Repellent scent-marking of flowers by a guild of foraging bumblebees (Bombus spp.)

We have found that foraging bumblebees (Bombus hortorum, B. pascuorum, B. pratorum and B.␣terrestris) not only avoid flowers of Symphytum officinale that have recently been visited by conspecifics but also those that have been recently visited by heterospecifics. We propose that the decision whether to reject or accept a flower is influenced by a chemical odour that is left on the corolla by a forager, which temporarily repels subsequent foragers. Honeybees and carpenter bees have previously been shown to use similar repellent forage-marking scents. We found that flowers were repellent to other bumblebee foragers for approximately 20 min and also that after this time nectar levels in S. officinale flowers had largely replenished. Thus bumblebees could forage more efficiently by avoiding flowers with low rewards. Flowers to which extracts of tarsal components were applied were more often rejected by wild B. terrestris workers than flowers that had head extracts applied, which in turn were more often rejected than flowers that had body extracts applied. Extracts from four Bombus species were equally repellent to foragers. The sites of production of the repellent scent and its evolutionary origins are discussed. Received: 24 November 1997 / Accepted after revision: 8 March 1998     

恶臭物质的嗅觉阈值与致臭机理研究概况与展望

嗅阈值是表征气味物质特性的重要指标,对认识异味污染的形成机理、恶臭评估及污染控制有重要意义.围绕嗅阈值的测定方法、嗅阈值与分子结构的关系及复合臭气评估模型,论述国内外相关研究的概况,在指出现有研究不足的同时,提出有待解决的关键问题及重点研究内容.     

Choosing rewarding flowers; perceptual limitations and innate preferences influence decision making in bumblebees and honeybees

Flowers exhibit great intra-specific variation in the rewards they offer. At any one time, a significant proportion of flowers often contain little or no reward. Hence, foraging profitably for floral rewards is problematic and any ability to discriminate between flowers and avoid those that are less rewarding will confer great advantages. In this study, we examine discrimination by foraging bees among flowers of nasturtium, Tropaeolum majus. Bee visitors included carpenter bees, Xylocopa violacea, which were primary nectar robbers; honeybees, Apis mellifera, which either acted as secondary nectar robbers or gathered pollen legitimately and bumblebees, Bombus hortorum, which were the only bees able to gather nectar legitimately. Many flowers were damaged by phytophagous insects. Nectar volume was markedly lower in flowers with damaged petals (which were also likely to be older) and in flowers that had nectar-robbing holes. We test whether bees exhibit selectivity with regards to the individual flowers, which they approach and enter, and whether this selectivity enhances foraging efficiency. The flowers approached (within 2 cm) by A. mellifera and B. hortorum were non-random when compared to the floral population; both species selectively approached un-blemished flowers. They both approached more yellow flowers than would be expected by chance, presumably a reflection of innate colour preferences, for nectar standing crop did not vary according to flower colour. Bees were also more likely to accept (land on) un-blemished flowers. A. mellifera gathering nectar exhibited selectivity with regards to the presence of robbing holes, being more likely to land on robbed flowers (they are not able to feed on un-robbed flowers). That they frequently approached un-robbed flowers suggests that they are not able to detect robbing holes at long-range, so that foraging efficiency may be limited by visual acuity. Nevertheless, by using a combination of long-range and short-range selectivity, nectar-gathering A. mellifera and B. hortorum greatly increased the average reward from the flowers on which they landed (by 68% and 48%, respectively) compared to the average standing crop in the flower population. Overall, our results demonstrate that bees use obvious floral cues (colour and petal blemishes) at long-range, but can switch to using more subtle cues (robbing holes) at close range. They also make many mistakes and some cues used do not correlate with floral rewards.     

Molecular receptive ranges of olfactory receptor neurones responding selectively to terpenoids, aliphatic green leaf volatiles and aromatic compounds, in the strawberry blossom weevil Anthonomus rubi

Summary. An important question in insect-plant interactions is which of the numerous plant compounds contribute to the perception of odour qualities in herbivorous insects and are likely to be used as cues in host-searching behaviour. In order to identify which plant-produced volatiles the strawberry blossom weevil Anthonomus rubi detects, we have used electrophysiological recordings from single olfactory neurones linked to gas chromatography and mass spectrometry. We here present 15 receptor neurone types specialised for naturally produced compounds present in the host and nonhost plants and two types for two aggregation pheromone components. The active compounds were terpenoids, aromatic and aliphatic esters, alcohols and aldehydes, some of which are induced by feeding activity of the weevils. The neurones were characterised by a strong response to one or two primary odorants and weaker responses to a few others having similar chemical structure. With one exception, the molecular receptive range of each neurone type was within one chemical group. Enantiomers of linalool separated on a chiral column activated two neurone types with different enantioselectivity. Inhibition by linalool of another neurone type, excited by α-pinene, indicated an additional mechanism for coding the information about this compound. Altogether, detection of 54 compounds by olfactory receptor neurones is shown, of which 40 have been chemically identified in this study. Thus A. rubi has the ability to detect a large number of odorants that may be used in host selection behaviour.     

室内建筑装饰装修材料气味物质及其释放研究进展

室内建筑装饰装修材料释放的污染物可能导致气味,是消费者抱怨室内空气质量的主要原因.目前,针对室内建材气味污染物识别、定量及其释放规律的研究较少.本文总结了近年来室内气味物质的分析测定方法,梳理了已有研究中有关石膏、木质材料、油毡、地毯、塑料、橡胶、人造革、涂料和胶粘剂等9类建筑装饰装修材料释放的气味污染物的研究结果,列出了各类材料可能的致嗅物质及其嗅觉阈值,最后对加强室内气味污染研究和控制提出了建议.本研究发现,尽管不同建筑材料气味污染评价方法不统一,嗅觉测定法却是主要的评价方法.此外,虽然建筑材料释放的气味物质组成差异大,但建筑材料随时间老化和臭氧氧化时产生的气味物质主要为含氧基团的化合物,如醛、酮和酸等.     

硫醚类嗅味物质的检测和去除技术研究进展

硫醚类物质引起我国饮用水嗅味问题的典型嗅味物质。介绍了硫醚类物质的气味特征和产生来源;介绍了感官分析法、仪器分析法和感官气相色谱分析法3个主要的硫醚类物质检测技术的研究进展,简要阐述了各检测方法的优缺点和适用范围;论述了氧化技术、吸附技术、组合工艺对硫醚类物质的去除效果,阐明了去除技术适应情况及其主要问题。     

洞庭湖水体异味物质及其与藻类和水质的关系

以洞庭湖水体中异味物质为研究对象,开展异味物质调查,并结合藻类结构、水质及其营养状况等因素,深入分析洞庭湖异味物质的来源和变化情况. 结果表明,DMS(dimethylsulfide,甲硫醚)、DMTS(dimethyltrisulfide,二甲基三硫醚)、β-cyclocitral(β-环柠檬醛)、MIB(2-methylisoborneol,二甲基异冰片)和GSM(geosmin,土嗅素)在全湖广泛存在,其最高质量浓度分别达到500.80、28.80、21.84、14.50和22.40 ng/L. 结合与藻类生物量的相关分析发现,直链藻、冠盘藻等硅藻可能是洞庭湖中DMS、DMTS和β-cyclocitral的重要来源,湖区土壤、沉积物中的微生物和死亡分解的藻类是MIB和GSM主要来源. 洞庭湖水体绝大部分处于中营养水平,其中东洞庭湖TLI(综合营养状态指数,为48.3)最高,南洞庭湖(为47.3)其次,西洞庭湖(为42.7)最低. 异味物质含量和水质的相关分析发现,异味物质质量浓度与TLI、水温、pH、ρ(DO)、ρ(TN)和ρ(COD_Mn)显著相关,说明水质对异味物质含量有重要影响.      

上海市饮用水中痕量土臭素和二甲基异冰片年变化规律及来源研究

采用液液微萃取-气相色谱/质谱联用测定饮用水中痕量异嗅物质--土臭素(geosmin,GSM)和二甲基异冰片(2-Methylisoborneol,2-MIB或MIB).对上海市饮用水水源以及某水厂工艺出水进行调查发现,土霉昧的来源主要为2-MIB,异嗅问题暴发季节为7～10月,7、8月份达到顶峰,原水中2-MIB的最高检出浓度可达152.82 ng/L.水厂出水中最高检出浓度为97.94 ng/L.初步的来源分析推断2-MIB为水中颤藻的代谢产物.     

北京市安定生活垃圾填埋场VOCs恶臭物质及其臭气强度

挥发性有机物(VOCs)是填埋场重要的恶臭源之一.为了深入了解造成填埋场恶臭的VOCs及其臭气强度情况,在2014年7—8月采用固相微萃取(SPME)-气相色谱(GC)-质谱(MS)联用法测定了北京市安定生活垃圾卫生填埋场内各代表性地点的VOCs.共确认了48种化合物,包括烷烃、烯烃、芳香烃、环烷烃、萜类、酯类、醛酮类、卤代烃、醇类及含硫化合物和含氮化合物.烷烃的种类最多,达到13种,其次是芳香烃,为9种.以内标法和外标法相结合测定了其中35种物质的含量,发现浓度在0.05~40 mg·m~(-3)之间.在厂区入口和作业面浓度最高的VOC是2,2,4,6,6-五甲基庚烷,在沼气干管是甲苯.从实际经验和臭气强度出发,建立了一种恶臭物质筛选方法,即首先以检出频次和各地点浓度比值筛选出可能的恶臭物质,然后由臭气强度确定最终的恶臭物质.筛选结果表明,填埋场内的恶臭VOCs是对伞花烃、对二甲苯、乙苯、甲苯和邻二甲苯,其中对伞花烃和对二甲苯对恶臭贡献尤为显著.这些恶臭VOCs浓度之间呈现出显著的相关关系,表明这些物质均来源于填埋场内生活垃圾的降解过程.     

笼养肉鸡舍冬季挥发性有机物排放特征

畜禽养殖过程产生的挥发性有机物（VOCs）会影响周围环境质量和人畜健康.针对肉鸡养殖过程挥发性有机物排放特征研究较少,主要致臭物质及致癌、非致癌健康风险影响评价不明确、臭氧生成潜力分析不足等问题,开展了对肉鸡舍内挥发性有机物的现场监测试验,在肉鸡舍采用苏玛罐采样结合气相色谱-质谱法分析了冬季肉鸡生长前期、生长中期和生长后期VOCs的排放特征.结果表明,肉鸡生长过程中共检测出77种VOCs,包括16种卤代烃、21种烷烃、5种烯烃、12种芳香烃、15种含氧VOCs （OVOCs）和8种含硫化合物.整个生长阶段舍内卤代烃、烷烃、烯烃、芳香烃和OVOCs浓度变化不大,但是随着肉鸡的生长,含硫氨基酸摄入量和粪便排污系数增加,舍内排放的VOCs逐渐转为硫化物为主.含硫VOCs浓度在生长前期和中期呈现不断升高趋势,但是生长后期舍内通风量增加导致含硫VOCs浓度降低.肉鸡生长过程中监测到的VOCs中主要致臭物质为萘、乙酸乙酯、乙醛、二硫化碳、二甲基二硫、甲硫醇、甲硫醚和噻吩,其中甲硫醇的恶臭指数最高,范围为2172.4~19090.9;生长前期和生长中期存在可能致癌健康风险,终生癌症风险（LCR）值分别为7.7×10^-6和4.5×10^-6.舍内VOCs臭氧生成潜势（OFP）平均值为（1458.9±787.4）μg ·m^-3.结果明确了肉鸡生长过程中VOCs的排放特征,摸清了致臭物质、健康风险和臭氧生成潜势,可为肉鸡养殖过程中污染气体减排策略的制定提供科学依据.