昆虫感觉气味的细胞与分子机制研究进展

昆虫作为地球上最为成功的类群,已经成功地进化了精细的化学感受系统,通过化学感受系统适应各种复杂的环境,保持种群的繁荣。自1991年在动物中发现嗅觉受体基因以来,关于昆虫感受化学信息的周缘神经系统的分子和细胞机制方面的进展十分迅速。文章主要就昆虫周缘神经系统的感受化学信息的分子和细胞机制进行综述。首先对昆虫感觉气味的细胞机制的研究进展进行简要介绍。昆虫嗅觉神经元在感受化学信息过程中起着极为重要的作用,昆虫嗅觉神经元上表达的嗅觉受体不同而执行着各异的功能。各种嗅觉神经元对于化学信息的感受谱有较大的区别;嗅觉神经元对化学信息类型、浓度、流动动态等产生相应的电生理特征反应。研究表明同一种神经原可以感受多种化学信息,而一种化学信息也可以被多种神经原所感受。由神经原对化学信息感受所形成的特征组合就是感受化学信息的编码。其次较为详细地论述与昆虫感受气味分子相关的一些蛋白质的研究进展。气味分子结合蛋白是一类分子量较小、水溶性的蛋白,主要位于化学感受器神经原树突周围的淋巴液中。在结构上的主要特征是具有6个保守的半光氨酸和由6个α螺旋组成的结合腔。自1981年发现以来,已经在40余种昆虫中发现上百种。由于研究手段的不断进步,已经对该类蛋白的表达特征、结合特性以及三维结构和结合位点进行了大量的研究,提出了多个可能的功能假说,在诸多的假说中,较为广泛接受的是气味分子结合蛋白在昆虫感觉气味的过程中,是与疏水性的气味分子相结合,并将气味分子运输到嗅觉神经原树突膜上的嗅觉受体上。这些处于树突膜上的嗅觉受体则是昆虫感觉气味过程中的另一个十分重要的蛋白质。目前,已经在果蝇、按蚊、蜜蜂和家蚕等10余个昆虫种类中发现上百个嗅觉受体蛋白基因。这类蛋白是跨膜蛋白,一般具有7个跨膜区,整个蛋白的氨基酸残基在400～600个。昆虫的嗅觉受体蛋白的N-端在胞内,而C-端在胞外,这与G耦联蛋白不同。而且,昆虫的一个嗅觉神经元可以表达1～3个嗅觉受体蛋白,也与哺乳动物的一个神经元只表达一种受体蛋白有所不同。每种嗅觉受体可以感受多种气味分子,而一种气味分子可以被多个嗅觉受体所感知,这样组成了感受化学信息的编码谱。最近采用基因敲除技术和膜片钳技术研究发现,昆虫的嗅觉受体蛋白在信号传导中也有特殊性,即嗅觉受体可以直接作为离子通道,而引起动作电位。还有近来的研究表明,神经膜蛋白对于果蝇的性信息素感受神经元感受性信息素cVA是必要的。实际上,昆虫对于化学信息的感受和信号的转导,并不是上述蛋白单独起作用完成的,而是多种蛋白相互作用的结果。论文最后对该领域研究内容进行了展望。     

红彩真猎蝽成虫触角、喙和前足跗节感受器的扫描电镜观察

利用扫描电镜对红彩真猎蝽成虫的触角、喙、前足跗节感受器进行观察。结果表明：红彩真猎蝽触角上分布4种类型的感受器,分别为毛形感受器、刺形感受器、锥形感受器和腔锥形感受器。其中,毛形感受器、刺形感受器各有3种形态,锥形感受器和腔锥形感受器各有2种形态,雌、雄性成虫个体间触角感受器类型、数量及分布未发现明显差异。喙的末端分布3种类型感受器,分别为毛形感受器、刺形感受器和锥形感受器,其中毛形感受器1种形态,刺形感受器2种形态,锥形感受器有3种形态。前足跗节末节存在刺形感受器和锥形感受器,其中刺形感受器有3种形态,锥形感受器有4种形态。     

豆柄瘤蚜茧蜂触角感受器的扫描电镜观察(英文)

利用扫描电镜对豆柄瘤蚜茧蜂Lysiphlebus fabarum的触角感受器进行了观察, 发现有7 种感受器, 分别为毛形感受器、刺形感受器Ⅰ型、刺形感受器Ⅱ型、锥形感受器、腔锥形感受器Ⅰ型、腔锥形感受器Ⅱ型和板形感受器。毛形感受器是数量最多的感器; 除了腔锥形感受器Ⅱ型只在雌虫触角发现外, 雌、雄触角感受器的类型和结构没有较大的差别, 并且腔锥形感受器Ⅱ是数量最少的感器。     

柑橘大实蝇成虫超微感器的扫描电镜观察

利用扫描电镜观察了柑橘大实蝇Bactrocera minax成虫触角、下颚须、平衡棒、前足跗节和产卵器的感器。共发现5种感受器,包括毛形感受器、微毛感受器、刺形感受器、锥形感受器和腔锥形感受器,其中,柑橘大实蝇的触角分布有毛形感受器、微毛感受器、刺形感受器和锥形感受器,下颚须有微毛感受器、刺形感受器和锥形感受器分布,平衡棒分布有微毛感受器和刺形感受器,足跗节有毛形感受器和刺形感受器分布。产卵管针突缩入产卵器基节中,其上有毛形感受器和腔锥形感受器分布,产卵管基节有较多毛形感受器。     

冬虫夏草寄主蒲氏钩蝠蛾雄成虫触角感受器的观察

蒲氏钩蝠蛾Thitarodes pui(Zhang et al.)是冬虫夏草寄主昆虫之一,其雄成虫触角感受器在求偶交配过程中起主要作用。本研究应用电子扫描显微镜对蒲氏钩蝠蛾雄成虫触角上的化学感受器进行观察。结果发现,雄成虫触角上有7种感受器,即毛形感受器、刺形感受器、锥形感受器、腔锥形感受器、钟形感受器、Bhm氏鬃毛和鳞形感受器,其中以毛形感受器和鳞形感受器数目最多,腔锥感受器又分为长栓形和短栓形两种。综合本研究结果与已知蝠蛾的触角感受器,发现蝠蛾触角感受器在表面结构、感受器类型等方面与其它鳞翅目昆虫存在差异。     

孟氏隐唇瓢虫的触角感受器

本文使用场发射扫描电子显微镜对孟氏隐唇瓢虫Cryptolaemus montrouzieri Mulsant雌雄成虫的触角和触角感受器进行了观察和研究，并对触角形态，感受器形态、类型、数量及分布进行了统计和分析。孟氏隐唇瓢虫雌雄成虫触角均由柄节，梗节及8个鞭小节组成。观察到7种触角感受器：四种锥形感受器（sba），四种刺形感受器（sch），四种毛形感受器（str），一种腔锥形感受器（sco），一种耳形感受器（sau），一种腔形感受器（scl），一种Bhm氏鬃毛（sbm）。毛形感受器和刺形感受器数量最多，其他类型感受器数量都较少。Bhm氏鬃毛只存在于柄节和梗节。第八鞭小节的顶端感受器种类最丰富，被六种感受器稠密覆盖。雌雄触角大小、感受器类型都没有明显差异。根据感受器的分布和以前的相关报道，推测孟氏隐唇瓢虫的毛形感受器可能是信息素接收者，刺形感受器可能是机械性刺激感受器和化学感受器，锥形感受器和腔锥形感受器可能都是植物挥发物接受者，化学和温湿度感受器，耳形感受器或许承担物理或者嗅觉器官的功能，而Bhm氏鬃毛或许能感知触角的位置和活动。     

甘草胭脂蚧雌成虫触角感受器超微结构（英文）

【目的】甘草胭脂蚧Porphyrophora sophorae Arch.是一种典型的土栖性蚧虫。本研究旨在了解该虫触角的结构及其对土栖环境的适应性。【方法】利用光学显微镜、扫描和透射电子显微镜对甘草胭脂蚧雌成虫触角以及触角感受器进行了观察。【结果】甘草胭脂蚧雌成虫触角由9节组成,各触角节粗而短,各节间连接紧密,使触角形态呈现出较为粗壮的特点。在触角上分布着4种感受器29~48个,包括2~5个B9hm氏鬃毛,5~12个无孔毛形感受器,10~15个腔锥形感受器和11~22个多孔钉形感受器。根据各感受器的结构特点,判断它们分别具有自体感受、触觉感受、温湿度感受和嗅觉感受的功能。触角感受器主要分布在触角的3个节上,分别是:柄节,具2~4个B9hm氏鬃毛;第3鞭节,分布有6~10个腔锥形感受器;第7鞭节(即顶节),大多数的感受器都分布在这一节的端部,包括3~8个腔锥形感受器,4~11个无孔毛形感受器和11~22个多孔钉形感受器。而在触角的其他节上几乎没有感受器分布。【结论】甘草胭脂蚧雌成虫触角有着许多不同于其他蚧虫触角的特点,这些特点是与其土栖性的生活方式相适应的。     

中红侧沟茧蜂触角感受器的扫描电镜观察

利用扫描电镜对中红侧沟茧蜂Microplitis mediator的触角感受器进行了观察,发现了6个类型的感器,分别为毛形感器、板形感器、刺形感器、钟形感器、锥形感器、腔锥形感器。其中,毛形感器具有2种形态,锥形感器具有4种形态。钟形感器仅分布于雌蜂的触角上,锥形感器Ⅲ和Ⅳ仅分布于雄蜂的触角上。结合感受器的形态、分布和已报道的触角电位反应数据,对各感受器的功能进行了推测。     

梨小食心虫触角感受器雌雄二型的超微研究

梨小食心虫是果树上的一种重要害虫。本文采用扫描电子显微镜技术(SEM)对成虫离体触角外部形态进行观察,以Onagbola和Fadamiro(2008)为分类标准,对梨小食心虫的触角感受器重新进行分类。结果显示,梨小食心虫触角为线状,由柄节、梗节和鞭节构成,鞭节细分为38-45个亚节。雌、雄蛾共有8种触角感受器,分别为无孔栓锥形感受器、无孔B9hm's鬃毛、单孔刺形感受器、多孔毛形感受器、多孔锥形感受器、多孔腔锥形感受器、多孔耳形感受器和芽孢形感受器(只在雌蛾触角上观察到)。感受器在类型、形态和数量上存在雌雄二型现象。耳形感受器数量在雌雄间差异显著,雌雄蛾刺形感受器、栓锥形感受器、毛形感受器、锥形感受器、腔锥形感受器长度差异显著,并对其功能进行了推测。     

中华蜜蜂工蜂触角感受器的扫描电镜观察

对中华蜜蜂(Apis cerana)工蜂触角感受器的扫描电镜观察,见到在触角上有九种类型的感受器,它们是板形感器、腔锥感器、坛形感器、钟形感器、锥形感器、毛形感器A、毛形感器B、毛形感器C和D、缘感器以及各种类型的刚毛等.对于这些感受器的外部形态和分布部位进行了详细地观察和描述,发现中华蜜蜂与西方意蜂(Apis mellifera)有差异.     

Solitary and gregarious locusts differ in circadian rhythmicity of a visual output neuron

Locusts demonstrate remarkable phenotypic plasticity driven by changes in population density. This density dependent phase polyphenism is associated with many physiological, behavioral, and morphological changes, including observations that cryptic solitarious (solitary-reared) individuals start to fly at dusk, whereas gregarious (crowd-reared) individuals are day-active. We have recorded for 24-36 h, from an identified visual output neuron, the descending contralateral movement detector (DCMD) of Schistocerca gregaria in solitarious and gregarious animals. DCMD signals impending collision and participates in flight avoidance maneuvers. The strength of DCMD's response to looming stimuli, characterized by the number of evoked spikes and peak firing rate, varies approximately sinusoidally with a period close to 24 h under constant light in solitarious locusts. In gregarious individuals the 24-h pattern is more complex, being modified by secondary ultradian rhythms. DCMD's strongest responses occur around expected dusk in solitarious locusts but up to 6 h earlier in gregarious locusts, matching the times of day at which locusts of each type are most active. We thus demonstrate a neuronal correlate of a temporal shift in behavior that is observed in gregarious locusts. Our ability to alter the nature of a circadian rhythm by manipulating the rearing density of locusts under identical light-dark cycles may provide important tools to investigate further the mechanisms underlying diurnal rhythmicity.     

Effect of Paranosema locustae (Microsporidia) on the behavioural phases of Locusta migratoria (Orthoptera: Acrididae) in the laboratory

The ability of parasites to modify the behaviour of their hosts is a wide spread phenomenon, but the effects of microsporidian parasites on locust behaviour remain unexplored. Here the frequencies of directional changes (ND) and jumping (NJ) per minute of gregarious locusts infected with 2000 spores of the microsporidian parasite Paranosema locustae were significantly different from those of untreated locusts 10 and 16 days after infection, being similar to values for solitary nymphs. In contrast, the behaviour of locusts inoculated with the lower doses of 200 spores/locust was sometimes like that of solitary nymphs. At other times, behaviour was intermediate between solitary and gregarious, i.e. transitional. The rearing density did not affect the turning and jumping behaviour of infected locusts, and their behaviours were similar to those of solitary locusts at 10–16 days after infection. Our study demonstrates that infection with P. locustae may lead gregarious locusts to change some of their behaviour to that typical of solitary locusts.     

Effect of β-cyano-l-alanine on the water balance of Locusta migratoria

Administration of β-cyano-l-alanine (BCNA) to adult locusts results in a significant decrease in haemolymph volume within one day. Dehydration becomes acute within 2 to 3 days and causes death within 5 days. This syndrome is attributed to impaired ability of BCNA-treated locusts to reabsorb water into the haemolymph from the rectal lumen. Extracts of brains and last abdominal ganglia, or haemolymph of water deprived locusts have no effect on rectal water resorption in BCNA-treated locusts. The initial symptoms of BCNA toxicity can be temporarily alleviated by injection of water into the haemocoel. Chronic BCNA toxicity irreversibly disrupts the control of water balance in locusts.     

Grip and detachment of locusts on inverted sandpaper substrates

Locusts (Locusta migratoria manilensis) are characterized by their strong flying and grasping ability. Research on the grasping mechanism and behaviour of locusts on sloping substrates plays an important role in elucidating the mechanics of hexapod locomotion. Data on the maximum angles of slope at which locusts can grasp stably (critical angles of detachment) were obtained from high-speed video recordings at 215 fps. The grasping forces were collected by using two sensors, in situations where all left legs were standing on one and the right legs on the other sensor plate. These data were used to illustrate the grasping ability of locusts on slopes with varying levels of roughness. The grasping morphologies of locusts' bodies and tarsi were observed, and the surface roughness as well as diameters of their claw tips was measured under a microscope to account for the grasping mechanism of these insects on the sloping substrate. The results showed that the claw tips and part of the pads were in contact with the inverted substrate when the mean particle diameter was in the range of 15.3-40.5 μm. The interaction between pads and substrates may improve the stability of contact, and claw tips may play a key role in keeping the attachment reliable. A model was developed to explain the significant effects of the relative size of claw tips and mean particle diameter on grasping ability as well as the observed increase in lateral force (2.09-4.05 times greater than the normal force during detachment) with increasing slope angle, which indicates that the lateral force may be extremely important in keeping the contact reliable. This research lays the groundwork for the probable design and development of biomimetic robotics.     

白洋淀蝗虫分布调查及其防治

1998～ 2 0 0 2年对白洋淀蝗区的蝗虫种类、分布、优势种群及蝗区水文、植被、土壤、天敌等进行了调查研究。调查表明 ,白洋淀蝗区有蝗总科昆虫 3 0种 ,隶属 6总科、2 2属 ,分布于白洋淀淀内湖泊蝗区、淀边内涝蝗区和淀外河泛蝗区 ;明确以东亚飞蝗Locustamigratoriamanilensis (Meyen)为主的 5个蝗虫优势种群及生活史 ,并根据不同蝗区类型 ,提出了蝗区治理区划、生态治理技术、应急化学防治等 3项防治技术和“两改一加强”防治手段     

蝗虫化学信息物质研究进展

详述了蝗虫主要化学信息物质的种类、功能及主要成分等研究进展。蝗虫化学信息物质包括种内通讯的化学信息素和种间通讯的化学信息物质。其中种内通讯的化学信息素主要有群居信息素、成熟信息素、产卵信息素(含促产卵化学信息素和群集产卵化学信息素)、性信息素、聚集信息素等;种间通讯的化学信息物质主要介绍用于防卫的化学信息物质,包括卵分泌的信息物质、特定腺体分泌的信息物质、粪便挥发的信息物质、口腔分泌物和内部毒素等,对其天敌均有一定的防卫作用。化学通讯是蝗虫种内和种间通讯联系的普遍方式。     

蝗虫成灾规律、影响因素及防控技术研究进展

蝗虫是最重要的全球农牧业害虫之一,其灾害不仅强烈影响生态系统功能和稳定性,还带来严重的经济损失。因蝗虫食性杂、适应性强、聚集为害等特点使其可持续治理成为一项复杂而长期的艰巨工作。本文从蝗虫灾变发生规律、影响因素(自身因素、非生物和生物因素)以及当前有效防控方法与技术进行综述,并从蝗虫种群动态变化规律以及其有效防控的理论与技术提出今后的研究方向,为将来蝗虫发生的内在机制研究以及对其进行绿色防控技术探索提供基础。     

Mermis nigrescens: physiological relationship with its host, the adult desert locust Schistocerca gregaria

Adult desert locusts were experimentally infected per os with 30, 50, or 60 Mermis nigrescens eggs, and changes in the host physiology were recorded. Larval nematodes were recovered from the hemocoel and counted at appropriate times after infection. The food consumption and blood volume of the host were unaffected by the parasitism, but the nematode significantly impaired the ability of male locusts to excrete the injected dye, amaranth, from their hemolymph. The total carbohydrate in the hemolymph of infected male and female locusts was severely depleted during the active growth period of the nematode and the possible utilization of these carbohydrates by the nematode are discussed. The total amino acid and protein levels in the blood of the host were unaffected by the nematode development, although concomittant changes in the levels of both these blood metabolites occurred in all locusts throughout the experimental period. However, although changes of this nature reflected the normal pattern of protein synthesis during oocyte development and oviposition in control locusts, the nematode suppressed oocyte development and caused oocyte resorption in the female host. The nematode did not significantly affect the level of total protein and amino acids in the flight muscles of male and female locusts, but a significant decrease in the level of fat body proteins and amino acids was recorded in infected hosts 16 and 21 days after infection. The possible effect of the nematode on protein metabolism by the host fat body is discussed in relation to the nutritional requirements of the nematode and involvement of the host endocrine system.     

Characteristics and expression patterns of histone-modifying enzyme systems in the migratory locust

The density-dependent phase polyphenism in locusts offers an excellent model to investigate the epigenetic regulatory mechanisms underlying phenotypic plasticity. In this study, we identified histone-modifying enzymes mediating histone post-translational modifications, which serve as a major regulatory mechanism of epigenetic processes, on the basis of the whole genome sequence of the migratory locust, Locusta migratoria. We confirmed the existence of various functional histone modifications in the locusts. Compared with other sequenced insect genomes, the locust genome contains a richer repertoire of histone-modifying enzymes. Several locust histone-modifying enzymes display vertebrate-like characteristics, such as the presence of a Sirt3-like gene and multiple alternative splicing of GCN5 gene. Most histone-modifying enzymes are highly expressed in the eggs or in the testis tissues of male adults. Several histone deacetylases and H3K4-specific methyltransferases exhibit differential expression patterns in brain tissues between solitarious and gregarious locusts. These results reveal the main characteristics of histone-modifying enzymes and provide important cues for understanding the epigenetic mechanisms underlying phase polyphenism in locusts.     

The Mechanics and Trajectory Control in Locust Jumping

Locusts (Locusta migratoria manilensis) are characterised by their flying ability and abiding jump ability. Research on the jumping mechanics and behavior of locusts plays an important role in elucidating the mechanism of hexapod locomotion. The jump gestures of locusts were observed using high-speed video camera at 250 fps. The reaction forces of the hindlegs were measured using two three-dimensional sensors, in case the two hindlegs attached on separated sensor plates. The jump gestures and reaction forces were used to illustrate the locust jumping mechanism. Results show that the trajectory control is achieved by rapid rolling and yawing movements of the locust body, caused by the forelegs, midlegs and hindlegs in different jumping phases. The final jump trajectory was not determined until hind tarsi left platform. The horizontal co-impulse between two hindlegs might play a key role in jump stability and accuracy. Besides, the angle between two hindlegs affects the control of jump trajectory but has a little effect on the elevation angle of a jump, which is controlled mechanically by the initial position of the hindlegs. This research lays the groundwork for the probable design and development of biomimetic robotics.