Effect of fibre polarity on the male compounds collected by SPME.

We compared the effect of fibre polarity on the male and female compounds collected by SPME, using an apolar carbowax/divinylbenzene StableFlex fibre (CW/DVB, 70 µm, Supelco, St Quentin-Fallavier, France) and a polar polydimethylsiloxane fibre (PDMS, 100 µm, Supelco, St Quentin-Fallavier, France). Both fibres were consecutively rubbed on the principal external parts of the same individual fly (head, thorax, wings, abdomen, genitalia). To avoid any effect of the first rubbing on the second SPME sampling, we swapped both sampling procedures as follows: Sampl. 1 & 2: first CW/DVB sampling on intact flies (Sampl. 1) followed by PDMS sampling (Sampl. 2); Sampl. 3 & 4: first PDMS sampling on intact flies (Sampl. 3) followed by CW/DVB sampling (Sampl. 4).
The SPME fibre was introduced into the GC-MS injection port as described in EXPERIMENTAL PROCEDURES.
Results are given as the mean (and SEM) of the relative amount of each compound (expressed in %). For each compound, the data obtained by the four sampling methods were compared using a Kruskal-Wallis test followed by Dunn's multiple pairwise comparisons (two-tailed with Bonferroni correction). Significant Kruskal-Wallis tests are shown by the K and p values, while the results of the subsequent Dunn's multiple pairwise comparison ares shown by the lowercase letters besides the relative amounts. The peak numbers and abbreviations refer to the compounds listed in Table 1.

本研究以固相微萃取（Solid Phase Microextraction，SPME）采集的雌雄果蝇化合物为研究对象，比较纤维极性对其采集效果的影响。所用纤维分别为非极性聚乙二醇/二乙烯基苯StableFlex纤维（CW/DVB，70 µm，Supelco公司，法国圣康坦-法拉维耶）与极性聚二甲基硅氧烷纤维（PDMS，100 µm，Supelco公司，法国圣康坦-法拉维耶）。将两根纤维依次擦拭同一只完整果蝇的主要外部躯体部位，包括头部、胸部、翅膀、腹部及外生殖器。为避免首次擦拭操作对后续固相微萃取采样造成干扰，我们对两种采样流程进行交叉设置，具体如下：样本1与样本2组：先采用CW/DVB纤维对完整果蝇进行采样（样本1），随后更换为PDMS纤维采样（样本2）；样本3与样本4组：先采用PDMS纤维对完整果蝇进行采样（样本3），随后更换为CW/DVB纤维采样（样本4）。
按照实验步骤所述方法，将固相微萃取纤维插入气相色谱-质谱联用仪（Gas Chromatography-Mass Spectrometry，GC-MS）进样口。
实验结果以各化合物相对含量的平均值及标准误（Standard Error of the Mean，SEM）表示，相对含量单位为百分比。针对每种化合物，我们采用克鲁斯卡尔-沃利斯检验（Kruskal-Wallis test）结合邓恩多重两两比较法（采用邦费罗尼校正的双侧检验），对四种采样方法获得的数据进行统计比较。克鲁斯卡尔-沃利斯检验的显著性结果通过K值与p值标注，后续邓恩多重两两比较的结果则通过相对含量旁的小写字母展示。峰序号与缩写对应表1中所列的化合物。