Defence effectiveness of easy bleeding sawfly larvae towards invertebrate and avian predators

Summary. Easy bleeding is a phenomenon discovered in some tenthredinid insects which possess a particularly low mechanical resistance of the integument, leading under mechanical stress to haemolymph exudation. It has a defensive effect against ants and wasps through harmful plant compounds which are sequestered in the haemolymph. Here we describe etho-ecological and some chemical aspects of the defence of easy bleeders and specify the range of predators to which easy bleeding might be effective. Beside a high haemolymph deterrence associated with low integument resistance across sawfly species, we also detected toxicity of the haemolymph of some species to workers of the ant Myrmica rubra. The behaviour of easy bleeders is to move slowly and, once disturbed, to become motionless, thereby probably impeding the tendency of a predator to attack. This behaviour had no beneficial effect for easy bleeders when attacked by the predatory bug Podisus maculiventris. Bugs could successfully and without harm prey on sawfly larvae without evoking easy bleeding. For the easy bleeder Athalia rosae, host plants with different secondary metabolite profiles, and, consequently, changes in haemolymph chemistry only slightly affected the feeding behaviour of the bugs. To test the effectiveness of easy bleeding towards a vertebrate predator, easy bleeders were offered to birds, Sturnus vulgaris. The body colouration of the sawfly larvae was of prime importance in determining the predators response when testing birds in a group. It is likely that easy bleeding is a defence strategy directed primarily towards foraging insects with biting-chewing mandibles and that it is much less active towards predatory insects with piercing-sucking mandibles as well as birds. The involvement of chemical and/or physical cues in the strategy is discussed with respect to these types of predators.     

试论投资项目环境评价的理论基础

对投资项目进行环境影响评价是人类社会发展的必然产物,是人类实现可持续发展的必然要求,是有效解决人类生态困境的根本性环节之一.目前对投资项目的环境影响评价明显不足,现阶段,应加强其理论基础的研究.以可持续发展为目标对环境生态学、环境经济学和环境系统科学等相关理论进行深入的研究,并采取相应措施是进行有效环境影响评价的重要保证.     

产业生态学与生态产业建设战略研究

介绍了产业生态学的特征和基本原则,提出了生态产业的概念、特点及其建设战略。     

黄河三角洲地区总体开发战略研究

本文通过对黄河三角洲地区资源与经济状况的调查分析，从区域整体及其外部环境相互关系角度分析了黄河三角洲地区的战略地位、战略优势与问题、战略方向和战略措施，试图从理论和实践上为本区大规模开发建设提供科学依据。     

我国草原鼠害问题的生态学审视

对我国草原鼠害问题及其防治工作进行了回顾，并从草原生态系统角度分析了我国草原鼠害的成灾原因和成灾规律，据此提出了控制我国草原鼠害的战略措施。根据我国草原鼠害的特点，本文提出的控制战略是：（１）树产草地生态系统的整体效益观，即注重草地畜牧业发展中的生态效益、经济效益和社会效益“三统一”的原则和要求，造成鼠类不适宜的生存环境，促进草地生态系统的良性循环；（２）坚持连续多年的长期鼠情监测，搞好预测预报，     

Farmers’ risk preference and the adoption of risk management strategies in Northern Ghana

The study used the hypothetical lottery-choice questions to measure risk aversion and a detailed survey collected data on input use, farm production and non-farm activities to specifically assess whether risk aversion, risk perceptions, and socioeconomic factors affect the risk management strategies of farm households in Northern Ghana. Risk aversion significantly increases crop diversification strategies of households but marginally reduces herbicide use by households. Market risk significantly increases the use of improved seed varieties and the application of inorganic fertiliser but reduces diversification into livestock production. Production risk largely increases diversification into livestock production. Farmers’ risk management strategies are affected by socioeconomic variables such as access to extension services, area cultivated, age and gender. Policy effort focused on building pliable on-farm crop related risk management strategies should aim at considering the risk aversion and the perception of market risk whilst those focused on livestock should focus on production risk.     

华阳河湖群沉积物内源磷释放风险及控制策略

为研究沉积物内源磷释放对浅水湖泊水体总磷的影响,以华阳河湖群为对象,根据不同季节全湖水质监测数据,分析总磷的空间和季节性分布特征;结合沉积物间隙水磷浓度数据,采用浓度梯度扩散模型估算湖泊沉积物内源磷静态释放量;基于2019年在线水质监测站连续数据,分析典型沉积物再悬浮过程内源磷释放对水体总磷贡献及估算其年累积释放量.结果表明:①华阳河湖群现场监测总磷浓度变化范围为0.014~0.297 mg/L,龙感湖与黄大湖总磷浓度空间变幅大于泊湖;②典型再悬浮过程中内源磷动态释放对水体总磷的贡献可达75%,华阳河湖群内源磷的年释放量在1.129×104~1.684×104 t之间;③静态的内源磷年释放量为12.92 t,仅占动态释放量0.1%.研究显示:华阳河湖群总磷浓度时空差异较大,内源磷释放对总磷短期波动具有重要作用,静态释放量对全年内源磷释放量的贡献几乎可以忽略;严格控制入湖营养盐通量的同时,恢复草型湖泊生态系统以控制内源释放已成为解决华阳河湖群水环境问题的重要管理决策方向.      

居住建筑节能设计中的问题与优化策略研究

今天,全球能源在日益减少,人们生活提高又需要增加居住面积,这势必造成能源的消耗.因此,建筑节能已经成为全球范围内都非常关注的一项问题.为了提高居住建筑节能,结合实际需要,针对居住建筑节能的必要性的设计要求展开阐述,同时从规划节能设计、单体节能设计以及节能构造设计这三个不同的角度来着手分析,以期能够在有限的条件下将居住建筑的环保性、功能性以及艺术性更加完美的结合到一起,促进低成本、高效率的节能型居住建筑建设目标早日实现.     

电光源产品升级研究

本文罗列了近年来电光源产品的一些重要技术壁垒，并对这些壁垒进行了统计和分析，提出我国生产企业只有引进先进理念，变“被动应付”为“主动抵御”，才能实现电光源产品升级的观点。文章从四个方面详细阐述了技术壁垒的应对措施和产品升级设计的理念，希望对电光源生产企业提高产品质量有一定的启发。     

Reduction of Tobacco Smoking Health Risk Through an Appropriate Media Based Communication Strategy in Uganda

The health impacts of tobacco consumption are well documented and have gained acceptance worldwide. Today, a substantial, preventable burden of tobacco attributable diseases exists in most countries, though in most of the cases, unknown. Smoking accounts for almost half of the deaths in middle age in some regions. In Uganda, translating findings into policy action is slow and involves several stakeholders. It will continue to require support from tobacco control campaign groups. This paper analyses secondar...