Labial gland marking secretion in males of two Scandinavian cuckoo bumblebee species (genusPsithyrus)

Summary Chemical components of the cephalic labial gland secretion, which most likely is used as a precopulatory attracting signal, were identified in males of the cuckoo bumblebeesPsithyrus vestalis (Geoffroy) andP. bohemicus (Seidl.) by gas chromatography-mass spectrometry (GC-MS). The former species has geranylcitronellyl acetate as main component, plus in decreasing amounts geranylcitronellol, an eicosadienal, an eicosenol, and an eicosenal. Another 17 fatty acid derivatives are present in minor amounts. The labial secretion ofP. vestalis differs distinctly in its chemistry from that of all of the 8 other ScandinavianPsithyrus species. In the taxonomically closely related (same subgenus)P. bohemicus, the labial gland secretion contains 16 fatty acid derivatives, of which 12 (75%) are present also in the secretion ofP. vestalis. Thus, both the labial gland secretions, and morphological traits lend support to the hypothesis that the two species share a common ancestor. The reproductive isolation between them is, at least in part, supported by the inclusion of a second biosynthetical pathway (the mevalonic acid pathway producing terpenoids) inP. vestalis, in addition to the pathway common to both species (the polyketide pathway producing fatty acid derivatives).     

Sex pheromones and attractants in the Eucosmini and Grapholitini (Lepidoptera,Tortricidae)

Summary The geometric isomers (E,E)-, (E,Z)-, (Z,E)-, and (Z,Z)-8,10-dodecadien-1-yl acetate were identified as sex pheromone components or sex attractants in the tribes Eucosmini and Grapholitini of the tortricid subfamily Olethreutinae. Species belonging to the more ancestral Tortricinae were not attracted. Each one isomer was behaviourally active in males ofCydia andGrapholita (Grapholitini), either as main pheromone compound, attraction synergist or attraction inhibitor. Their reciprocal attractive/antagonistic activity in a number of species enables specific communication with these four compounds.Pammene, as well as otherGrapholita andCydia responded to the monoenic 8- or 10-dodecen-1-yl acetates. Of the tribes Olethreutini and Eucosmini,Hedya, Epiblema, Eucosma, andNotocelia trimaculana were also attracted to 8,10-dodecadien-1-yl acetates, but several otherNotocelia to 10,12-tetradecadien-1-yl acetates. The female sex pheromones ofC. fagiglandana, C. pyrivora, C. splendana, Epiblema foenella andNotocelia roborana were identified. (E,E)- and (E,Z)-8,10-dodecadien-1-yl acetate are producedvia a commonE9 desaturation pathway inC. splendana. CallingC. nigricana andC. fagiglandana females are attracted to wingfanning males.     

放牧生态系统与尺度问题

引言 最近20年,以前许多关于非洲放牧生态系统的假设都已经被抛弃了[1～4].例如,过去一直被认为是稳定的系统,由于过度饲养和放牧而变得不再稳定了.因此,根据Hardn的著名"公共灾难"概念[5]提出了新的管理方案,并集中于改变土地使用体制与降低饲养数量相结合.但不幸的是,根据这种理念确定的放牧管理项目,几乎没有取得什么成功.     

瑞典梅拉伦湖支流中的磷:分析馏分、人为贡献率及生物利用率

关于河流磷(P)浓度以及向瑞典第三大湖梅拉伦湖的磷输送量,现已在12条大支流中进行了为时35年的监测.在15个月时间内,对颗粒磷、悬浮物以及溶解活性磷进行了补充评价.按照水流加权平均数.颗拉磷占64%,溶解非活性磷占23%,溶解活性磷占13%,而且冬节性变化很大.对河流中的"背景"或"基准"磷输送量采用不同方法进行了估算,而人为对磷输送量的贡献呈现出随着时间推移而减少的趋势.对于排了水的耕地和森林覆盖地来说,藻类对颗粒磷的潜应利用率平均约为45%,而污水排放颗粒磷和藻类磷的利用率则较高.支流中的计算生物可利用总磷显示出与粗过滤水上测得的活性磷细等,同时有迹象表明在人为磷贡献率高的时期生物可利用磷的比例要比人为磷贡献率低的时期高.     

瑞典南部一酸性地区和一碱性地区女性头发中微量元素浓度问题

通过对瑞典南部一个酸性环境地区47名女性头发中34种微量元素浓度的测定,将其结果与某碱性环境地区43名女性的结果进行对比.利用感应耦合等离子光学发射光谱和感应耦合等离子质谱分析法测定头发和饮用水中这些元素的浓度.来自酸性地区的头发样本中硼和钡的浓度明显要高些(p＜0.001),而碱性地区头发样本中的钙、锶、钼、铁、硒浓度明显增高(p＜0.001).对有些金属元素,如钙、铅、钼和锶来说,其在头发中和水中的浓度是呈正相关的(r.=0.34～0.57;p≤0.001),显示了摄入水中矿物质的重要性.取自碱性地区头发样本中的硒/汞比率的增加(p＜0.001)说明这些受试者可能对汞的毒性有更好的防护.     

Sex allocation in Savi’s warblers <Emphasis Type="Italic">Locustella luscinioides</Emphasis>: multiple factors affect seasonal trends in brood sex ratios

Sex allocation theory predicts that whenever the relative fitness of sons and daughters differ, females should invest more in the sex with the greatest fitness return. In this study, we evaluated the influence of various ecological factors on the brood sex ratio (BSR) of Savi’s warblers (Locustella luscinioides) across several breeding seasons. There was a slight but significant female production bias at the population level, which is consistent with the ‘local resource competition’ hypothesis, as the breeding density is very high and females are more prone to disperse. We found that there was a significant decline in BSR during the breeding season, but no influence of male size, female size, social status nor extra-pair paternity were detected. The seasonal decline in BSR was further evaluated by assessing the within- and between-female effects, which indicated that multiple factors were operating simultaneously in our study population. First, there was a significant within-female decline in BSR, which was consistent with the decline in female condition due to the reproductive effort associated with multiple brooding (supporting the Trivers and Willard hypothesis). Second, a significant decline in BSR with the laying date of first clutches of different pairs indicated that male and/or female qualities are also associated with the seasonal variation in BSR. Finally, a comparison between the sex of the youngest nestling with the remaining ones did not suggest any bias, indicating that females do not compensate for the increased mortality of the last nestling (caused by asynchronous hatching) by producing a male from the last laid egg.     

Fuels for Transportation

There is a need to reduce the amount of fossil energy used for transport, both because of the easily available fossil fuel is becoming sparser and because of climate concerns. In this article, the concept of “peak oil” is briefly presented. Second, a practical approach to reduction of fossil fuel use for transport elaborated by two British commissions is presented. A key feature is the introduction of electric cars. This raises the third issue covered in this article: namely, how battery technology is going to meet the increasing needs posed by the transport sector.     

Women and community water supply programmes: An analysis from a socio-cultural perspective

Community water supply programmes are seen as instrumental in achieving the goal of ‘safe’ water for all. Women, a principal target group of these programmes, are to be benefited with greater convenience, enhanced socio‐cultural opportunities and better health for themselves and their families, provided through improved water facilities. Water supply programmes largely consist of three essential components, namely: technology, people and institutions. Although such programmes are intended to benefit women members of local communities, scant attention is paid to the impacts of the socio‐cultural context of the community on these programmes. This article explores the influence of social and cultural intricacies on the implementation of community water supply programmes, and assesses their effectiveness. The article offers important lessons for the design and implementation of this type of programme. It concludes that the local socio‐cultural context sets the stage for programme implementation, being a dynamic factor that determines actual access to water sources, more so than mere physical availability, which is often used as a criterion for programme performance. The article stresses the urgent need to integrate socio‐cultural factors as a fourth dimension in designing community water supply programmes, and suggests practical measures for enhancing the effectiveness of such programmes.