Larval chemical defence and evolution of host shifts in Chrysomela leaf beetles

Summary. Larvae of Chrysomela leaf beetles release for defence volatile compounds belonging to various chemical families. This study focuses on the defensive strategy based on the esterification of isobutyric acid and 2-methylbutyric acid with a wide variety of alcohols taken up from the host plant. To date, only two species are known to produce these repellents C. interrupta, which is associated with Betulaceae and C. lapponica which occurs either on Betulaceae or Salicaceae.? In order to know if other species have developed this chemical defence and how the food plant influences the secretion of these toxins, we targeted by mass spectrometry the presence of iso- and 2-methylbutyric acids and esters of them in the defensive secretions of Chrysomela larvae exclusively associated with Betulaceae or Salicaceae. ?Screening analyses reveal that the synthesis of these compounds is a common character restricted to all the members belonging to the C. interrupta group sensu Brown (1956) regardless of the host-plant family. These results suggest that the biochemical mechanism leading to the synthesis of these compounds could be considered as a synapomorphy meaning that the group is probably monophyletic. ?Defensive secretions of the members of the interrupta group are quantitatively assayed for iso- and 2-methylbutyric acids and their (Z)-3-hexenyl esters. Results reveal a chemical plasticity developed by Chrysomela species associated with Salicaceae. The amounts of iso- and 2-methylbutyric acids derivatives and of salicylaldehyde in their larval secretions depend on the food plant and on its content in phenolglucosides. Received 5 October 1998; accepted 25 November 1998.     

Spray mechanism of crepidogastrine bombardier beetles (Carabidae; Crepidogastrini)

Summary.   The defensive glandular apparatus of primitive bombardier beetles of the tribe Crepidogastrini (Carabidae) is described for the first time. As exemplified by two African species (Crepidogaster ambreana and C. atrata), the apparatus conforms to the basic bombardier plan, in that the glands are bicompartmented and the secretion is quinonoid (it contains 1,4-benzoquinones and hydrocarbons), hot, and discharged audibly. In a number of morphological respects the crepidogastrine apparatus resembles that of the classical bombardiers of the tribe Brachinini (rather than that of bombardiers of the paussoid lineage), reinforcing the view, already held on taxonomic grounds, that the Crepidogastrini and Brachinini are closely related. That the Crepidogastrini may be primitive relative to Brachinini is underscored by the finding that, unlike brachinines, crepidogastrines do not pulse their secretory emissions. Moreover, they discharge their secretion as a mist, rather than forcibly in the form of jets. Received 22 May 2001; accepted 29 May 2001.     

运用法律手段加强环境治理工作的有效性

单靠道德自律及经济、行政性处罚等手段 不可能从根本上解决环境问题，唯有加强法律作为硬性强制性手段，才能加大环保工作的有效性。     

水污染突发事件：演化模型与应急管理

概述了突发事件演化研究的现状，总结了现阶段中国水污染突发事件的典型案例，研究了事件的演化过程，提出把社会因素和全过程干预作为水污染突发事件演化动因的一个重要方面，并在此基础上分析了水污染突发事件演化的主要动力因素，运用灾害学、应急管理、环境科学等相关理论构建了事件演化的动力因素体系，最后从系统分析的角度构建了水污染突发事件演化模型。研究表明：社会因素和应急干预对水污染突发事件的演化具有推动作用；事件演化具有阶段性，不同阶段的动力因素存在差异；水污染突发事件应急管理具有多目标性，单一目标应急管理不能有效控制水污染突发事件演化。研究水污染突发事件演化机理可为政府有效地预警与事件初期的应急决策提供重要的理论依据。     

Volatilization characteristics of organic solutes in stirred solution

The effects of turbulence intensity (velocity gradient, G (s⁻¹)), Henry's law constant (H), and molecular weight (M) on the volatilization rates of organic compounds are examined using changes in the mass transfer coefficients (K_OL (cm/min)) under specific liquid-mixing intensities. The selected compounds were divided into three groups according to their H values (mole in gas/mole in liquid, dimensionless), which ranged from 10² to 10⁻⁵. The relationship of the K_OL relative to G, H and M was obtained via multiple regression. The obtained values of these parameters indicate that the primary factor affecting the K_OL values of the high H compounds is their M values. The effects of the H values on the K_OL values of the high H compounds can be neglected. On the other hand, the H value is the major factor determining the K_OL values of the low H compounds. The changes in the K_OL values of the different H compounds exhibit different profiles as the liquid-mixing intensity increases. The M and H values of middle H compounds possibly affect their K_OL values. The effects of the liquid-mixing intensity on the K_OL values of the organic compounds increase with increasing H values. The variation in the K_OL values might be a result of the concentration of the organic compounds at the interface between the liquid and gas films. The empirical relationship between K_OL and some selected parameters, G, H and M, is examined in this study. The obtained results can help to estimate volatilization loss of organic solutes in wastewater treatment facilities.     

Association of Coloration Mode with Population Declines and Endangerment in Australian Frogs

Abstract: Successful protection of biodiversity requires increased understanding of the ecological characteristics that predispose some species to endangerment. Theory posits that species with polymorphic or variable coloration should have larger distributions, use more diverse resources, and be less vulnerable to population declines and extinctions, compared with taxa that do not vary in color. We used information from literature on 194 species of Australian frogs to search for associations of coloration mode with ecological variables. In general, species with variable or polymorphic color patterns had larger ranges, used more habitats, were less prone to have a negative population trend, and were estimated as less vulnerable to extinction compared with nonvariable species. An association of variable coloration with lower endangerment was also evident when we controlled statistically for the effects of range size. Nonvariable coloration was not a strong predictor of endangerment, and information on several characteristics is needed to reliably identify and protect species that are prone to decline and may become threatened by extinction in the near future. Analyses based on phylogenetic‐independent contrasts did not support the hypothesis that evolutionary transitions between nonvariable and variable or polymorphic coloration have been accompanied by changes in the ecological variables we examined. Irrefutable demonstration of a role of color pattern variation in amphibian decline and in the dynamics and persistence of populations in general will require a manipulative experimental approach.     

三峡库区腹地规模农地空间分布规律

山区农业转型对于我国山区耕地可持续利用效率、土地整治方向以及生态建设方向具有一定的指导意义,渝东北生态涵养发展区是重庆市农用地整治项目的主要分区,通过定义作为农业转型产物的"规模农地"相关概念及其判读标准,旨在提出一种新的研究路径对重庆市典型山区地貌的耕地利用现状给予指导和改善意见。首先选取三峡库区腹地5个区县为研究区,并结合研究区实际对"规模农地"进行等级划分,利用Arc GIS10.2等软件通过景观格局指数、核密度测算、空间自相关等方法从斑块特征、数量分布、空间格局三方面对研究区内规模农地的空间分布规律进行探讨。研究表明:(1)不同类型规模农地斑块特征呈现一定的规律性,小规模农地斑块密度最大为6.004,大规模农地平均最近指数MNN值最低为643.401,且农地规模越大,面积加权平均斑块分维数AWMPFD值和聚集度AI值越高;(2)中、大规模农地数量多集中在奉节县,微、小规模则多集中在巫山县,且规模农地自身及其相互之间存在固定的邻接性规律,即同类斑块之间的邻接性与其斑块大小成反比,不同类型斑块之间则与之相反;(3)研究区规模农地整体空间分布主要集中在奉节县中部以及巫溪县东部,沿江流域的平坝地区分布相对密集,且不同类型规模农地在空间上存在明显的自相关性。     

下蜀土边坡地震稳定性的大型振动台试验研究(Ⅰ)——模型试验设计

为研究下蜀土边坡的地震稳定性,选用天然下蜀土,按照Meymand的相似法则,对一坡高为0.5m、宽度为1.05m、坡角为45°的模型边坡进行了几何相似常数为20的1g大型振动台模型试验详细设计。首先,运用数值模拟的方法确定了模型边坡尺寸适当的边界范围,模型边坡地基厚度、坡脚前缘和坡肩后缘长度均取为0.5m;其次,按照确定的模型几何尺寸设计了符合试验要求的模型箱,其内壁净尺寸(长×宽×高)为1500mm×1050mm×1100mm,属刚性模型箱,且不会与模型边坡发生共振;最后,制定了包括加速度和位移在内的数据量测策略,运用拟静力法求得下蜀土边坡平均屈服加速度为0.561g,综合确定了地震动峰值(PGA)按0.1g、0.3g、0.6g和0.9g的顺序逐级加载的原则,并制定了详细的试验步骤,从而可保障试验得到可靠的结果。     

浅谈深圳市环境监督管理全覆盖移动执法系统的建设和应用

环境监督管理全覆盖移动执法系统,是利用现代无线通信技术、计算机技术等先进技术手段,利用手持终端(PDA)、手提电脑等设备,通过无线数字通信网的支持,实现在任何执法地点都可从后台业务系统中获取所需的业务数据、文字、图片、视频等信息,同时将现场执法的信息及时回传至后台系统中。本文介绍了移动执法系统的建设以及应用的情况。     

西藏"一江两河"地区人口空间分布的动态演变

人口分布的空间演变是人口发展过程中在时间和空间上的表现形式,人口的集聚与扩散是诠释区域人口空间分布格局与形态的重要方面.对其研究有助于揭示人口分布现状的本质、理解区域空间结构特征及演变趋势.本研究运用局部空间自相关方法,并结合GIS技术,以县域为基本单元,人口密度为衡量指标,对西藏"一江两河"地区1990-2008年间人口分布空间格局的演变进行了分析.分析结果表明,"一江两河"地区各县市(区)人口总量和密度均有明显增长,人口分布总体上呈现出不断集中的态势.局部自相关分析揭示"一江两河"地区开始显现以拉萨市和日喀则市为中心的两个显著的人口高密度区,显示出该区域人口分布的多中心空间结构特征.对以拉萨市、日喀则市和乃东县为中心的区域密度函数进行拟合.多中心区域密度函数的估计结果显示,"一江两河"地区空间发展正逐步由20世纪90年代单中心(拉萨市城关区)阶段,向目前的多中心向心集聚阶段转变,除拉萨市城关区外,日喀则市和乃东县集聚能力开始显现.