Abstract:Plant volatiles play an important role in host recognition and selection by insects. We used GC-MS analysis to determine the composition and concentration of volatiles from two year old Larix gmelinii seedlings using two collecting methods: cryogenic trapping pre-concentration and solid-phase microextraction (SPME). Larix gmelinii seedlings contained 70 compounds including terpenes, hydrocarbons, alcohols, ketones, and esters. The major compounds were terpenes including α-pinene, 4(10)-thujene, camphene, β-pinene, D-limonene and β-phellandrene, together comprising more than 75% of total volatiles. The compositions and concentrations of volatiles differed among stem, needle and bark tissues. Needles contained higher levels of saturated hydrocarbons, while more sesuiterpene, alcohol, ketone and ester were found in bark than in stem tissues. The presence of caryophyllene and α-humulene was readily detected in bark by using SPME. These compounds probably facilitate short-distance location of host plants by insects. Of two pre-treatment methods, we found the results from cryogenic trapping pre-concentration were most similar to the natural characteristics of Larix gmelinii volatiles. In the experiments with SPME, the characteristics of adsorbent fiber could affect the absorption of some compounds. More sesuiterpene and less hydrocarbon were detected with SPME than with cryogenic trapping pre-concentration. We hypothesize that the various co-existing volatiles differentially affected the effect of adsorbent fiber, further reducing the accuracy of detection by SPME. We found cryogenic trapping pre-concentration to be useful for qualitative and quantitative analyses of volatiles.