pine have great difference, the special terpene compositions of the infested cone are α-pinene, β-phellandrene/4-thujene, β-myrcene, D-limonene, unidentified constituent, caryophyllene and α-caryophyllene. In the 1 year old needle, there are 8 special volatile terpenes, α-pinene, bornyl acetate, camphene, β-pinene, p-mentha-1(7),3-diene, unidentified constituent, caryophyllene and α-caryophyllene, comparing with the uninfested and infested cones. The results of selection and preference of the larvae showed that the larvae of D. pryeri obviously trend and select P. tabulaeformis cone to P. armandi cone, and in selection experiments of uninfested and infested cones, and their extract with CH₂Cl₂ of P. tabulaeformis, the larvae obviously trend and select G. margarotana-infested cone and its extract.

Key words: Dioryctria pryeri, host selection, plant volatiles