## 3 Results
### Characterization of Volatiles from Different Parts of A. altissima  
The volatiles from phloem from healthy and infested trees were collected by HS-SPME. Twenty-three and thirty-five components were identified in the volatiles of phloem from healthy and injured tree, respectively. There were more types of compounds in the volatiles of phloem from injured trees than from healthy trees (Table 1). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Number**} & \multirow{2}{*}{**Name**} & \multirow{2}{*}{**CAS**} & \multicolumn{2}{c}{**Area under Peak**} \\ \cline{3-5}  & & & **Healthy phloem** & **Injured Phloem** \\ \hline
1 & (1\(R\))-(+)-\(\alpha\)-Pinee & 7785-70-8 & 599,387 & 302,479 \\
2 & Camphene & 79-92-5 & 289,369 & \\
3 & \(\beta\)-Phellandrene & 555-10-2 & 78,859 & \\
4 & (15)-(\(-\))-\(\beta\)-Pinee & 18172-67-3 & 358,576 & \\
5 & Myrcene & 123-35-3 & & 1,360,591 \\
6 & (+)-(4\(R\))-Limonene & 5989-27-5 & & 1,898,791 \\
7 & \(\beta\)-Ocimene & 3338-55-4 & & 4,851,574 \\
8 & (+)-2-Carene & 554-61-0 & & 1,210,188 \\
9 & \(\alpha\)-Cubebene & 17699-14-8 & & 12,832,275 \\
10 & \(\beta\)-Copene & 3856-25-5 & & 10,567,644 \\
11 & \(\beta\)-Caryophyllene & 87-44-5 & 65,276 & 42,295,799 \\
12 & \(\alpha\)-Humulene & 6753-98-6 & & 7,472,179 \\
13 & \(\beta\)-Copane & & & 2,172,542 \\
14 & (+)-\(\delta\)-Cadinene & 483-76-1 & & 1,005,043 \\
15 & I-Calamenene & 483-77-2 & & 288,668 \\
16 & Caryophyllene oxide & 1139-30-6 & & 616,535 \\
17 & 2-Xylene & 95-47-6 & 184,083 & 1,196,424 \\
18 & \(p\)-Xylene & 106-42-3 & 332,852 & \\
19 & 1-Ethyl-4-methylbenzene & 622-96-8 & 68,356 & \\
20 & 3-Ethytoluene & 620-14-4 & & 972,029 \\
21 & 2-Ethytoluene & 611-14-3 & & 560,994 \\
22 & Mestiylen & 108-67-8 & 75,378 & 5,228,481 \\
23 & 1,2,3-Trimethylbenzene & 526-73-8 & 69,816 & 566,908 \\
24 & 1-Methyl-3-propylbenzene & 1074-43-7 & & 445,924 \\
25 & 2-Ethyl-p-xylene & 1758-88-9 & & 981,883 \\
26 & 4-Ethyl-m-xylene & 874-41-9 & & 785,844 \\
27 & 1,2,3,4-Tetramethylbenzene & 488-23-3 & & 520,840 \\
28 & 1,2,3,5-Tetramethylbenzene & 527-53-7 & & 864,315 \\
29 & 1,2,4,5-Tetramethylbenzene & 95-93-2 & & 303,672 \\
30 & 3-Methylcyclopentanol & 18729-48-1 & 159,700 & \\
31 & _cis_-3-Hexen-1-ol & 928-96-1 & 863,559 & \\
32 & Cyclohexanol & 108-93-0 & 333,474 & \\
33 & 1-Hexanol & 111-27-3 & 4,902,291 & 7,042,158 \\
34 & 2-Ethyl-1-hexanol & 104-76-7 & 515,699 & \\
35 & 3,3-Dimethyl-1,2-epoxybutane & 2245-30-9 & 1,169,014 & \\
36 & 2,4-Dimethylhexane & 589-43-5 & 110,544 & \\
37 & Tetradecane & 629-59-4 & 57,964 & \\
38 & \(d\)-Camphor & 464-49-3 & 59,699 & \\
39 & 2-Hendecanone & 112-12-9 & & 331,169 \\
40 & Tetradecanal & 124-25-4 & & 644,070 \\
41 & Pentadecanal & 2765-11-9 & & 286,561 \\
42 & Dibutyl ether & 142-96-1 & 1,178,162 & 1,392,083 \\
43 & 1,2-Dimethoxybenzene & 91-16-7 & & 540,650 \\
44 & Dibutyl phthalate & 84-74-2 & 272,435 & 554,530 \\
45 & Oxetane, 3-(1-methylethyl)- & 10317-7-6 & 85,020 & \\
46 & Di-tert-butyl peroxide & 110-05-4 & 119,142 & \\
47 & 4+Hydroxy-3-methylbutanal & 56805-34-6 & & 972,544 \\
48 & Acophyllene & 87745-31-1 & & 330,730 \\
49 & Cubebene & 13744-15-5 & & 2,455,168 \\
50 & (+)-Epi-bicyclosesquiphellandrene & 54274-73-6 & & 367,917 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Volatile compounds of healthy and injured phloem of _A. altissima_ by headspace solid phase microextraction (HS-SPME). A total of 43 compounds were identified from different parts of _A. altissima_ by dynamic headspace method. Fourteen volatile compounds were identified from phloem from healthy tree, and the main components of volatiles included \(\beta\)-caryophyllene (33.88%), 2-phenylethyl-1,1,2,2-d4-amine (17.52%), (\(-\))-camphene (8.22%) and 1-tridecanol (6.81%), accounting for 66.43% of the total amount. Twenty-two components were identified in the volatiles of phloem from injured tree, and the primary compounds were 1-tetradecene (17.58%), 1-tridecene (10.05%), \(\beta\)-copaene (8.94%), and n-hendecane (6.91%), accounting for 43.48% of the total amount.