摘  要  【目的】 探究同花期的酥梨花和油菜花挥发性气味物质的种类和含量的差异，筛选影响蜜蜂采集偏好的挥发性气味物质，开发能刺激蜜蜂给梨树授粉的诱导剂，也为定向筛选梨树授粉蜜蜂品种提供理论依据。【方法】 利用顶空固相微萃取（Solid phase microextraction，SPME）和气相色谱-质谱联用技术（Gas chromatograph-mass spectrometer，GC-MS）分析砀山酥梨Pyrus bretschneideri cv. Dangshansu和甘蓝型油菜Brassica napus的花朵挥发性气味物质，然后利用触角电位技术（Electroantennography，EAG）和Y型嗅觉仪实验分析上述鉴定的气味物质对中华蜜蜂Apis cerana cerana （简称中蜂）和意大利蜜蜂Apis mellifera ligustica（简称意蜂）的影响。【结果】 梨花大蕾期、初绽期和盛开期鉴定出挥发性化合物均为52种，油菜花3个花期鉴定出挥发性化合物分别为73、73和69种；梨和油菜花3个花期中特有的挥发性气味物质分别为40和61种；它们共有挥发性气味物质为12种，梨花3个花期中乙偶姻和1,3-二叔丁基苯相对含量均高于9%，苯甲酸相对百分含量3个花期均差异显著（P<0.05）；油菜中乙偶姻、1-辛醇、1,3-二叔丁基苯和2,2,4-三甲基戊二醇异丁酯相对百分含量3个花期均差异显著（P<0.05）。3个花期中，砀山酥梨和甘蓝型油菜花共有的挥发性气味物质中乙偶姻相对含量差异均极显著（P<0.01）。相较于石蜡油，中蜂和意蜂触角对所测试的71种挥发性气味物质均产生电信号响应，其中中蜂对乙酸、丙酸、异戊醇、1-戊烯-3-醇和异己酸乙酯反应较强，意蜂对乙酸、丙酸、异丁酸、乙二醇单异丁醚和异己酸乙酯反应较强。中蜂和意蜂触角对其中22种挥发性气味物质的相对响应值差异显著（P<0.05）。EAG实验表明，中蜂对苯甲醇、邻苯二甲酸二异丁酯、2-羟基-3-甲基戊酸甲酯、辛酸、异戊醇、2-甲基丁醇、芳樟醇、十一烷、十二烷、十五烷和十六烷的相对响应值显著高于意蜂（P<0.05），对苯丙酸乙酯、茴香酸乙酯和1-戊烯-3-醇响应值极显著高于意蜂（P<0.01）；意蜂对1,3-二叔丁基苯、辛酸乙酯、乙偶姻、丙酸、己酸和二甲基二硫相对响应值显著高于中蜂（P<0.05），对异丁酸和乙二醇单异丁醚响应值极显著高于中蜂（P<0.01）。在Y型嗅觉仪实验中，中蜂对苯乙醇、苯甲酸甲酯、长叶环烯和芳樟醇的选择率显著高于对照组（P<0.05）；对二甲基三硫、乙酸的选择率显著低于对照组（P<0.05）。意蜂对苯甲酸甲酯、甲基庚烯酮、α-法尼烯、植酮、2-甲基丁酸乙酯和异戊醇的选择率显著高于对照组（P<0.05）；对二甲基二硫、乙偶姻、乙酸、2-甲基丁酸、1-辛烯-3-醇和辛醇的选择率显著低于对照组（P<0.05）。【结论】 梨花中释放的乙偶姻对蜜蜂有趋避作用，油菜花中释放的苯甲酸甲酯对蜜蜂有引诱作用，这可能是影响蜜蜂在梨花和油菜同花期时偏好采集油菜花的原因之一。

Abstract  [Aim]  To explore the differences in the types and contents of volatile compounds in pear and rapeseed flowers at the same flowering stage, and to identify the volatile compounds that influence bee host plant preference. The findings of this study will facilitate the development of inducers that can stimulate bees to pollinate pear trees, thereby providing a guide for the selective screening of bee species specialized for pear pollination. [Methods]  Headspace solid phase microextraction (SPME) and gas chromatograph-mass spectrometer (GC-MS) were used to analyze the volatile compounds in the flowers of Pyrus bretschneideri cv. Dangshansu and Brassica napus at different flowering stages. Using electroantennography (EAG) we isolated the volatile compounds from pear and rapeseed flowers that generated significant responses from Apis cerana and

A. mellifera ligustica. A Y-tube olfactometer was then used to verify the volatile compounds A. cerana cerana and A. mellifera ligustica showed significant foraging preferences towards. [Results]  A total of 52 volatile compounds were identified in the big bud stage, initial bloom stage, and full bloom stage of pear flower. A total of 61 of volatile compounds were identified from the three flowering stages of rapeseed flower. There were 12 shared volatile compounds in the three flowering stages of pear and rapeseed. In the three flowering stages of the pear, the relative content of acetoin and 1,3-di-tert-butylbenzene exceeded 9%. Additionally, the relative content of benzoic acid was significantly different between the three flowering stages (P<0.05). There were significant difference in the relative contents of acetoin, 1-octanol, 1,3-di-tert-butylbenzene, and kodaflex txib between the three flowering stages of rapeseed (P<0.05). An analysis of the common volatile compounds found in pear and rapeseed flowers at identical flowering stages showed there was a significant difference in the relative content of acetoin between the three flowering stages (P<0.01). Compared to paraffin oil, the antennae of A. cerana cerana and A. mellifera ligustica produced electrical signal responses to the 71 tested volatile compounds. Of these, A. cerana cerana exhibited the strong responses to acetic acid, propionic acid, 3-methyl-1-butanol, 1-penten-3-ol and pentanoic acid, 4-methyl-, ethyl ester, while A. mellifera ligustica showed strong responses to acetic acid, propionic acid, 2-methyl- propanoic acid, 2-isobutoxyethanol and pentanoic acid, 4-methyl-, ethyl ester. There was a significant difference in the relative response values of A. cerana cerana and A. mellifera ligustica antennae to 22 volatile compounds (P<0.05). EAG experiments showed that bees exhibited significantly higher response values to benzyl alcohol, diisobutyl phthalate, methyl 2-hydroxy-3-methylvalerate, octanoic acid, 3-methyl-1-butanol, 2-methylbutanol, linalool, undecane, dodecane, pentadecane, and hexadecane compared to

A. mellifera ligustica. Additionally, the response values of ethyl 3-phenylpropionateb, 4-methoxy ethylbenzoate and 1-penten-3-ol were also significantly higher than those of A. mellifera ligustica (P<0.01). The relative response values of

A. mellifera ligustica to 1,3-di-tert-butylbenzene, octanoic acid, ethyl ester, acetoin, propionic acid, hexanoic acid, and dimethyl disulfide were significantly higher than those of A. cerana cerana (P<0.05). Furthermore, the response values of

A. mellifera ligustica to 2-methyl-propanoic acid, 2-isobutoxyethanol were also significantly higher than those of A. cerana cerana (P<0.01). In the Y-shaped olfactometer experiment, the selection rates of phenethyl alcohol, methyl benzoate, longifolene, and linalool by A. cerana cerana were significantly higher compared to the control group (P<0.05). Additionally, the selection rate of dimethyl trisulfide and acetic acid was significantly lower than that of the control group (P<0.05). The selection rates of benzoic acid, methyl ester, 6-methyl-5-hepten-2-one, α-farnesene, 6,10,14-trimethyl-2- pentadecanone, ethyl-methylbutyrate, and 3-methyl-1-butanol in A. mellifera ligustica were significantly higher compared to the control group (P<0.05). Whereas, the selection rates of dimethyl disulfide, acetoin, acetic acid, 2-methyl-butanoic acid, 1-octene-3-ol, and 1-octanol were significantly lower than the control group (P<0.05). [Conclusion]  The acetoin released from pear flowers has a repelling effect on honeybees. In contrast, benzoic acid and methyl ester released from rapeseed flowers have an attractive effect on honeybees. This could be a key factor determining why bees display a preference for rapeseed flowers when pear and rapeseed flower simultaneously.