Ultrastructure of the antennal sensilla of the mayfly Baetis rhodani (Pictet) (Ephemeroptera : Baetidae)

The distribution and fine morphology of antennal sensilla of nymphal and adult mayfly, Baetis rhodani (Ephemeroptera : Baetidae), were examined. In the nymph, various kinds of sensilla (chaetica, basiconica, coeloconica and cuticular pits) are differently arranged on the antennal segments, whereas sensilla campaniformia delimit the distal border of the pedicel. A peculiar kind of sensillum basiconicum, named flat-tipped sensillum, is present along the entire antenna, even though in the flagellum it has a regular arrangement between the cuticular lobes that delimit the distal border of each article. In the subimago the scape and pedicel are profusely covered with microtrichia and scattered sensilla trichodea, whereas the flagellum shows cuticular ribs. Sensilla coeloconica are present along the ventral side of the flagellum. In the imago, the antenna is completely decorated with scales among which sensilla trichodea and sensilla coeloconica occasionally occur. As in the nymph, adult mayflies have a ring of sensilla campaniformia along the distal border of the pedicel. When compared with nymphal antennae, those of adults have fewer types of sensilla, presumably in relation to the short, non-feeding terrestrial life.     

Antennal sense organs of the cockroach, Leucophaea maderae

Adult and nymphal antennae of the cockroach, Leucophaea maderae, contain nine or more different morphological types of sense organs. There is no outwardly apparent sexual dimorphism in adult antennae. Nymphs are dificient in gross numbers of sensilla. Sense organs are classified morphologically by their similarity to known types of sensila and are assigned functions on this basis and preliminary electrophysiological data: Sensilla chaetica (A), thick-walled mechanoreceptive hairs in groups on the antennal base; S. chaetica (B), thick-walled setae which are tactile and probably chemoreceptive, occurring in the antennal base and flagellum; S. trichodea (A), thin-walled chemoreceptive hairs of the flagellum; S. trichodea (B), minute hairs on the scape and pedicel; S. basiconica, thin-walled chemoreceptive pegs, and S. coeloconica (?pit-pegs”?) of the flagellum; S. campaniformia and scolopidia, mechanoreceptors in the base and flagellum; plus Johnston's organ and/or connective chrodotonal organs in the pedicel. Calculations based on absolute counts of sensilla and their known innervation yield an estimate of about 3.3 × 10⁴ sensilla and 10⁵ cells per antenna.     

Comparison of sensory structures on the antenna of different species of Philopotamidae (Insecta: Trichoptera)

Structure and distribution of sensilla were studied in sixteen species of the caddisfly family Philopotamidae. Their antennae bear numerous curved trichoid and pseudoplacoid sensilla and fewer coronal, styloconic and chaetoid sensilla on the flagellar segments. The most numerous pseudoplacoid sensilla have non-specific localization. The curved trichoid sensilla form clusters ventrally on each antennal segment. Sensilla belonging to coronal, styloconic and chaetoid types have specific positions. Long grooved trichoid sensilla are located nonspecifically in all the studied species. The average number of sensilla per segment decreases from the proximal to distal part of the flagellum. Scapus and pedicellum are devoid of most types of sensilla, however, they bear the Böhm bristles and long trichoid sensilla. A positive correlation between antenna dimensions and its cuticular structures is found.     

Spatial organization of olfactory receptor neurons on the antenna of the cabbage looper moth

Electrophysiological responses to stimulation with behaviorally relevant compounds were recorded from receptor neurons within specialized classes of sensilla on the antennae of male cabbage looper moths. Receptor neurons were found that specifically respond to stimulation with Z-7,12:AC, Z-7,14:AC, Z-9,14:AC, and Z-7,12:OH. Specialized receptor neurons were not found for the three remaining pheromone blend components, 12:AC, Z-5,12:AC, or 11,12:AC. However, a new class of sensillum containing a pair of neurons insensitive to all of the cabbage looper pheromone components was encountered. In addition, spatial patterns of distribution along the flagellum for identified classes of sensilla are described. Sensilla containing Z-7,12:AC-sensitive neurons are preferentially located on the proximal half of the antennal flagellum. In addition to this distribution along the length of the antenna, a pattern across individual flagellar subsegments is described. Sensilla containing neurons sensitive to Z-9,14:AC were found exclusively on the lateral margins of individual flagellar subsegments. Accepted: 19 June 1998     

Sense organs on the antennal flagellum of the green stink bug,Nezara viridula (L.) (Heteroptera : Pentatomidae): Sensillum types and numerical growth during the post-embryonic development

The sensilla on the antennal flagellum of Nezara viridula (Heteroptera : Pentatomidae) were studied with the scanning and transmission electron microscopes. Seven morphologically distinct types of sensilla were identified in adults. The number and distribution of six types were studied. Male and female antennae bear the same numbers and types of sensilla. As in other Heteroptera, the flagellum comprises two segments. The second flagellar segment bears more sensilla than the first segment. Sensilla are evenly distributed over the flagellum surface. The total number of sensilla increases during the post-embryonic development. Individual numerical growths of each type follow simple exponential laws when expressed as functions of developmental stage. The growth in number shows positive allometry in respect to body size for sensillum types 1, 2 + 5 and 4, but negative allometry for types 3 and 6. The density of sensilla remains constant. These findings are compared with previously published data from other heterometabolous insects. Adaptation to the increase in body size during the post-embryonic development seems to be the main determinant of the growth of the olfactory system in N. viridula.     

越北腹露蝗触角感器的扫描电镜观察

应用环境扫描电镜(ESEM)对越北腹露蝗FruhstorferiolatonkinensisWill.触角的外部形态进行观察的结果表明,蝗蝻和成虫触角均分布有以下6种感器,毛形感器、刺形感器、锥形感器、栓锥形感器、腔锥形感器和Bhm氏鬃毛,其中锥形感器有长、短锥之分,腔锥形感器有Ⅰ、Ⅱ型之分。芽孢形感器、盾形感器和钟形感器只限于蝗蝻的触角。成虫触角鞭节末端长锥形感器数量多于蝗蝻;而蝗蝻触角鞭节末端短锥形感器数量多于成虫。成虫触角从第9节开始,蝗蝻触角从第11节开始锥形感器和腔锥形感器的数量明显增多。     

烟盲蝽成虫触角感器的扫描电镜观察

烟盲蝽Nesidiocoris tenuis(Reuter)作为一种杂食性昆虫,是蔬菜害虫的重要捕食者。利用扫描电镜对烟盲蝽雌雄成虫的触角进行观察,结果表明:烟盲蝽触角由基节、柄节、梗节和鞭节组成。绝大部分触角感器位于触角的腹面和外侧面。触角感器共有9种,分别为毛形感器、刺形感器、锥形感器、钟形感器、腔锥形感器、具弯钩形感器、腔形感器、乳形感器和Bhm氏鬃毛。腔锥形感器仅见于雌性触角,其他8种感器在雌雄两性触角上的类型和分布没有明显的区别。     

Differentiation of insect sensory neurons in the absence of their normal synaptic targets.

Sensory neurons in the antenna of the moth, Manduca sexta, arise and differentiate during the 18 days of metamorphosis from pupa to adult, sending axons to the brain. To assess the trophic dependence of developing antennal neurons on their targets, we studied antennae from surgically debrained animals. If the brain is removed 1 to 45 hr after pupal ecdysis (before and during the period when antennal neurons arise by cell divisions), adult development can be triggered by injection of β-ecdysone; if the brain is removed 50 to 60 hr after pupal ecdysis (before antennal axons contact the brain), metamorphosis proceeds spontaneously. Neurons proliferate normally and differentiate extensively in the antennae of debrained animals. They acquire a characteristic size and shape, elaborate axons and dendrites, migrate to appropriate positions in the sensilla, accumulate components of a neurotransmitter system (acetylcholine, choline acetyltransferase, and acetylcholinesterase), and generate electrical responses to olfactory and mechanical stimuli. Antennal sensory neurons thus differ from a variety of vertebrate neurons, which fail to mature when deprived of their synaptic targets.     

Sensilla of the antennae and the labial and maxillary palps of Blattella germanica (L.) (Dictyoptera: Blattellidae): Their classification and distribution

The various sensilla on the antennae and on the labial and maxillary palps of Blattella germanica (L.) were studied. Thick-walled chemoreceptors with fluted shafts and articulated bases are located on the antennae and on the labial and maxillary palps. Thin-walled chemoreceptors, without fluted shafts or articulated bases, are restricted to the flagellar segments of the antennae and to the distal segments of the palps. Antennae of adult males have more thin-walled chemoreceptors than do those of females. Hair-plate sensilla are found at the scape-head and scape-pedicel joints, and at the joints of segments on the palps. Campaniform sensilla are concentrated as a ring around the distal margin of the pedicel, and are also scattered singly on the scape, pedicel, and flagellar segments of the antennae, and on the first segment of the maxillary palps. Occasionally, a few sensilla coeloconica and cold receptor sensilla are found on the antennal flagellum.     

斑鞘豆叶甲触角感器的超微结构

斑鞘豆叶甲是大豆苗期重要害虫,本文利用扫描电镜技术观察了斑鞘豆叶甲触角感器超微形态与分布。结果表明:斑鞘豆叶甲触角感器绝大部分着生于鞭节,在鞭亚节端部和末节凹陷区感器分布密集,类型较多。基于感器外部形态可分为8种类型:毛形感器Ⅰ型和Ⅱ型、刺形感器、锥形感器、指形感器、腔锥形感器、栓锥形感器Ⅰ型和Ⅱ型、钟形感器和B hm氏鬃毛。其中毛形感器数量最多,其次是锥形感器,钟形感器最少,仅分布于雄虫触角,还着生有大量表皮孔。雌、雄虫触角感器在形态、数量和分布上均存在差异,雄虫毛形和刺形感器显著长于雌虫,刺形感器端部膨大,两种感器的数量也明显多于雌虫;雌虫与雄虫相比末节背面也具感器密集的凹陷区,指形感器短于雄虫但数量显著多于雄虫。斑鞘豆叶甲触角感器种类丰富,分布密集,雌、雄虫感器存在明显的性二型现象,其结构和类型表现出种间分化特性。     

Changes in distribution and abundance of antennal sensilla during growth of Locusta migratoria L. (Orthoptera : Acrididae)

The antenna of Locusta migratoria (Orthoptera : Acrididae) increases in length by the production of new annuli proximally and by elongation of existing annuli. The most distal annuli are fully differentiated at the time of hatching and no new olfactory sensilla are added to them at subsequent molts. More proximally, the differentiation of trichoid contact chemoreceptors precedes the development of olfactory sensilla. Sensillum differentiation proceeds from distal to proximal along the antenna and more distal annuli attain full development at each molt. The biggest increase in numbers of olfactory sensilla occurs at the final molt. On any one annulus, most olfactory sensilla are restricted to sensory fields on the anterior and posterior faces. Their spacing within these fields is consistent with the existence of separate but interacting chaetogens regulating the differentiation of basiconic and coeloconic sensilla.     

Sex-specific antennal sensory system in the ant <Emphasis Type="Italic">Camponotus japonicus</Emphasis>: structure and distribution of sensilla on the flagellum

The antennae are a critically important component of the ant’s highly elaborated chemical communication systems. However, our understanding of the organization of the sensory systems on the antennae of ants, from peripheral receptors to central and output systems, is poorly understood. Consequently, we have used scanning electron and confocal laser microscopy to create virtually complete maps of the structure, numbers of sensory neurons, and distribution patterns of all types of external sensilla on the antennal flagellum of all types of colony members of the carpenter ant Camponotus japonicus. Based on the outer cuticular structures, the sensilla have been classified into seven types: coelocapitular, coeloconic, ampullaceal, basiconic, trichoid-I, trichoid-II, and chaetic sensilla. Retrograde staining of antennal nerves has enabled us to count the number of sensory neurons housed in the different types of sensilla: three in a coelocapitular sensillum, three in a coeloconic sensillum, one in an ampullaceal sensillum, over 130 in a basiconic sensillum, 50–60 in a trichoid-I sensillum, and 8–9 in a trichoid-II sensillum. The basiconic sensilla, which are cuticular hydrocarbon-receptive in the ant, are present in workers and unmated queens but absent in males. Coelocapitular sensilla (putatively hygro- and thermoreceptive) have been newly identified in this study. Coelocapitular, coeloconic, and ampullaceal sensilla form clusters and show biased distributions on flagellar segments of antennae in all colony members. The total numbers of sensilla per flagellum are about 9000 in unmated queens, 7500 in workers, and 6000 in males. This is the first report presenting comprehensive sensillar maps of antennae in ants.     

Identification of serotonin- and vasopressin immunoreactivities in the suprachiasmatic nucleus of four mammalian species

Summary Cobalt fills from small, defined regions of the antenna in D. melanogaster show that the three types of sensilla on the third segment, the flagellum, and a fourth sensillum located in the arista, project into the glomeruli of the antennal lobe. We have identified 19 glomeruli in each lobe, according to their location, shape, and size. At least ten of these represent major projection areas of flagellar or aristal sensilla. The large majority of glomeruli is innervated from both antennae, but a small group of five receive exclusively ipsilateral input. A particular sensory fiber appears to terminate only in one specific glomerulus, either in the ipsilateral or in both lobes. Fills from flagellar regions bearing a single type of sensillum, yield a specific pattern of glomeruli containing stained terminals. Aristal projections remain strictly ipsilateral, whereas those from the other sensilla consist of an ipsilateral and a bilateral component. When filling from different points in an area bearing one type of sensillum, similar projections are produced, suggesting that projection patterns observed reflect predominantly the type of sensillum rather than its location on the flagellum. Accordingly, individual glomeruli might represent functional units, each receiving antennal input in a characteristic combination.We are indebted to Dr. H. Tobler for critical comments. R.F.S. was supported by the Swiss National Foundation (Grant No. 3.541-0.79) as well as a Travel Aid by the Swiss Academy of Sciences     

Electrophysiological identification of thermo- and hygro-sensitive receptor neurons on the antennae of the dragonfly Libellula depressa

Recent ultrastructural investigations on Odonata antennal flagellum describe two types of sensilla styloconica, T1 and T2. The styloconic sensilla are located in pits, at the bottom of deep cavities, and share common features typical of thermo-hygroreceptors. In order to ascertain if the Odonata antennae are involved in hygroreception and thermoreception, we carried out electrophysiological recordings (single cell recordings, SCR) from adult males and females of Libellula depressa L., 1758. After contact was established, the antenna was stimulated by rapid changes in temperature and humidity. The present research shows the occurrence of a dry (DC), a moist (MC) and a cold (CC) receptor neurons on the antennal flagellum of L. depressa. These data demonstrate for the first time the presence of functional thermo-hygroreceptors on the antennal flagellum of dragonflies. The present results extend our knowledge of the not visual sensory modalities of Odonata, a field of research unexplored so far.     

Antennal sensilla and their possible functions in the host-plant selection behaviour of Phenacoccus manihoti (Matile-Ferrero) (Homoptera : Pseudococcidae)

Nine different types of sensilla have been identified on the antenna of the cassava mealybug Phenacoccus manihoti (Homoptera : Pseudococcidae) with scanning and transmission electron microscopes. Trichoid sensilla, distributed on all segments of the antenna and innervated by a single mechanoreceptive dendrite, have the characteristics of exteroceptors. A campaniform sensillum located on the pedicel and one basiconic sensillum on the flagellum have the characteristics of proprioceptors. Coeloconic sensilla, located ventrally on the pedicel and flagellum, related to poreless sensilla with inflexible sockets, have the characteristics of thermo/hygroreceptors. Uniporous sensilla with a mechanoreceptive dendrite (smooth pegs P1 and P2, grooved pegs P3) and multiporous chemosensilla (grooved pegs P4 and P5), present on the tip of the flagellum, have, respectively, the characteristics of gustatory and olfactory receptors. The results of this study seem to suggest that the cassava mealybug has sensory equipment on its antennae that can detect, by olfaction and contact, chemicals released by the plant.     

疟疾媒介中华按蚊触角感器的扫描电镜观察

【目的】明确中华按蚊Anopheles sinensis雌成虫与幼虫触角感器的类型、形态和分布。【方法】利用光学显微镜观察中华按蚊成虫与幼虫触角的形态结构,利用扫描电镜观察触角上的感器类型、形态和分布。【结果】中华按蚊雌成虫触角由柄节、梗节和鞭节组成,鞭节有13个亚节。触角上共发现4种类型的感器,分别为毛形感器(锐型和钝型)、刺形感器(大型和小型)、锥形感器(Ⅰ型和Ⅱ型)和腔锥形感器(大型和小型)。雌成虫触角各类感器总计约1 135.67±86.75个,其中毛形感器数量最多(662.00±6.22个),随后是刺形感器(294.67±33.35个)和锥形感器(146.00±42.39个),腔锥形感器数量最少(36.50±5.90个)。毛形感器、刺形感器和锥形感器在鞭节的每个亚节均有分布,而大型腔锥形感器在第9-11亚节没有分布,小型腔锥形感器仅分布于第13节的顶端。幼虫触角的鞭节不分亚节,呈管状,触角末端有一个感觉锥,鞭节上分布有与成虫锥形感器相似的锥形凸起,初步定名为类锥形感器,其数量和大小随幼虫龄期的增长而显著增加,锥体表面的凹槽越来越明显,其功能还需要通过超微结构和电生理等研究进一步确定。【结论】本研究对中华按蚊幼虫和雌成虫触角感器的形态特征、类型、数量及其分布进行了观察和分析,结果为进一步研究中华按蚊感器的生理功能奠定了基础。     

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。     

桑天牛头部附器感器的扫描电镜观察

利用扫描电镜观测桑天牛Apriona germari(Hope)成虫的触角、下颚须和下唇须上感器的分布及超微结构。结果表明,雌、雄桑天牛触角上共存在6种感器,即毛形感器、锥形感器、刺形感器、芽形感器、鳞形感器和棒形感器,其中锥形感器分5种亚型,刺形感器分2种亚型,且部分感器在雌雄成虫触角上的分布模式及数量存在差异,如棒形感器及角锥形感器丛模式仅在雄虫触角上发现,而雌虫触角上的细锥形感器和耳锥形感器多于雄虫,芽形感器少于雄虫;下颚须和下唇须存在5种感器,即毛形感器、刺形感器、末梢锥形感器、钟形感器和隙缝感器,各种感器在雌、雄天牛下颚须和下唇须上的分布和数量无明显的区别。     

Morphology and distribution of antennal sense organs and diversity of mouthpart structures in Odontopus nigricornis (Stall) and Nezara viridula L. (Hemiptera)

Sensilla on the antennae and labial tip of the adult hemipteran bugs, Odontopus nigricornis Stall (Pyrrhocoridae) and Nezara viridula L. (Pentatomidae) (Hemiptera) were examined with an electron microscope in order to study their morphology, distribution, and possible chemo- and mechanoreceptive functions for food detection. The antenna contains 2 types of sensilla trichodea and 3 types of sensilla basiconica on the flagellar segments. S. trichodea are most abundant in both insects. Long slender hairs with elevated bases, and slightly shorter hairs with flexible sockets at the bases are common in both species. However, on each antennal segment of O.nigricornis, 1 or 2 rows of very long trichodeal hairs with longitudinal grooves and blunt tips are visible. At the periphery, S. basiconica with bulbous bases were also observed in addition to sensilla chaetica. The tripartite apex of the labium in both species consists of 2 lateral lobes and an apical plate. Each lateral lobe possesses a field of 11 thick-walled uniporous peg sensilla and long non-porous hair sensilla. Mandibular stylets of O.nigricornis have barbs, which may help in penetrating the hard seed coat. These insects made circular holes while feeding on the seed. A possible mechanism of feeding is discussed.