Fine structure and distribution of antennal sensilla of the desert locust, Schistocerca gregaria (Orthoptera: Acrididae)

The fine structure and distribution of various types of antennal sensilla in three nymphal stages and in adults of both solitary-reared (solitary) and crowd-reared (gregarious) phases of the desert locust, Schistocerca gregaria, were investigated by scanning and transmission electron microscopy. Four types of sensilla were identified: sensilla basiconica, s. trichodea, s. coeloconica and s. chaetica. S. basiconica contain up to 50 sensory neurons, each of which displays massive dendritic branching. The sensillar wall is penetrated by a large number of pores. In contrast, s. trichodea contain one to three sensory neurons that branch to give five or six dendrites in the sensillar lumen; the sensillum wall is penetrated by relatively few pores. The s. coeloconica are situated in spherical cuticular pits on the antennal surface. The s. coeloconica are of two types: one type contains one to three sensory neurons with double sensillar walls penetrated by slit-like pores, whereas the second type contains four sensory neurons with non-porous double sensillar walls. The s. chaetica have a flexible socket and a thick non-porous sensillum wall and contain four sensory neurons that send unbranched dendrites to a terminal pore. A fifth sensory neuron of the s. chaetica terminates in a tubular body at the base of the hair. S. basiconica and coeloconica are normally distributed over the entire antennal flagellum, with a concentration in the middle segments; s. trichodea have three areas of concentration on the 5th, 10th and 14th flagellar segments. Sensilla chaetica are most abundant on the terminal segment. Locusts raised in solitary conditions have more olfactory sensilla (s. basiconica and s. coeloconica) than crowd-reared locusts. The difference in sensillar numbers is more evident in adults than in nymphs. These results suggest that differences in the odour-mediated behaviour of nymphs and adults, and between the phases of S. gregaria, may be attributable to differences at the sensory input level.     

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。     

Fine structure and primary sensory projections of sensilla on the maxillary palp of Drosophila melanogaster Meigen (Diptera : Drosophilidae)

Three types of hairs were identified on the maxillary palp of Drosophila melanogaster Meigen (Diptera : Drosophilidae): (i) single-walled, multiporous sensilla basiconica, which constitute 75% of the innervated hairs; (ii) thick walled non-porous sensilla trichodea, which make up the remaining 25% of the innervated hairs; and (iii) numerous spinules, which are un-innervated. These sensilla basiconica uniformly contain 2 bipolar sense cells, whereas sensilla trichodea have a single dendrite with a tubular body at the base of each hair. A majority of the sensilla basiconica is located on the distal half of the dorsal surface, whereas sensilla trichodea are positioned on the tip and entire ventrolateral ridge of the palp. Approximately 125 axons of the sense cells join to form a single nerve. The structure of sensilla basiconica and sensilla trichodea suggests that they are olfactory and mechanosensory respectively. The contact chemoreceptors (gustatory sensilla) are conspicuously absent on the maxillary palp.Golgi silver impregnations and cobalt fills show that the primary sensory fibres from sensilla trichodea and sensilla basiconica on the maxillary palp project in the posterior suboesophageal ganglion (SOG) and the antennal lobe respectively. A single fibre projects separately either in the SOG or in the antennal lobe. In the antennal lobe, the input received from sensilla basiconica is usually bilateral and at least 5 glomeruli are innervated symmetrically on either side from both the palps.This study suggests that the sensory neurons are capable of making selective projections in the specific regions of the brain. Accordingly, the fibres from a sensillum project to the brain with respect to their functions and the individual glomeruli represent functional units of the brain, receiving inputs in a characteristic combination.     

Atlas of olfactory organs of Drosophila melanogaster: 1. Types,external organization,innervation and distribution of olfactory sensilla

The third antennal segment (funiculus) and the maxillary palp are the main and accessory olfactory sense organs of Drosophila melanogaster. Cryofixed antennae and palps revealed a superior preservation of the sensory dendrites and other cellular details as compared to conventional chemical fixation. Extensive cross-section series through funiculus and palp were studied in order to obtain as complete an evaluation as possible of the sensillar complement on these appendages. About 75% of all sensilla on the male and female funiculus were individually studied and their position on the antennal surface mapped. Dimensions of the cuticular apparatus of the various types of sensilla are provided as well as the number of innervating receptor neurons. Particular attention has been paid to the cuticular pores important for stimulus transport and to the sensory dendrites. On the funiculus surface, all sensilla have multiple wall pores: sensilla (s.) trichodea and s. basiconica are single-walled, s. coeloconica are double-walled. The distribution of s. trichodea and s. basiconica follows opposing gradients along a diagonal axis parallel to the axis of the arista from proximo-medial to disto-lateral. In this disto-lateral direction the density of s. trichodea increases while that of the s. basiconica decreases. S. trichodea occur in three subtypes with one, two or three receptor neurons. Basiconic sensilla can be subdivided into three subtypes of large s. basiconica (with two or four receptor neurons), three subtypes of thin s. basiconica (with mostly two, rarely four neurons), and one subtype of small s. basiconica with two receptor neurons. Large s. basiconica occur only in the most proximal region (the ‘LB-zone’); thin s. basiconica are most common in a belt that borders the LB-zone distally, while small s. basiconica are most numerous even further distally along the mentioned diagonal axis in between the s. trichodea. S. intermedia are single-walled, multiporous sensilla which combine features of s. trichodea and s. basiconica; they are found in two subtypes with two or three receptor neurons, in the same region where s. trichodea abound. The s. coeloconica are irregularly distributed over the funicular surface, and occur in two subtypes with two or three receptor neurons. Sexual dimorphism on the antenna is moderate, the female funiculus is a bit longer and carries a larger number of small s. basiconica and large s. basiconica of the LB-I subtype; the male funiculus, however, has more s. trichodea than the female. On the maxillary palp, besides mechanoreceptive s. chaetica, there are only s. basiconica with two receptor neurons. According to the fine structure of their sensory dendrites, three subtypes can be discriminated which are distributed in a random pattern. The functional significance of the described structures and distribution awaits future immunocytochemical and electrophysiological experiments.     

Morphology and distribution of sensilia on the cephalic appendages,tarsi and ovipositor of the European sunflower moth,Homoeosoma nebulella Den. & Schiff. (Lepidoptera : Pyralidae)

Sensilla on male and female antennae, mouthparts, tarsi and on the ovipositor of the European sunflower moth, Homoeosoma nebulella (Lepidoptera : Pyralidae) have been investigated by means of scanning electron microscope. The antennal flagellum bears multiporous sensilla (trichodea, basiconica, auricillica, coeloconica) and uniporous sensilla (chaetica, styloconica). A sexual dimorphism is found in the numbers of sensilla trichodea (8300 in males and 6000 in females) and sensilla basiconica (1150 in females and 650 in males). The proboscis has uniporous s. styloconica, multiporous s. basiconica (described for the first time in Lepidoptera), aporous s. chaetica, and some rare uniporous s. basiconica in the food channel. The labial palp-pit organ houses multiporous s. coeloconica, while the maxillary palps have aporous sensilla. Tarsi of both sexes possess one type of aporous s. chaetica and 2 types of uniporous s. chaetica. There is no significant difference in the distribution of tarsal sensilla between males and females. The surface of each lobe of the ovipositor is covered by 3 types of aporous s. trichodea of different lengths and about 60 multiporous s. basiconica, sensilla unusual on the ovipositor of Lepidoptera. The role of sensilla in the oviposition site selection is discussed.     

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。     

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.     

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。     

小菜蛾成虫喙管感器的超微结构及其神经元中枢投射

【目的】明确小菜蛾Plutella xylostella成虫喙管感器的形态结构及感器神经元的投射。【方法】利用扫描电子显微镜观察小菜蛾成虫喙管结构和感器,利用神经回填技术和激光共聚焦显微镜观察喙管感器神经元在脑部的投射。【结果】小菜蛾成虫喙管上存在毛形感器(两种亚型)、腔锥形感器、锥形感器、刺形感器和栓锥形感器5种不同类型的感器。毛形感器表面光滑,分布于外颚叶外侧,可分为毛形感器Ⅰ型和Ⅱ型两种亚型,其中Ⅰ型比Ⅱ型长;锥形感器分布于喙管外表面,由一个感觉锥和一个短的圆形基座组成;腔锥形感器仅分布于食管内侧,只有一个粗短感觉锥而无基座;刺形感器由一个细长的感觉毛和一个圆形基座组成,表面无孔,分布于喙管的外表面;栓锥形感器是昆虫喙管上最典型的感受器,集中分布于喙管顶端区域,感器顶部凹腔伸出一个单感觉锥。此外,喙管上的感觉和运动神经元投射到初级味觉中枢咽下神经节。【结论】本研究阐明了小菜蛾成虫喙管感器的类型、分布和形态特征及其感器神经元在脑部的投射形态,为深入了解小菜蛾喙管感器的生理和功能奠定了基础。     

Morphology and distribution of antennal sensilla of the tarnished plant bug,Lygus lineolaris (Palisot de beauvois) (Hemiptera: Miridae)

Sensilla on the antennae of adult and last-instar nymphs of the tarnished plant bug, Lygus lineolaris (Hemiptera: Miridae), were examined with light, scanning and transmission electron microscopy. Six different types were identified in adult females and males and 5 types in last-instar nymphs: types 1 and 4 are sensilla trichodea, 2 and 3 are sensilla chaetica, and 5 and 6 are sensilla basiconica. Type 1 are located at distal region of terminal segment and type 2 are located at distal regions of proximal 3 segments in both adults and nymphs. Type 3 is present on all segments, more numerous on scape and pedicel and less abundant on distal third and fourth segments in both adult and nymphal stages. Types 4 and 6 are absent on the scape and present on the distal 3 antennal segments in adults, but they are present only on the distal-most antennal segment in nymphs. Type 5 sensilla are present only on second antennal segments in adults and are absent in nymphs. Sexual dimorphism is observed in total numbers: there are significantly more type(s) 3, 4, 5 and 6 sensilla in adult males than adult females. Types 1, 4 and 5 are multiporous with thin cuticle, branched dendrites and pore tubules which suggests an olfactory function. These sensilla have 3, 3 and 2 neurons, respectively. The type 6 sensillum has an apical pore and pores in the cuticular wall, and is innervated by 5 nerve cells with unbranched dendrites. Sensillar types 2 and 3 have thick cuticle, a single apical pore and nerve cells with unbranched dendrites. Type 2 has 1 neuron and type 3 has 2 chambers and 2 nerve cells.     

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.     

Antennal sensilla of the ground beetle Bembidion lampros Hbst (Coleoptera, Carabidae)

Antennal sensilla typology, number and distribution pattern were studied in the ground beetle Bembidion lampros Hbst (Coleoptera, Carabidae) using scanning electron microscopy. The 1.6–1.8 mm long filiform antennae of both sexes consist of the scape, pedicel and of the flagellum composed of nine flagellomeres. In both sexes, three types of sensilla chaetica, two types of sensilla trichodea, five types of sensilla basiconica, one type of sensilla coeloconica, one type of sensilla campaniformia and Böhm sensilla were distinguished. The possible function of the sensilla was discussed and three types of sensilla were considered as olfactory, sensilla trichodea type 2 and sensilla basiconica types 1 and 2. Olfactory sensilla occupy dorsal and/or ventral areas of the flagellomeres and occur sparsely (sensilla basiconica type 1) or not at all (sensilla basiconica type 2 and sensilla trichodea type 2) outside these areas. No remarkable sexual differences in the types, numbers and distribution of antennal sensilla were found.     

Comparative study of sensilla and other tegumentary structures of Myrmeleontidae larvae (Insecta,Neuroptera)

Antlion larvae have a complex tegumentary sensorial equipment. The sensilla and other kinds of larval tegumentary structures have been studied in 29 species of 18 genera within family Myrmeleontidae, all of them with certain degree of psammophilous lifestyle. The adaptations for such lifestyle are probably related to the evolutionary success of this lineage within Neuroptera. We identified eight types of sensory structures, six types of sensilla (excluding typical long bristles) and two other specialized tegumentary structures. Both sensilla and other types of structures that have been observed using scanning electron microscopy show similar patterns in terms of occurrence and density in all the studied species (with few exceptions). The sensilla identified are: coeloconica, placoidea, basiconica, trichodea type I, trichodea type II, and campaniformia. All these sensilla have mechano- or chemosensorial functions. Some regions of the larval body have been studied using SEM for the first time, such as the surface of the food canal, which bears sensilla coeloconica, and the abdominal segment X, that bears three types of sensilla: coeloconica, basiconica, and campaniformia. Sensilla placodea are newly reported on antlion larvae, being present on the mandibular base, pronotum, mentum, and cardum. Also, new locations of sensilla coeloconica (e.g., on rastra) and sensilla campaniformia (e.g., on odontoid processes) are noted. A novel porous texture with chemoreceptor function has been identified in the base of mandibles. A mechanism of dentate-notched surfaces that anchor maxillae and mandible, reinforcing the food canal, is detailed. All these sensorial structures, in addition to ocular tubercles for light caption and their great muscular system, confer to these larvae an extraordinary predation capacity to success hunting and living in such harsh environments.     

拉步甲成虫触角感器的扫描电镜观察

利用扫描电子显微镜,观察了拉步甲Carabus lafossei成虫触角感器的类型、数量和分布规律。结果表明:拉步甲触角表面存在7类、12种感器类型,包括3种毛形感器(Sensilla trichodea,ST)、3种刺形感器(Sensilla chaetica,SCh)、2种锥形感器(Sensilla basiconca,SB)、Bhm氏鬃毛(Bhm bristles,BB)、腔锥形感器(Sensilla coeloconica,SCo)、腔形感器(Sensilla cavity,SCa)和钟形感器(Sensilla campaniformia,SCam),感器类型在雌、雄个体间无差异;雌、雄个体各节触角的感器数量和分布不均匀。研究结果为今后开展电生理学和行为生态学研究打下了基础。     

Ultrastructure of antennal sense organs of small ermine moths,Yponomeuta spp. (Lepidoptera : Yponomeutidae)

The ultrastructure of antennal sensilla was investigated in males and females of 5 European Yponomeuta species. Three types of olfactory sensilla could be distinguished, i.e. sensilla trichodea, sensilla basiconica, and sensilla coeloconica. Sexual dimorphism in the number of cells innervating sensilla trichodea could be established in 3 species. Most of these sensilla in males of Y. vigintipunctatus, Y. rorellus, and Y. cagnagellus are associated with 3 sensory cells, whereas in females of these species these sensilla contain 2 sensory cells. In both males and females of Y. padeltus and Y. malinellus, the great majority of the sensilla trichodea is innervated by 3 cells. So-called sensilla chaetica type 1 show features typical of a combined mechano/contact-chemoreceptor. No structures indicating a sensory function were found in sensilla chaetica type 11. Sensilla styloconica contain 3 cells, the dendritic outer segment of one being lamellated; most likely, these cells have a thermo- and hygroreceptive function. The findings concerning the olfactory sensilla are discussed in the context of olfactory communication and reproductive isolation in European Yponomeuta.     

Olfactory sensilla on the antennae of the pine weevil,Hylobius abietis

Summary Olfactory sensilla on the antennal club of the pine weevil, Hylobius abietis, have been studied by scanning and transmission electron microscopy. Two main types, sensilla basiconica and sensilla trichodea, have been classified. The former are found in two variants, one containing one sensory cell and the other two. Sensilla trichodea have one sensory cell. The two sensillum types are localized in different fields of the club. The numerous sensilla basiconica are confined exclusively to the two constriction bands. Sensilla trichodea, fewer in number, are mainly restricted to the distal part where they also form a third ring. In addition, they are found immediately distal to the two construction bands. The fine structure of the two types suggests an olfactory function which could be proven by electrophysiological studies. The other hairs on the club are shown to belong to mechano- and taste sensilla and uninnervated setae.I am grateful to the Norwegian Research Council for Science and Humanities NAVF and the Norwegian Forest Research Institute for financial support; to Professor D. Schneider for providing laboratory facilities at Seewiesen; to him and his colleagues, particularly Dr. R.A. Steinbrecht, for helpful discussions and to Miss Barbara Müller for electron microscopy assistance. I also wish to thank Dr. T. Braathen and his staff for help with scanning electron microscopy facilities at the University of Oslo.     

分月扇舟蛾触角感觉器的扫描电镜观察

利用扫描电镜对分月扇舟蛾Clostera anastomosis(L.)成虫触角感觉器的形态、结构进行了观察。扫描电镜观察结果表明,分月扇舟蛾触角由柄节、梗节和鞭节组成,触角外侧面覆盖有鳞片,绝大部分触角感觉器位于触角的腹面和外侧面。雌、雄蛾触角上均存在以下8种感觉器,即毛形感器、刺形感器、腔形感器、腔锥形感器、栓锥形感器、锥形感器、柱形感器和鳞形感器。各种感觉器在雌、雄蛾触角上的分布大体相同,但数量有明显的区别。     

Morphology and distribution of antennal sensilla in the pine wood nematode insect vectors Monochamus alternatus Hope and Monochamus saltuarius Gebler (Coleoptera: Cerambycidae)

As insect vectors of pine wood nematodes, Monochamus alternatus Hope and Monochamus saltuarius Gebler have different levels of attractiveness to semiochemicals. Although active use of chemical communication in both species is well known, there was no report on the differences in morphology and distribution of antennal sensilla between the two Monochamus species. The present study was carried out to explore the morphology, distribution, and ultrastructure of antennal sensilla of the two species using scanning and transmission electron microscopy. The overall shapes of the antennae were not different between M. alternatus and M. saltuarius. However, both M. alternatus and M. saltuarius exhibited sexual dimorphism overall. The antennae of each species were composed of the scape, pedicel, and nine flagellomeres, with four morphological types of sensilla: trichodea, basiconica, chaetica, and coeloconica. The four types occurred in varying numbers and distributions. The sensilla chaetica type was the most abundant in both species. Three types of sensilla (trichodea, basiconica, and chaetica) could be subdivided according to the two Monochamus species; sensilla trichodea could be divided into two subtypes, and sensilla basiconica and sensilla chaetica into three. All sensilla basiconica subtypes were multiporous, indicating that their primary function was olfactory. Sensilla trichodea subtype 2 was uniporous, indicating that the function of these sensilla might be gustatory. The morphological information obtained in our study provides a basis for future investigation of the sensory physiological function of each type of sensilla in the two species.     

Odorant response of individual sensilla on theDrosophila antenna

We have documented odor responses of all morphological classes of sensilla on the surface of theDrosophila antenna: sensilla basiconica, sensilla trichodea, and sensilla coeloconica. Both subtypes of s. basiconica, large and small, respond to odors. S. trichodea fall into different functional types. Type 1 appears narrowly tuned, as it responded only tocis-vaccenyl acetate, believed to be a pheromone. Type 2 responded totrans-2-hexenal and 4-methyl cyclohexanol. These two types of s. trichodea are differentially distributed on the antennal surface, and have dramatically different frequencies of spontaneous action potentials. Likewise, there are multiple types of s. coeloconica. One type is broadly tuned, responding most strongly to a test stimulus of butyric acid, but also to a variety of other odors; it is restricted to the dorso-medial portion of the third antennal segment. A second type gave detectable responses only totrans-2-hexenal. These results demonstrate that all classes of sensilla are olfactory, and they reveal the organizational complexity of theDrosophila olfactory system.