昆虫体色多型的分子调控机制

体色多型普遍存在于各昆虫类群,体色多型不仅是生物多样性的体现,而且多样的着色模式对于昆虫本身具有重要的生物学意义.研究体色多型对探讨昆虫遗传多态性、适应机制及生物进化等具有重要的意义.本文主要从昆虫体色多型的分子调控机制进行综述,以期为今后探讨昆虫多态性、适应机制及生物进化提供参考.     

甘薯天蛾幼虫体色分化动态的数值化评价指标及其应用

为解决无法用文字实现对近千种连续变化的昆虫体色进行准确的描述和合理的数学运算问题, 本文采用国际标准颜色计量技术-PFG (Pantone Formula Guide) 颜色指南为昆虫体色性状判别标准, 提出了关于数值化描述昆虫体色的相关评价指标, 如体色元 (body-color element, BCE) 、 体色群 (body-color group, BCG) 、 体色位 (body-color position, BCP)、 高频色码指数 (high frequency color-code index, HFI) 和杂色指数 (variegated color index, VCI) 等及其定量分析方法。并应用这些指标和方法, 研究了甘薯天蛾Agrius convolvuli幼虫个体在相似环境条件下体色分化的多样性以及不同发育日龄和不同虫体部位（体位）其体色的演化过程及其数值规律, 发现甘薯天蛾幼虫存在着共同的主体色, 而且其体色的变异主要发生在个体的不同发育日龄（占总变异的72.66%）, 其次, 虫体不同部位的颜色也有明显的差异（占总变异的24.45%）, 而同一发育日龄个体间的体色差异仅占总变异的2.88%。 结果说明, 甘薯天蛾幼虫体色随其发育日龄所发生的变化过程, 可能是由遗传因子所决定的一种生命体从发育到衰老的表观呈现过程。     

社会性昆虫级型和行为分化机制研究进展

社会性的出现是生物演化过程中的重要革新, 理解社会性的演化和调控机制具有重要的理论和实际意义。社会性昆虫的个体间有着明显的级型分化和劳动分工, 这有利于它们适应复杂的环境变化。理解社会性昆虫如何产生不同的形态、行为和生活史特性, 一直是进化和发育生物学的重要目标。随着测序技术的不断更新及生物信息学的快速发展, 已经有众多关于社会性昆虫级型和行为分化机制的研究报道。本文通过整理社会性昆虫研究的已有成果, 从环境因素、生理调控和分子机制等方面对社会性昆虫级型和行为分化机制相关研究进展进行了综述, 并对未来的研究方向做出了展望。根据现有证据, 社会性昆虫所生活的生物环境(食物营养、信息素、表皮碳氢化合物)和非生物环境(温度、气候等)均能直接或间接影响社会性昆虫级型和行为的分化; 保幼激素、蜕皮激素、类胰岛素及生物胺等内分泌激素和神经激素对社会性昆虫的级型和行为分化也有重要的调控作用; 此外, 遗传因素、新基因等DNA序列或基因组结构上的变化以及表观遗传修饰、基因的差异表达等基因调控机制均能不同程度地影响社会性昆虫的行为分化。本文建议加强昆虫纲其他社会性类群如半翅目蚜虫和缨翅目蓟马等的社会性行为及其演化机制的研究, 以加深对社会性昆虫起源及其行为演化的理解和认识。     

昆虫着色及体表黑色斑纹和斑点形成机制研究进展

昆虫在生长发育的过程中,会不断受到捕食者的攻击,为逃避被捕食在长期的适应进化中展现出各种适应性的形态特征,体色和斑纹的适应性变化是其中重要的防御策略。昆虫多样的着色模式常用于释放警告信号或者模仿宿主植物,避免被其他动物捕食并且加速逃避学习,而且在寻求伴侣、适应地理、调节体温和抵抗紫外线等方面发挥重要的生物功能,是昆虫学研究的热点之一。鳞翅目昆虫具有分布广、种类多的特点,大量的斑点和斑纹模式常见于鳞翅目昆虫中,其生物学功能比其他动物更明显。近年来研究发现色素色和结构色是昆虫主要的着色模式,眼色素、黑色素以及喋啶类色素是影响昆虫着色最重要的色素;而昆虫的寄主、环境因素、激素显著影响昆虫多样性着色模式的形成。利用定位克隆、经典遗传连锁图谱、RNA干涉、基因组编辑、高通量测序等技术分离鉴定出了多个调控鳞翅目昆虫着色的关键基因。研究表明, TH, DDC, yellow, laccase2, ebony, AA-NAT, tan和GTPCHI是昆虫色素合成信号通路中的关键基因,而多效性基因spz3, apt-like和wnt1以及20E诱导的转录因子E75A和spalt通过影响鳞翅目昆虫黑色素合成信号通路的活性从而调控黑色素的合成与沉积。本文对昆虫体色和斑纹多样性的形成和影响因素,昆虫着色类型及物质基础,以及黑色斑点和斑纹形成和调节机制方面的研究进展作了整理和总结,以期为今后着色基因的利用以及害虫防治提供理论参考。     

社会性昆虫品级分化的基因调控

品级分化是社会性昆虫的主要特征之一,包括雌性分化为生殖个体和非生殖个体,这一分化过程是受基因调控的。目前对社会性昆虫品级分化相关基因表达研究的报道较多,但是对这一分化的调控机制并不十分清楚,对这些基因的来源还存在争议。文章对社会性昆虫品级分化相关基因的研究概况作一综述,以期对以后相关方面的深入研究有所帮助。     

昆虫microRNA的研究进展

MicroRNA (miRNA)是20世纪90年代发现的一类由内源基因编码的长度约21~24 nt的非编码单链RNA分子, 广泛存在于真核生物中, 对基因的转录后调控起着非常重要的作用。本文简要介绍了miRNA的产生与调控机制, 同时从昆虫miRNA的发现鉴定、 靶基因预测与功能验证, 昆虫miRNA的序列特征与进化, 果蝇和非果蝇类昆虫miRNA生物学功能以及供昆虫miRNA研究的网络平台等方面对昆虫miRNA的最新进展进行了综述, 旨在为进一步研究昆虫miRNA提供借鉴和参考。对昆虫miRNA的研究表明其参与调控细胞分化、 增殖及凋亡、 胚胎发育、 器官发生、 形态构建、 生理代谢、 环境协调、 行为认知、 免疫防御等几乎所有的生物过程。因此, 深入研究其生物功能、 调控网络和开发应用等可能成为今后一段时间昆虫miRNA研究的重要内容。     

昆虫的黑化机理

昆虫的黑化是昆虫出现的一种体色变异。文章介绍工业污染、激素和温度等对昆虫黑化的影响、昆虫色素形成中多巴、多巴胺、N-β丙酰多巴胺(NBAD)和N-乙酰多巴胺(NADA)等色素前体的代谢、昆虫的黑化突变以及昆虫黑化的遗传。     

从形态学不同到基因水平差异: 家蚕与果蝇早期胚胎发育比较

昆虫的分化多样性一直是研究的一个热点, 对家蚕胚胎发育调控机制的研究将有助于加深人们对其他昆虫早期胚胎发育机制的了解。文章综述了鳞翅目昆虫家蚕和双翅目昆虫果蝇的早期胚胎发育在形态学及基因水平的研究结果。通过比较, 发现二者的早期胚胎发育存在较大差异。这一结果不但可以为家蚕胚胎发育调控机制的分子水平研究提供重要参考, 也可为昆虫分化多样性的分子机制研究提供线索。     

COⅡ基因在昆虫分子系统学研究中的作用和地位

细胞色素氧化酶Ⅱ(cytochromeoxidaseⅡ,COⅡ)基因位于线粒体DNA(mtDNA)上,编码细胞色素氧化酶亚基Ⅱ,该亚基为细胞色素c提供重要的结合位点。COⅡ基因进化速率较快,是昆虫分子系统学研究中理想的分子标记。目前,已经利用该基因从各个分类水平对昆虫系统发育关系、物种形成与分化、种群遗传与变异及生物地理等方面做了广泛的研究。研究表明,利用该基因可以很好地解决昆虫属、种及种下分类单元的系统发育问题,但是在解决科、亚科等高级阶元的系统发育关系时仍存在一些局限,COⅡ基因与其他mtDNA及核基因的联合分析能够更好地解决昆虫的系统发育问题。     

蚜虫体色多态性及生态进化功能

体色多态性在蚜虫中普遍存在,是探索生物适应环境机制及生态进化功能的一个优良范式。尽管蚜虫体色多态性被认知已经有两个多世纪,但其内在的机制仍然不甚明了。本文从蚜虫体色多态性的表现形式、体色的组成部分及色素种类、影响体色多态的重要因子、体色多态的生态功能及维持体色多态性的机制等方面综述有关研究进展,为进一步研究蚜虫体色分化的内在机理、体色多态的维持机制及体色多态的生态进化功能等提供方向和线索。     

Insect herbivores associated with Baccharis dracunculifolia (Asteraceae): responses of gall-forming and free-feeding insects to latitudinal variation

The spatial heterogeneity hypothesis has been invoked to explain the increase in species diversity from the poles to the tropics: the tropics may be more diverse because they contain more habitats and micro-habitats. In this paper, the spatial heterogeneity hypothesis prediction was tested by evaluating the variation in richness of two guilds of insect herbivores (gall-formers and free-feeders) associated with Baccharis dracunculifolia (Asteraceae) along a latitudinal variation in Brazil. The seventeen populations of B. dracunculifolia selected for insect herbivores sampling were within structurally similar habitats, along the N-S distributional limit of the host plant, near the Brazilian sea coast. Thirty shrubs were surveyed in each host plant population. A total of 8 201 galls and 864 free-feeding insect herbivores belonging to 28 families and 88 species were sampled. The majority of the insects found on B. dracunculifolia were restricted to a specific site rather than having a geographic distribution mirroring that of the host plant. Species richness of free-feeding insects was not affected by latitudinal variation corroborating the spatial heterogeneity hypothesis. Species richness of gall-forming insects was positively correlated with latitude, probably because galling insect associated with Baccharris genus radiated in Southern Brazil. Other diversity indices and evenness estimated for both gall-forming and free feeding insect herbivores, did not change with latitude, suggesting a general structure for different assemblages of herbivores associated with the host plant B. dracunculifolia. Thus it is probable that, insect fauna sample in each site resulted of large scale events, as speciation, migration and coevolution, while at local level, the population of these insects is regulated by ecological forces which operate in the system.     

论我国昆虫多样性的保护与利用

本文论述了保护昆虫多样性的意义、我国昆虫多样性的基本特点及面临的问题、昆虫多样性的保护战略和利用对策。文中强调指出,昆虫是生物界的一个主要类群,在我国,需要防治的害虫大约只占全部昆虫种类数的1%,其余种类对人类都是有益或者是中性的,它们不仅可以作为显花植物的传粉者、为人类提供食物和各种工业原料,而且可以作为许多害虫或杂草的天敌,以及用于环境净化和科学研究。我国由于地域辽阔,生境复杂,因此,昆虫种类极为丰富,珍稀物种及有益昆虫较多。然而,由于受到人类活动的干扰,我国昆虫多样性面临着生境遭到破坏,物种濒于灭绝,天敌大量减少等问题。为了有效地保护和利用我国的昆虫资源,作者提出了一些战略和对策。     

森林冠层昆虫多样性研究方法

森林冠层是森林昆虫栖息、取食、避敌的重要生境,其中生活着十分丰富的昆虫物种。但由于乔木树体高大,冠层难于接近,在很大程度上限制了冠层昆虫多样性的研究。冠层昆虫类群结构的划分和冠层昆虫取样技术也是冠层昆虫多样性研究的重要基础。文章综述当前冠层接近和冠层昆虫抽样技术的最新进展,并评述冠层昆虫类群结构划分的方法。     

Insect diversity in Cape fynbos and neighbouring South African vegetation

Aim  It has often been suggested that South Africa's Cape fynbos shrublands, although extremely rich in plant species, are poor in insects, thus representing a notable exception from the broad plant–insect diversity relationship. The aims of this study were to compare the diversity patterns of plant-inhabiting insects in fynbos and the vegetation of three neighbouring biomes (grassland, subtropical thicket, and Nama-karoo), and to test for a general relationship between plant diversity and insect diversity across these biomes.
Location  South-western to south-eastern South Africa.
Methods  We conducted seasonal plant surveys and sweep insect sampling in 10 × 10 m plots in the Baviaanskloof Conservation Area (Eastern Cape), where all four biomes occur. We also conducted once-only collections in the core area of each biome.
Results  Fynbos plots had insect diversity values similar to those of grassland and subtropical thicket (a dense, evergreen and spinescent shrubland with a high abundance of succulents and climbers), and significantly higher than Nama-karoo (an open, semiarid shrubland). A remarkably strong positive relationship was found between plant and insect species richness.
Main conclusions  Previous generalizations were based on a few insect groups (e.g. butterflies, under-represented in fynbos), but ignored published results on other groups (e.g. galling insects, which are in fact over-represented in this vegetation). We show that, overall, insect diversity in fynbos is comparable to that of neighbouring biomes. Fynbos vegetation does not represent a significant exception from the broad positive relationship between plant diversity and insect diversity.     

灭幼脲Ⅲ号对马尾松林昆虫群落多样性的影响研究

１９９５年７月至１９９６年６月在湘中丘陵区马尾松林内用灭幼脲Ⅲ号作的喷药试验结果表明,灭幼脲Ⅲ号不仅直接影响鳞翅目昆虫的物种组成主多样性水平,而且对膜翅目昆虫（主要是蚂蚁）和蜘蛛的物种组成及多样性水平有间接影响。在时间过程中,施药区鳞翅目和直翅目昆虫的多样性水平有一定程度的下降,但下降程度不如对照区大,膜翅目和蜘蛛的多样性水平则有较大程度的上升,因此林内昆虫群落趋于相对稳定。由于药剂对蚜虫种群无影     

Beneficial interactions between insects and gut bacteria

Insects are amongst the most successful of animals, both in terms of diversity and in colonizing all ecological niches. Recent studies have highlighted the benefi ciary roles that bacteria play in the success and establishment of insects. By adopting techniques like 16S rRNA sequencing we are now in a position to understand the diversity of bacteria present in insect guts. It has been shown that some of these bacteria, like Wolbachia and Cardinium are involved in manipulating insect populations and distorting their sex ratio. Attempts have been made to culture these bacteria in insect cell lines, as they are recalcitrant to culture under normal microbiological conditions. The diversity of bacteria associated with insects and the functional role played by them in the insect is discussed below.     

Climate-driven diversity dynamics in plants and plant-feeding insects

The origin of species-rich insect-plant food webs has traditionally been explained by diversifying antagonistic coevolution between plant defences and herbivore counter-defences. However, recent studies combining paleoclimatic reconstructions with time-calibrated phylogenies suggest that variation in global climate determines the distribution, abundance and diversity of plant clades and, hence, indirectly influences the balance between speciation and extinction in associated herbivore groups. Extant insect communities tend to be richest on common plant species that have many close relatives. This could be explained either by climate-driven diffuse cospeciation between plants and insects, or by elevated speciation and reduced extinction in herbivore lineages associated with expanding host taxa (resources). Progress in paleovegetation reconstructions in combination with the rapidly increasing availability of fossil-calibrated phylogenies provide means to discern between these alternative hypotheses. In particular, the 'Diffuse cospeciation' scenario predicts closely matching main diversification periods in plants and in the insects that feed upon them, while the 'Resource abundance-dependent diversification' hypothesis predicts that both positive and negative responses of insect diversity are lagged in relation to host-plant availability. The dramatic Cenozoic changes in global climate provide multiple possibilities for studying the mechanisms by which climatic shifts may drive diversity dynamics in plants and insect herbivores.     

Meta-analysis of tree diversity effects on the abundance,diversity and activity of herbivores' enemies

The natural enemies hypothesis predicts that the abundance and diversity of antagonists such as predators and parasitoids of herbivores increases with the diversity of plants, which can lead to more effective top-down control of insect herbivores. However, although the hypothesis has received large support in agricultural systems, fewer studies have been conducted in forest ecosystems and a comprehensive synthesis of previous research is still lacking.We conducted a meta-analysis of 65 publications comparing the diversity, abundance or activity of various groups of natural enemies (including birds, bats, spiders and insect parasitoids) in pure vs. mixed forest stands. We tested the effects of forest biome, natural enemy taxon and type of study (managed vs experimental forest).We found a significant positive effect of forest tree diversity on natural enemy abundance and diversity but not on their activity. The effect of tree diversity on natural enemies was stronger towards lower latitudes but was not contingent on the natural enemy taxon level.Overall, our study contributes toward a better understanding of the “natural enemies hypothesis” in forest systems and provides new insights about the mechanisms involved. Furthermore, we outline potential avenues for strengthening forest resistance to the growing threat of herbivorous insects.