环境湿度和降雨对昆虫的影响

气候因素与害虫的个体发育和种群动态密切相关.其中,环境湿度(包括空气相对湿度和土壤含水量)变化直接导致昆虫体内含水量变化,从而打破虫体内的水分平衡,进而对其个体发育及群体发生等产生影响.降雨在影响环境湿度的同时,其物理冲刷作用也影响着昆虫田间种群发生动态.因此,研究环境湿度和降雨对昆虫的影响很有意义.本文综述了环境湿度和降雨及其它环境因子(如温度等)的联合作用对昆虫的影响,介绍了其在影响昆虫生长发育、生存、行为、生殖和种群生态学方面的研究进展,并简要介绍了环境湿度调节(如灌溉等)在调控害虫(如棉铃虫)田问种群发生方面的应用.     

昆虫社会行为的进化与生态适应

一、引言昆虫社会行为的进化涉及两大问题:(1)社会行为的起源和进化过程;(2)社会行为的适应意义。这两个问题都曾使达尔文感到困惑。达尔文曾详尽地描述过蜜蜂复杂的造巢行     

植食性昆虫学习行为与害虫治理的关系

植食性昆虫的学习行为一般具有习惯性反应、厌恶性学习、联系性学习、敏感性反应、嗜好性诱导几种类型,它们对害虫防治方法的效果具有重要影响。害虫通过嗜好性诱导对栖境中大面积单作农作物造成更大的危害,通过联系性学习可对诱虫植物的效果产生积极或消极的影响。害虫对驱避剂或杀虫剂等产生习惯性反应可降低其防治效果。害虫对寄主植物驱避抗性产生习惯性学习就会加重对作物的为害,产生厌恶性学习则有利于对作物的保护。利用害虫的联系性学习行为,释放前让不育雄虫学习自然交配场所的环境刺激,可增强通过释放不育雄虫控制害虫的防治效果。了解植食性昆虫学习行为对害虫治理的影响有助于研究和发展有效的栖境调控、行为调控等策略和方法。     

蝎对干旱环境的适应进化

蝎类是荒漠环境中占优势的无脊椎动物捕食者,在长期的适应进化过程中,发展出了一系列适应性特征。从形态结构、生理学、生物学和行为学等几个方面初步阐述了荒漠蝎类对干旱环境的适应进化问题。     

植物干旱胁迫对植食性昆虫及其天敌的影响

全球正经历以变暖为主要特征的气候变化,由此带来的干旱将对农业生态系统造成重要影响。本文综述了干旱胁迫下寄主植物对植食性昆虫及其天敌影响的国内外最新研究进展。在干旱胁迫下,寄主植物物理性状、营养状况和次生代谢物质等均发生变化,这些变化导致植食性昆虫的生存环境和营养物质的获取等方面发生改变,从而影响了害虫生长发育和种群动态。干旱胁迫还导致寄主物候变化与昆虫发生不同步,使害虫缺乏食物。另外干旱也会引起植食性害虫天敌的种群发生变化,从而对植食性昆虫种群数量产生间接的影响。     

迁飞过程中昆虫的行为:对风温场的适应与选择

本文综述了昆虫在迁飞过程中对大气物理环境的各种行为反应,有边界层气象的理论重新审视迁飞种群的时空分布,提出了“边界层顶现象”的概念。即边界层顶的低空逆温和低空急流为迁飞种群提供了最适宜的风温场,迁飞种群在边界层顶集聚成层,并通过定向理一步修饰其位移方位,表现出对风温场的主动选择能力和对大气结构和运动的高度复杂的适应性反应。进一步深化对“边界层顶现象”的认识,对迁飞性害虫的异地预测具有重要的理论意义     

UV对昆虫的生物学效应及昆虫适应机制

紫外光（Ultraviolet light,UV）源于太阳辐射,是一种重要的环境因子,昆虫作为地球生态系统中的重要参与者其生命活动也会受到UV辐射的影响。UV辐射对昆虫造成的生物学效应除与波长、辐射强度等光学特性有关,还与其他非生物因素和生物因素有关。昆虫长期与UV共存,也进化出了行为适应、生理适应等各种抵御UV辐射的能力。本文从多方面综述了UV对昆虫的生物学效应,以及昆虫对UV胁迫的适应机制,有利于认识和理解昆虫应对物理胁迫的生理对策,为丰富和完善害虫物理防治策略提供科学依据,对促进害虫物理防治产业的发展具有重要意义。     

昆虫对植物次生性物质的适应策略

植物次生性物质是植食性昆虫在取食过程中遇到的主要障碍之一,也是天敌昆虫寻找寄主或猎物的主要信息来源。当今,昆虫学中的一些重要理论问题,如寄主植物的识别,食性的形成,植物求救信号的释放,天敌对寄主或猎物的识别和寻找机制等等,均与植物次生性物质有关。在长期的演化过程中,昆虫适应了植物次生性物质的种种不利作用,改变了这类物质对植物本身的防御作用,使其能充分地利用各分类阶元的植物次生性物质作为寻找寄主植物、昆虫寄主或猎物以及取食的信号。昆虫与植物次生性物质的这种关系是当今协同演化理论得以产生的主要依据之一。关于昆…     

各种属性森林对干旱胁迫的响应研究进展

全球气候变化的背景下,干旱事件的发生频率、强度和持续时间不断增加,增加了森林生态系统面临的风险,探讨森林对干旱胁迫响应的规律与特征是生态学领域研究的热点。以干旱的定量表达为切入点,总结和归纳了评估森林对干旱响应的常见指标、评估方法和应用案例,特别是梳理了各种属性(如林龄、冠层高度等)的森林对干旱胁迫响应的差异性。基于当前研究进展和问题,提出在未来研究中,亟待发展多尺度综合解析各种属性森林对干旱胁迫响应差异的驱动机制研究;各种属性森林生态系统稳态转换临界点的探测;森林对干旱的响应规律在森林管理和模型优化的实践应用。     

昆虫对环境低氧的适应:生理和分子机制研究进展

氧是机体进行新陈代谢和维持生存的必要因素。低氧环境在自然界普遍存在,也是许多重大疾病(如癌症)发生过程中基本的病理生理特征。生物包括昆虫在其生存和发育过程中经常面对低氧的挑战,它们发展出了各自的适应策略以求得生存和繁荣壮大。昆虫对于低氧环境适应包括在气管系统通气量、气体交换模式、体型大小和发育时间等生理机制上的改变。为揭示昆虫低氧适应机制,研究人员针对不同昆虫采用了来自人工选择或者自然选择的品系(种群),使用了基因芯片表达和转录组测序、基因组重测序技术和基因操作等技术。基于这些方法研究发现,在分子机制方面,昆虫可以通过抑制能量代谢、提高氧气利用率来适应低氧环境;还可以通过胰岛素通路、低氧诱导因子(HIF)信号通路等来调节自身代谢活动从而适应环境低氧;除此之外,昆虫的气管系统可以在基因调控下通过代偿性生理和形态变化来适应低氧环境。昆虫低氧适应机制的研究为探求昆虫数亿年进化过程中体形改变、物种形成、种群动态等提供提供新的视野,也增进对动物应对低氧或缺氧机理的深入理解,特别是为研究人类重大疾病的发生提供重要启示。     

入侵昆虫对全球气候变化的响应

生物入侵已成为一个影响深远的全球性问题,其对我国的生态系统、环境和社会经济的负面影响日益明显。全球气候变化对入侵昆虫有着深刻的影响,它正改变着一些昆虫本地种与入侵昆虫的组成、分布、种群动态和种间关系。本文分析了气候变化与生物入侵之间的互作关系,综述了全球气候变化因子(如温度、湿度及其它气候因子)对入侵昆虫生物学及生态学的影响,探讨了气候变化导致入侵昆虫定殖和传播的原因,并提出了气候变化下入侵昆虫的防治对策。     

Excessive rainfall leads to maize yield loss of a comparable magnitude to extreme drought in the United States

Increasing drought and extreme rainfall are major threats to maize production in the United States. However, compared to drought impact, the impact of excessive rainfall on crop yield remains unresolved. Here, we present observational evidence from crop yield and insurance data that excessive rainfall can reduce maize yield up to ?34% (?17 ± 3% on average) in the United States relative to the expected yield from the long‐term trend, comparable to the up to ?37% loss by extreme drought (?32 ± 2% on average) from 1981 to 2016. Drought consistently decreases maize yield due to water deficiency and concurrent heat, with greater yield loss for rainfed maize in wetter areas. Excessive rainfall can have either negative or positive impact on crop yield, and its sign varies regionally. Excessive rainfall decreases maize yield significantly in cooler areas in conjunction with poorly drained soils, and such yield loss gets exacerbated under the condition of high preseason soil water storage. Current process‐based crop models cannot capture the yield loss from excessive rainfall and overestimate yield under wet conditions. Our results highlight the need for improved understanding and modeling of the excessive rainfall impact on crop yield.     

中国遥感干旱指数时空特征及其对气候和地表覆盖变化的响应

干旱严重影响植被生长,威胁粮食安全,基于遥感计算的植被状态指数（Vegetation Condition Index,VCI）、温度状态指数（Temperature Condition Index,TCI）和植被健康指数（Vegetation Health Index,VHI）是常用的干旱指数,被广泛应用于干旱监测。为了探究近年来我国干旱特征及其对气候和地表覆盖变化的响应,分析了2003-2016年期间VCI、TCI和VHI的时空变化特征;采用最小二乘（OLS）和偏相关分析方法分析了这些指数对气候和地表覆盖变化的响应。基于上述干旱指数计算的干旱频率表明,中温带中部和南温带等地区干旱发生频率高,干旱指数变化趋势表明在2003-2016年期间中国大部分地区干旱缓解,但在中温带、南温带和高原气候区等局部地区干旱加剧;总体而言,干旱指数随着年平均温度的上升和年降水量的降低而减小,VHI与温度和降水量的相关性在不同气候区的一致性优于VCI和TCI;裸土的减少和植被的增加导致干旱指数增大,树木转变为低矮植被干旱指数降低。     

外生菌根对干旱胁迫的响应

从外生菌根真菌、外生菌根共生体以及外生菌根的间接作用等方面阐述外生菌根如何抵制干旱胁迫,并对未来我国外生菌根的研究提出了建议。干旱可以抑制外生菌根真菌的生长并降低其群落中真菌的多样性,干旱胁迫下外生菌根真菌子实体可以利用深度30cm以下的土壤水,子实体的表面积和体积比可作为筛选抗旱真菌的一个重要因子;在遭受干旱胁迫时,外生菌根共生体可以发生形态变化来应对干旱,同时增加了植株水分的吸收并改善了植物的光合作用、活性氧以及激素等相关代谢;外生菌根对植物生长的促进作用、增加土壤碳汇以及对其他根际微生物生长的促进作用等对宿主植物应对干旱胁迫有利。未来我国外生菌根研究应加强对干旱区优良菌-树组合的筛选工作,同时加大对乡土外生菌根真菌资源的调查力度,未来研究应重点向分子生物学领域推进。     

森林土壤微生物对干旱和氮沉降的响应

干旱和氮沉降深刻影响着人类世森林生态系统的生命活动与物质循环,进而影响全球碳平衡、并反馈作用于气候变化。土壤微生物驱动元素的生物地球化学循环和关键土壤生态过程,在气候变化生物学研究方面具有核心地位和全球重要性。本文综述了干旱和氮沉降对森林土壤细菌和菌根真菌的影响。提出未来应加强全球变化多因子交互作用对土壤微生物多样性、活性与生态功能的研究;建立野外长期定位站,强化亚热带森林生态系统与全球变化研究;注重土壤生物之间互作及网络研究;利用微生物大数据建立相关的机理模型等。从认识微生物多样性和群落组成对全球变化的响应与适应,逐步发展为调控利用微生物群落服务于森林的优化管理、生态资源的合理保护与可持续利用,为充分发挥微生物减缓全球气候变化的作用提供理论基础。     

Response of African humid tropical forests to recent rainfall anomalies

During the last decade, strong negative rainfall anomalies resulting from increased sea surface temperature in the tropical Atlantic have caused extensive droughts in rainforests of western Amazonia, exerting persistent effects on the forest canopy. In contrast, there have been no significant impacts on rainforests of West and Central Africa during the same period, despite large-scale droughts and rainfall anomalies during the same period. Using a combination of rainfall observations from meteorological stations from the Climate Research Unit (CRU; 1950–2009) and satellite observations of the Tropical Rainfall Measuring Mission (TRMM; 1998–2010), we show that West and Central Africa experienced strong negative water deficit (WD) anomalies over the last decade, particularly in 2005, 2006 and 2007. These anomalies were a continuation of an increasing drying trend in the region that started in the 1970s. We monitored the response of forests to extreme rainfall anomalies of the past decade by analysing the microwave scatterometer data from QuickSCAT (1999–2009) sensitive to variations in canopy water content and structure. Unlike in Amazonia, we found no significant impacts of extreme WD events on forests of Central Africa, suggesting potential adaptability of these forests to short-term severe droughts. Only forests near the savanna boundary in West Africa and in fragmented landscapes of the northern Congo Basin responded to extreme droughts with widespread canopy disturbance that lasted only during the period of WD. Time-series analyses of CRU and TRMM data show most regions in Central and West Africa experience seasonal or decadal extreme WDs (less than −600 mm). We hypothesize that the long-term historical extreme WDs with gradual drying trends in the 1970s have increased the adaptability of humid tropical forests in Africa to droughts.     

Hydro-climate and ecological behaviour of the drought of Amazonia in 2005

In 2005, southwestern Amazonia experienced the effects of an intense drought that affected life and biodiversity. Several major tributaries as well as parts of the main river itself contained only a fraction of their normal volumes of water, and lakes were drying up. The consequences for local people, animals and the forest itself are impossible to estimate now, but they are likely to be serious. The analyses indicate that the drought was manifested as weak peak river season during autumn to winter as a consequence of a weak summertime season in southwestern Amazonia; the winter season was also accompanied by rainfall that sometimes reached 25% of the climatic value, being anomalously warm and dry and helping in the propagation of fires. Analyses of climatic and hydrological records in Amazonia suggest a broad consensus that the 2005 drought was linked not to El Niño as with most previous droughts in the Amazon, but to warming sea surface temperatures in the tropical North Atlantic Ocean.     

The impacts of increasing drought on forest dynamics,structure, and biodiversity in the United States

We synthesize insights from current understanding of drought impacts at stand‐to‐biogeographic scales, including management options, and we identify challenges to be addressed with new research. Large stand‐level shifts underway in western forests already are showing the importance of interactions involving drought, insects, and fire. Diebacks, changes in composition and structure, and shifting range limits are widely observed. In the eastern US, the effects of increasing drought are becoming better understood at the level of individual trees, but this knowledge cannot yet be confidently translated to predictions of changing structure and diversity of forest stands. While eastern forests have not experienced the types of changes seen in western forests in recent decades, they too are vulnerable to drought and could experience significant changes with increased severity, frequency, or duration in drought. Throughout the continental United States, the combination of projected large climate‐induced shifts in suitable habitat from modeling studies and limited potential for the rapid migration of tree populations suggests that changing tree and forest biogeography could substantially lag habitat shifts already underway. Forest management practices can partially ameliorate drought impacts through reductions in stand density, selection of drought‐tolerant species and genotypes, artificial regeneration, and the development of multistructured stands. However, silvicultural treatments also could exacerbate drought impacts unless implemented with careful attention to site and stand characteristics. Gaps in our understanding should motivate new research on the effects of interactions involving climate and other species at the stand scale and how interactions and multiple responses are represented in models. This assessment indicates that, without a stronger empirical basis for drought impacts at the stand scale, more complex models may provide limited guidance.     

Leaf hydraulic vulnerability to drought is linked to site water availability across a broad range of species and climates

Background and Aims

Vulnerability of the leaf hydraulic pathway to water-stress-induced dysfunction is a key component of drought tolerance in plants and may be important in defining species'' climatic range. However, the generality of the association between leaf hydraulic vulnerability and climate across species and sites remains to be tested.

Methods

Leaf hydraulic vulnerability to drought (P50_leaf, the water potential inducing 50 % loss in hydraulic function) was measured in a diverse group of 92 woody, mostly evergreen angiosperms from sites across a wide range of habitats. These new data together with some previously published were tested against key climate indices related to water availability. Differences in within-site variability in P50_leaf between sites were also examined.

Key Results

Values of hydraulic vulnerability to drought in leaves decreased strongly (i.e. became more negative) with decreasing annual rainfall and increasing aridity across sites. The standard deviation in P50_leaf values recorded within each site was positively correlated with increasing aridity. P50_leaf was also a good indicator of the climatic envelope across each species'' distributional range as well as their dry-end distributional limits within Australia, although this relationship was not consistently detectable within sites.

Conclusions

The findings indicate that species sorting processes have influenced distributional patterns of P50_leaf across the rainfall spectrum, but alternative strategies for dealing with water deficit exist within sites. The strong link to aridity suggests leaf hydraulic vulnerability may influence plant distributions under future climates.     

高寒植物叶片性状对模拟降水变化的响应

降水变化对高寒草甸生态系统产生了显著影响,植物叶片性状特别是叶脉特征对降水变化非常敏感,然而高寒植物叶片性状特征如何响应降水变化还知之较少。采用集雨棚模拟增减50%降水的条件,以高寒草甸8种主要植物叶片为研究对象,研究了降水变化对叶片的叶脉率、叶脉密度、叶片大小、比叶质量、叶片总有机碳含量、叶片全氮含量、叶片碳同位素相对含量和碳氮比等叶片性状的影响。发现增水显著增加了植物的叶片大小、稳定碳同位素千分值、总有机碳含量、全氮含量,但显著降低了叶脉密度;而减水显著降低了叶片大小、稳定碳同位素千分值。植物叶片性状各指标对降水变化的响应存在协同变化和相互制约。不同水分生态类型的植物对降水变化的响应存在差异,中生植物通过增加叶片大小和减少叶脉密度积极应对降水的增加,矮生嵩草的叶片大小分别增加了200.3%,叶脉密度减小了17.5%,而旱中生植物通过减少叶片大小和增加叶脉密度应对降水的减少,垂穗披碱草和异针茅的叶片大小分别减少54.9%和30.7%,其叶脉密度分别增加25%和22.4%。羽状叶脉植物增加叶脉密度和稳定碳同位素千分值以适应增水条件,花苜蓿、异叶米口袋的叶脉密度的增加了7.8%和4.0%,稳定碳同位素千分值增加2.5%和3.3%,但增水条件下平行叶脉植物的叶脉密度不变或降低和稳定碳同位素千分值保持不变;减水增加了平行叶脉植物叶脉密度并减低了稳定碳同位素千分值,异针茅的叶脉密度增加了22.4%,稳定碳同位素千分值减小2.9%,而对羽状叶脉植物的叶脉密度和稳定碳同位素千分值减少或不变。植物叶片性状对增水的敏感性显著大于对减水的敏感性,增水的效应约为减水的2倍;叶片大小的敏感性显著大于其它叶片性状,约为其它叶片性状的10倍。因此,植物在应对短期降水变化时,植物形态可塑性的作用凸显,放大或缩小叶片大小是植物应对降水变化的最有效的途径,但是不同水分生态类型和叶脉类型植物可塑性的方向存在显著差异。