昆虫视觉的研究及其应用

在科学技术高度发展,现代化工业极为发达的今天,作为现代社会的三大资源之一的“信息”,其价值已经超过物质和能量资源,成为人类社会生产力快速发展的必要条件,同时,一个高速有效的信息处理系统在工业、农业、国防和科学技术等领域发挥了越来越大的作用。以微电子和电子计算机为基础的一个完整的现代化信息系统,由信息的采集与存储、处理与提取、传输与交换三大部分组成。尽管多功能、超大规模集成电路的出现,使信息系统逐渐走向微型化,并在一定程度上降低了功耗,提高了速度和可靠性,但是,无论在体积、功耗、速度、可靠性以及寿…     

日行性朱红毛斑蛾和夜行性斜纹夜蛾成虫复眼结构及其对光暗条件反应的比较研究

【目的】本研究旨在比较日行性朱红毛斑蛾Phauda flammans与夜行性斜纹夜蛾Spodoptera litura复眼的外部形态和内部显微结构及自然光照和全黑暗条件下小眼结构和色素颗粒变化的异同,为进一步探索日行性和夜行性蛾类基于视觉的生存和繁殖机制奠定基础。【方法】采用扫描电子显微镜观察朱红毛斑蛾与斜纹夜蛾成虫复眼外部形态并测定其成虫复眼小眼数量与复眼长度等参数,运用石蜡切片技术观察其成虫复眼内部组织结构,通过超景深显微系统观察其成虫复眼在自然光照和全黑暗环境中的光暗适应状态。【结果】斜纹夜蛾成虫的复眼长度[(1.67±0.05) mm]和宽度[1.57±0.02) mm]及小眼数量(8 816.38±25.56)均显著大于朱红毛斑蛾成虫的复眼长度[(0.74±0.11) mm]和宽度[(0.66±0.01) mm]及小眼数量(820.55±23.69)。自然光照和全黑暗条件下,斜纹夜蛾成虫复眼发生了明显的明暗适应状态的转变,而朱红毛斑蛾成虫的复眼无明显变化。自然光照条件下,朱红毛斑蛾小眼中的色素颗粒均匀分布于感杆束和晶锥两侧,斜纹夜蛾的则分布在晶锥和透明带之间;全黑暗条件下,两...     

蜜蜂复眼的视觉通路研究进展

视觉通路的研究在神经科学、 仿生应用和医学治疗上都具有十分重要的意义。西方蜜蜂Apis mellifera作为神经生物学研究的重要模式生物已被广泛地应用于视觉通路的研究。蜜蜂的视觉器官包括1对复眼和3只单眼, 复眼是形成视觉的主要感觉器官。视叶是蜜蜂传递和处理视觉信息的主要神经构造, 它包括视神经节层、 视髓质层、 视小叶和前视结节4个等级的神经纤维网。复杂的视觉信息在经过大脑的各级神经时被分离, 以许多空间隔离的并行连续的视觉通路传递和加工, 然后汇集到高级脑中枢, 部分甚至与其他感觉模态的信息相整合, 最终输出有效信息来调控蜜蜂的各种行为。本文按照信息在视叶中逐级传递的顺序对蜜蜂复眼的视觉通路研究进展进行综述。     

昆虫弦音器及其声音感受分子机制

弦音器是昆虫类特有的一种机械感受器,亦称弦音感受器或剑梢感受器。它主要具有感知外界声压和体内肌肉运动的听觉功能,研究弦音器的机能结构对揭秘昆虫听觉的神经机制有重要的科学意义。本文从弦音器多样性和进化入手,重点综述了弦音器的微细结构、基因功能定位、声音感受分子机制及其声压增幅分子生物物理学原理,为昆虫听觉仿生学的研究提供了理论依据。     

昆虫弦音器及其声音感受分子机制

弦音器是昆虫类特有的一种机械感受器,亦称弦音感受器或剑梢感受器。它主要具有感知外界声压和体内肌肉运动的听觉功能,研究弦音器的机能结构对揭秘昆虫听觉的神经机制有重要的科学意义。本文从弦音器多样性和进化入手,重点综述了弦音器的微细结构、基因功能定位、声音感受分子机制及其声压增幅分子生物物理学原理,为昆虫听觉仿生学的研究提供了理论依据。     

视觉信号在昆虫检测植物寄主中的作用

植物为数十万种昆虫提供各种资源,如食物、交配、产卵和躲避天敌的场所。目前对昆虫检测植物寄主的研究主要关注昆虫嗅觉系统和植物寄主挥发物之间的相互作用,对昆虫视觉系统发挥的作用关注较少。近年来,对昆虫视觉器官、光行为反应及分子生物学的研究表明,昆虫具有优异的视觉能力,能够辨别植物寄主的颜色、大小和轮廓,应该将视觉纳入昆虫检测植物寄主的研究中。昆虫能够利用视觉信号准确检测寄主,远距离时,主要依靠植物寄主轮廓检测寄主,近距离时,寄主的大小、颜色和形状发挥重要作用。利用昆虫视觉识别寄主的专一性研制诱捕装置,可为害虫的监测和防治提供一定的理论基础。     

模拟昆虫视觉-行为抉择的强化学习模型

视觉信息用于行为抉择的过程是一个极其复杂的脑信息处理过程,昆虫或动物对外界环境的学习是以价值来控制的,并可影响其行为抉择,研究这一过程对揭示人类自身脑运行机制有重要意义.文章在郭爱克研究小组果蝇实验提供的生物依据基础上,提出了一种模拟果蝇视觉-行为抉择的神经网络模型.该模型引入了价值和基于价值的强化学习算法,应用于输入视觉图像的强化学习,以此建立果蝇脑内多巴胺和蘑菇体对于抉择判断的价值体系.模拟的结果表明,该模型可以模拟果蝇视觉信息的学习和行为抉择过程,其结果与生物实验相符,同时也为机器人视觉信息控制行为抉择的应用提供了基础.     

昆虫信息素结合蛋白及其分子运输机制和生理功能研究进展

昆虫信息素结合蛋白是气味结合蛋白多基因家族的一个分支,在昆虫识别性信息素过程中起重要作用。该文从信息素结合蛋白的分子特征、与信息素分子的结合及释放机制、生理功能和进化基因组学等方面进行了综述,针对鳞翅目昆虫进行了重点阐述。     

植食性昆虫取食行为过程及机制研究

昆虫取食行为包括定向、趋性、辨认、取食等一系列的活动,涉及复杂的行为生理过程,如视觉、嗅觉、味觉感受及神经调控等。昆虫取食行为不仅受外界物理环境因素、寄主植物化学成份影响,而且跟昆虫自身生理状态紧密相关。本文综述了昆虫取食过程、寄主定位的感受机制、神经肽调节机制、影响取食的理化因素、环境因素等方面的研究进展,旨在为深入研究昆虫与环境关系、开发害虫取食行为调控新技术提供参考。     

昆虫表皮蛋白及其基因表达调控机理的研究进展

昆虫表皮蛋白(insectcuticular proteins,ICP)是结构蛋白,它和几丁质一起组成昆虫抵御外界环境的屏障——角质层。根据保守性基序的不同,ICP可分为CPR、CPF、CPFL、CPG和CPT5家族。它们都有独特的结构与性质。环境、激素、转录因子和内含子等共同影响昆虫表皮蛋白基因(insect cuticular protein genes,ICPG)的表达,进而使ICPG具有时期和组织特异性。ICP和ICPG被认为是研究昆虫蜕皮与变态的调控机理和理解昆虫发育期角质层在生物化学、物理化学以及结构上的修饰的重要模型,受到越来越多的重视。本文综述了ICP的分类以及环境、激素、转录因子和内含子等对ICPG表达的调控。     

Rhodopsin population genetics and local adaptation: variable dim-light vision in sand gobies is illuminated

The visual pigments of fish are thought to be adapted to the variable spectral qualities of aquatic light environments. Most research on the role of natural selection on the evolution of rhodopsins and dim-light vision in fish has focused on variation among species and higher taxa. In this issue, Larmuseau et al. reveal substantial intraspecific sequence variation in RH1 (the rhodopsin gene) in sand gobies ( Pomatoschistus minutus ). Using population genetics and molecular evolution approaches, they detect positive selection on RH1 and find evidence for adaptation to local light conditions.     

Molecular evolution of bat color vision genes

The two suborders of bats, Megachiroptera (megabats) and Microchiroptera(microbats), use different sensory modalities for perceivingtheir environment. Megabats are crepuscular and rely on a well-developedeyes and visual pathway, whereas microbats occupy a nocturnalniche and use acoustic orientation or echolocation more thanvision as the major means of perceiving their environment. Inview of the differences associated with their sensory systems,we decided to investigate the function and evolution of colorvision (opsin genes) in these two suborders of bats. The middle/longwavelength (M/L) and short wavelength (S) opsin genes were sequencedfrom two frugivorous species of megabats, Haplonycteris fischeriand Pteropus dasymallus formosus, and one insectivorous speciesof microbat, Myotis velifer. Contrary to the situation in primates,where many nocturnal species have lost the functional S opsingene, both crepuscular and strictly nocturnal species of batsthat we examined have functional M/L and S opsin genes. Surprisingly,the S opsin in these bats may be sensitive to UV light, whichis relatively more abundant at dawn and at dusk. The M/L opsinin these bats appears to be the L type, which is sensitive tored and may be helpful for identifying fruits among leaves orfor other purposes. Most interestingly, H. fischeri has a recentduplication of the M/L opsin gene, representing to date theonly known case of opsin gene duplication in non-primate mammals.Some of these observations are unexpected and may provide insightsinto the effect of nocturnal life on the evolution of opsingenes in mammals and the evolution of the life history traitsof bats in general.     

Anatomical and physiological evidence for polarisation vision in the nocturnal bee <Emphasis Type="Italic">Megalopta genalis</Emphasis>

The presence of a specialised dorsal rim area with an ability to detect the e-vector orientation of polarised light is shown for the first time in a nocturnal hymenopteran. The dorsal rim area of the halictid bee Megalopta genalis features a number of characteristic anatomical specialisations including an increased rhabdom diameter and a lack of primary screening pigments. Optically, these specialisations result in wide spatial receptive fields (Δρ = 14°), a common adaptation found in the dorsal rim areas of insects used to filter out interfering effects (i.e. clouds) from the sky. In this specialised eye region all nine photoreceptors contribute their microvilli to the entire length of the ommatidia. These orthogonally directed microvilli are anatomically arranged in an almost linear, anterior–posterior orientation. Intracellular recordings within the dorsal rim area show very high polarisation sensitivity and a sensitivity peak within the ultraviolet part of the spectrum.     

Rhabdom evolution in butterflies: insights from the uniquely tiered and heterogeneous ommatidia of the Glacial Apollo butterfly, Parnassius glacialis

The eye of the Glacial Apollo butterfly, Parnassius glacialis, a 'living fossil' species of the family Papilionidae, contains three types of spectrally heterogeneous ommatidia. Electron microscopy reveals that the Apollo rhabdom is tiered. The distal tier is composed exclusively of photoreceptors expressing opsins of ultraviolet or blue-absorbing visual pigments, and the proximal tier consists of photoreceptors expressing opsins of green or red-absorbing visual pigments. This organization is unique because the distal tier of other known butterflies contains two green-sensitive photoreceptors, which probably function in improving spatial and/or motion vision. Interspecific comparison suggests that the Apollo rhabdom retains an ancestral tiered pattern with some modification to enhance its colour vision towards the long-wavelength region of the spectrum.     

Retinal and optical adaptations for nocturnal vision in the halictid bee<Emphasis Type="Italic"> Megalopta genalis</Emphasis>

The apposition compound eye of a nocturnal bee, the halictid Megalopta genalis, is described for the first time. Compared to the compound eye of the worker honeybee Apis mellifera and the diurnal halictid bee Lasioglossum leucozonium, the eye of M. genalis shows specific retinal and optical adaptations for vision in dim light. The major anatomical adaptations within the eye of the nocturnal bee are (1) nearly twofold larger ommatidial facets and (2) a 4–5 times wider rhabdom diameter than found in the diurnal bees studied. Optically, the apposition eye of M. genalis is 27 times more sensitive to light than the eyes of the diurnal bees. This increased optical sensitivity represents a clear optical adaptation to low light intensities. Although this unique nocturnal apposition eye has a greatly improved ability to catch light, a 27-fold increase in sensitivity alone cannot account for nocturnal vision at light intensities that are 8 log units dimmer than during daytime. New evidence suggests that additional neuronal spatial summation within the first optic ganglion, the lamina, is involved.B.G. is thankful for travel awards from the Royal Physiographic Society, the Per Westlings Fond, the Foundation of Dagny and Eilert Ekvall and the Royal Swedish Academy of Sciences. E.J.W. is grateful for the support of a Smithsonian Short-Term Research Fellowship, the Swedish Research Council, the Crafoord Foundation, the Wenner-Gren Foundation and the Royal Physiographic Society of Lund for their ongoing support     

Early duplication and functional diversification of the opsin gene family in insects

Recent analysis of the complete mosquito Anopheles gambiae genome has revealed a far higher number of opsin genes than for either the Drosophila melanogaster genome or any other known insect. In particular, the analysis revealed an extraordinary opsin gene content expansion, whereby half are long wavelength-sensitive (LW) opsin gene duplicates. We analyzed this genomic data in relationship to other known insect opsins to estimate the relative timing of the LW opsin gene duplications and to identify "missing" paralogs in extant species. The inferred branching patterns of the LW opsin gene family phylogeny indicate at least one early gene duplication within insects before the emergence of the orders Orthoptera, Mantodea, Hymenoptera, Lepidoptera, and Diptera. These data predict the existence of one more LW opsin gene than is currently known from most insects. We tested this prediction by using a degenerate PCR strategy to screen the hymenopteran genome for novel LW opsin genes. We isolated two LW opsin gene sequences from each of five bee species, Bombus impatiens, B. terrestris, Diadasia afflicta, D. rinconis, and Osmia rufa, including 1.1 to 1.2 kb from a known (LW Rh1) and 1 kb from a new opsin gene (LW Rh2). Phylogenetic analysis suggests that the novel hymenopteran gene is orthologous to A. gambiae GPRop7, a gene that is apparently missing from D. melanogaster. Relative rate tests show that LW Rh2 is evolving at a slower rate than LW Rh1 and, therefore, may be a useful marker for higher-level hymenopteran systematics. Site-specific rate tests indicate the presence of several amino acid sites between LW Rh1 and LW Rh2 that have undergone shifts in selective constraints after duplication. These sites and others are discussed in relationship to putative structural and functional differences between the two genes.     

Dorsal landmark navigation in a Neotropical nocturnal bee

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Gene duplication is an evolutionary mechanism for expanding spectral diversity in the long-wavelength photopigments of butterflies

Butterfly long-wavelength (L) photopigments are interesting for comparative studies of adaptive evolution because of the tremendous phenotypic variation that exists in their wavelength of peak absorbance (lambda(max) value). Here we present a comprehensive survey of L photopigment variation by measuring lambda(max) in 12 nymphalid and 1 riodinid species using epi-microspectrophotometry. Together with previous data, we find that L photopigment lambda(max) varies from 510-565 nm in 22 nymphalids, with an even broader 505- to 600-nm range in riodinids. We then surveyed the L opsin genes for which lambda(max) values are available as well as from related taxa and found 2 instances of L opsin gene duplication within nymphalids, in Hermeuptychia hermes and Amathusia phidippus, and 1 instance within riodinids, in the metalmark butterfly Apodemia mormo. Using maximum parsimony and maximum likelihood ancestral state reconstructions to map the evolution of spectral shifts within the L photopigments of nymphalids, we estimate the ancestral pigment had a lambda(max) = 540 nm +/- 10 nm standard error and that blueshifts in wavelength have occurred at least 4 times within the family. We used ancestral state reconstructions to investigate the importance of several amino acid substitutions (Ile17Met, Ala64Ser, Asn70Ser, and Ser137Ala) previously shown to have evolved under positive selection that are correlated with blue spectral shifts. These reconstructions suggest that the Ala64Ser substitution has indeed occurred along the newly identified blueshifted L photopigment lineages. Substitutions at the other 3 sites may also be involved in the functional diversification of L photopigments. Our data strongly suggest that there are limits to the evolution of L photopigment spectral shifts among species with only one L opsin gene and that opsin gene duplication broadens the potential range of lambda(max) values.     

Polarization vision in water insects and insects living on a moist substrate

Summary Light polarized by reflection was tested in the field for its attractiveness to flying insects. Attracted insects include bugs: some living in water (Corixidae, Notonectidae, Pleidae), others living on its surface (Gerridae) or near it (Saldidae). Beetles were also attracted: some are aquatic (Hydrophilinae, Dytiscidae, Haliplidae, Hydraenidae), others inhabit moist substrates (Sphaeridiinae). Also included are Chironomidae among other nematocerans. Non-polarized reflected light failed to attract any of these insects even at intensities far higher.Three response groups emerge. One is attracted whenever the degree of polarization is high in the UV-range, irrespectively of the degree of polarization in other wavelength ranges, and irrespectively of colour or brightness of the background beneath the polarizing, reflecting surface. The polarization vision of these insects operates in the UV-range. Another group was attracted only by the reflecting surface over a dark background, where the reflected light was highly polarized at all wave-lengths visible to insects. The third group ranges in between.Some Helophorus species behave in spring like members of the first group; in fall, like members of the second group.The distribution of the above response groups within various taxa is provided. Sensory mechanisms and eco-physiological implications are discussed.Abbreviations B matt black surface - b; y; w; a black, yellow white material and aluminum foil, reflection characteristics as described in the text; - G glass - G/b; G/y; G/w; G/a glass panes on different materials - Gb, y, w; Gb, y, Gb types of animals differing in behavior