Transmission of a pathogen in Bombus terrestris,with a note on division of labour in social insects

Summary Parasites of social insect workers can be transmitted within the colony to other, related host individuals or, alternatively, to unrelated workers of other colonies. Division of labour affects the probability of transmission, as young individuals often work inside the nest whereas older ones often leave the nest to forage. Therefore, the relative probabilities of transmission within-vs. between-nests is also affected by the delay between host infection and the shedding of propagules, i.e. the latent period of the parasite strain. We therefore hypothesized that strains of the flagellate parasite Crithidia bombi (Trypanosomatidae, Zoomastigophorea) infecting workers of the bumble bee Bombus terrestris (Hymenoptera, Apidae) could differ in their delays and coexist in a population. This would be the case if strains that are shed after a short time delay were more efficiently transmitted to other colony members, whereas strains with long delays were more efficiently transmitted to non-related workers in the population. We tested this hypothesis by experimentally varying time delay and by allowing transmission to either sister workers from the same nest or unrelated workers from other nests. Transmission of C. bombi was measured as the number of parasitic cells shed by the exposed workers after a standard period. The results showed that relatedness as such had no effect, but that delay and nest identity were highly significant effects to explain variation in transmission success. There was a significant interaction between nest identity and delay, such that bees of some colonies acted as efficient transmitters for C. bombi under short delays and vice versa. We discuss how division of labour may affect parasitism in social insects and, vice versa, how division of labour may be under selection from the effects of parasitism, using available evidence from the literature. Correspondence to: P. Schmid-Hempel     

Division of labour in a crisis: task allocation during colony emigration in the ant Leptothorax unifasciatus (Latr.)

Division of labour during colony emigration is widespread in ants. An important problem is how tasks are allocated during colony movement from one nest site to another. The generally favoured view is that emigrations are organised by a minority group of individuals, which either work unusually hard at tasks (elites) or have the exclusive task of carrying out the emigration (moving specialists). Five consecutive emigrations of a Leptothorax unifasciatus (Latr.) colony showed that the number of transporters, i.e. the individuals that took an active part in the emigration by transporting brood and ants, was smaller than it would have been if allocation of this task was random during each emigration. However, single emigrations of another three colonies, for which the spatial distribution and behaviour of the workers had been observed for a week prior to the emigration, demonstrated that the transporters did not form a homogeneous group. They differed in their spatial positions and tasks before the emigration. There was also no evidence that transporters worked harder or less hard than their nestmates before the emigration. Therefore, the individuals which carry out emigrations in L. unifasciatus colonies appear to be neither moving specialists nor elites. We propose that task allocation during emigrations of L. unifasciatus colonies is based on a feedback mechanism that involves learning.     

噪声功能区划中一类,二类混合区域的划定方法研究

根据灰色系统理论,通过灰色聚类的方法判定噪声功能区中的一类、二类混合区。判定结果与实际情况具有较高吻合度。     

浅谈沈阳市地表水环境功能区达标存在的问题及应采取的措施

对沈阳市地表水水质现状及实现功能区达标存在的问题及原因进行了分析 ,并就如何实现地表水环境功能区达标的阶段目标提出了相应的对策     

汉阳江阳江段水环境功能区划分研究

通过对汉阳江水环境现状的调查，结合阳江市城市发展规划，提出了水环境功能区划分的原则，科学而又切合实际的划分了汉阳江阳江段水质功能，对加强环境管理，保护河流水质具有十分重要的意义。     

五角场--江湾生态环境区规划构思

在对五角场－江湾规划小区的环境现状分析与评价的基础上，重点选取具代表性的环境质量、污染控制和环境建设３方面的参数，作为建设环境生态区的指标，提出了以２０１０年为远景目标的生态环境区规划构思。按规划设想，到２０１０年该区域综合环境质量，可望达到上海市进入现代化国际大都市的要求，成为上海东北角的新兴地区。     

模糊综合评判在港口船舶溢油风险区划中的应用

阐明港口船舶溢油风险区划的必要性，提出了应用模糊综合评判进行溢油风险区划的方法，给出算例并加以讨论。     

The role of public policy in advancement of product service systems

This article discusses developments in the area of product service systems (PSS) and the need to facilitate the proliferation of the PSS approach through public policies. The article argues that policies that establish the framework conditions for environmental improvement are preferable to detailed legislation as they favour environmentally superior PSS. However, there is also a need for more specifically targeted policy measures that stimulate knowledge creation and dissemination in the PSS area. This article suggests that informative policy measures should be used by authorities and reviews the results from the functional programme of the Swedish EPA as an example of this type of policy.     

长江经济带国家重点生态功能区生态补偿环境效率评价

环境效率是考量生态补偿政策实施效果的重要指标,对国家重点生态功能区生态补偿环境效率进行有效测度可以为完善我国生态补偿政策提供有益参考.采用三阶段DEA模型对长江经济带11个省市的国家重点生态功能区生态补偿环境效率水平、变化趋势及其差异性进行评价,通过线性数据转化方法对非期望环境负产出进行处理,并识别第三产业增加值占比等背景变量对投入产出效率的影响.结果表明:①长江经济带第三产业增加值占比对能源投入产出的影响显著（t值检验达到5%显著性水平）,进出口总额、人均GDP、人口密度等因素对各项投入产出的影响均不显著.②长江经济带11个省市2012-2017年综合技术效率均值在剔除背景因素和随机干扰前后未发生变化,但纯技术效率均值由调整前的0.94升至调整后的0.96,规模效率均值由调整前的0.94降至0.92,表明纯技术效率对提高环境效率起主导作用.③上游4个省市（重庆市、四川省、云南省、贵州省）与中下游7个省市（江西省、湖南省、湖北省、安徽省、江苏省、浙江省、上海市）生态补偿环境效率均值差距较大,其中,云南省的环境效率最低.研究显示,长江经济带11个省市的国家重点生态功能区生态补偿环境效率从上游到下游整体呈上升趋势,应在提高综合技术效率的同时,更加注重基本公共服务能力和生态环境保护双重目标的协调.      

秦皇岛市生态农业模式分析

本文根据秦皇岛市的地理条件,气候资源和土壤资源,分析了该地区的农业生产总环境和自然经济条件,提出了因地制宜,合理利用各地的自然资源,建立科学合理又相近相趋的生态农业模式和实施方案。