Olfactory sensilla on the antenna and maxillary palp of the sheep head fly,Hydrotaea irritans (Fallen) (Diptera : Muscidae)

Antennae and maxillary palps of both sexes of the Sheep Head fly Hydrotaea irritans (Diptera : Muscidae) were investigated using scanning electron microscopy to describe the types, morphology, and distribution of olfactory sensory structures. Only socketed bristles and microtrichia were found on the scape of the antennae. These structures were also observed on the pedicel together with a group of 7–8 as yet undescribed sensilla, whose function is unknown. Olfactory sensilla were not found on these 2 segments or on the arista. Large numbers of olfactory sensilla and microtrichia were present on the funiculus. The former included sensilla trichodea (thick-walled, multiporous sensilla), sensilla styloconica and 6 types of sensilla basiconica (thin-walled, multiporous sensilla), 4 of which occurred individually and 2 of which were found in groups. An olfactory pit containing groups of thin-walled multiporous sensilla was located on the dorsomedian side of the funiculus. All sensilla basiconica were classified on morphological characteristics. The maxillary palps were covered with microtrichia and socketed bristles, but only 1 type of olfactory sensillum was found. This was a type of sensillum basiconicum that differed from any of those found on the antennae. No differences were found in sensilla diversity and distribution between males and females.     

Cuticular structures on the antennae of Hypoderma bovis De Geer (Diptera : Oestridae) females

The antennae of Hypoderma bovis (Diptera: Oestridae) females were examined using scanning electron microscopy. Each antenna is composed of 3 parts: the scape, the pedicel, and the funiculus, with a large, protruding arista. Mechanoreceptors are found on the proximal and lateral margins of the scape and pedicel, respectively. Microtrichia, which are presumably non-innervated, are located evenly over both the outer surface of the scape and the inner surface of the pedicel. A narrow band of microtrichia is present proximally on the outer surface of the pedicel. The entire funicular surface is densely covered with microtrichia. Small patches lacking these microtrichia appear as depressions or “pits” (8–20 μm in diameter) on the surface of the funiculus. Olfactory sensilla found on the funicular surface include basiconica type 1, basiconica type 2, and trichoid sensilla. The sensilla basiconica commonly occur in pits on the anterodorsal surface of the funiculus. Trichoid sensilla are abundant on the posteroventral surface of the funiculus and do not appear to occur in pits. In addition, clavate and peg sensilla, whose functions are unknown, are found in low numbers on the funicular surface. There may be as many as 300 olfactory pits on the anterodorsal surface of each funiculus. These are single-chambered and contain 6 or fewer sensilla basiconica. We propose that a relatively high number of pits may be characteristic of flies in Superfamily Oestroidea (as compared with those of Superfamily Muscoidea), but that pit morphology within the Calyptratae is not Superfamily-specific.     

Description of the antennal sensilla of <Emphasis Type="Italic">Habrobracon Hebetor</Emphasis>

The morphology of the antennal sensilla of both male and female Habrobracon hebetor (Say) (Hymenoptera: Braconidae) is described using Scanning Electron Microscopy complemented with Transmission Electron Microscopy. Five types of innervated sensilla as well as uninnervated microtrichia were found. These types are: sensilla trichodea; s. chaetica; s. basiconica; s. coeloconica; and s. placodea. No differences in shape, basic structure, and types of antennal sensilla were found between males and females. The types of sensilla of both sexes of H. hebetor were compared with what has been described in other parasitic Hymenoptera, and their putative functions are discussed with reference to their morphology, distribution and ultrastructure.     

小菜蛾成虫下唇须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成虫下唇须感器的形态结构及感器神经元的投射。【方法】利用光学显微镜观察和扫描电子显微镜观察下唇须结构和感器类型,利用神经回填技术和激光共聚焦显微镜观察下唇须感器神经元在脑部的投射。【结果】小菜蛾成虫下唇须共3节,其上存在Böhm氏鬃毛、钟形感器、鳞形感器、锥形感器、微毛形感器5种不同类型的感器和一个陷窝器结构。Böhm氏鬃毛短小尖细,钟形感器形如顶部凹陷的圆帽,两种感器均分布于下唇须第1节,且大小上均无雌雄二型差异;鳞形感器形同柳叶,锥形感器粗而直,均散生于下唇须的第2和3节,两种感器在大小上均存在雌雄二型差异,其中雌性的鳞形感器显著大于雄性的,根据其雌雄二型差异现象推测雌蛾的鳞形感器可能与感受寄主植物挥发物有关;下唇须第3节中上部具有一个圆形陷窝器结构,雄虫的陷窝器内径为5.68±0.33μm,雌虫的为6.03±0.23μm,雌雄间无显著性差异;凹坑内长有表面光滑的微毛形感器。小菜蛾下唇须感器神经元主要投射于脑部咽下神经节、每个触角叶的下唇须陷窝器神经纤维球和腹神经索3条通路。【结论】阐明了小菜蛾下唇须感器的类型、分布和形态特征及其感器神经元在脑部的投射形态,为深入了解小菜蛾下唇须感器的生理和功能奠定了基础。     

Sensilla of Carabus (Isiocarabus) fiduciarius saishutoicus Csiki (Coleoptera : Carabidae)

Sensilla on the antenna of the ground beetle, Carabus (Isiocarabus) fiduciarius saishutoicus Csiki (Coleoptera: Carabidae), were investigated using scanning electron microscopy. In both sexes, 5 types of sensilla trichodea, 7 types of sensilla basiconica, 1 type of sensilla ampullacea, and 2 types of sensilla campaniformia are distinguished. No sexual differences in the types and distribution of sensilla are found on the antenna, except a ventral, depressed, hairless region of the male. Various types of sensilla present on the mouthparts, head, pronotum, elytron, hindwing, legs, abdominal tergites and sternites, aedeagus, and ovipositor are also described.     

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.     

External morphology of antennal sensilla of four species of adult flea beetles (Coleoptera : chrysomelidae : alticinae)

External morphology of antennal sensilla of both sexes of Phyllotetra cruciferae (Goeze) and Psylloides punctulata Melsh, both of which feed on the mustard family Cruciferae, and Epitrix cucumeris (Harris) and Psylloides affinis (Paykell), both of which feed on the nightshade family Solanaceae, was studied using scanning electron microscopy. All belong to Alticinae (Coleoptera : Chrysomelidae). The number and distribution of antennal sensilla were also determined. Eight types of sensilla could be distinguished on the flagella of the species examined: sensilla chaetica; sensilla trichodea I and II; long sensilla basiconica I and II; and short sensilla basiconica I, II and III. The sensilla chaetica are probable tactile mechanosensilla, whereas both types of sensilla trichodea and long sensilla basiconica likely function in olfaction. Suggested functions for the short sensilla basiconica I, II and III include hygro-/thermoreception and chemoreception.The lack of sexual dimorphism in antennal structure and in types as well as number of sensilla, indicates that the sensilla probably have similar functions in both sexes. Probably most of the antennal olfactory sensilla are involved in host location and recognition. Any correlation between number of a particular type of sensillum or total number of all types and general host preference is not apparent.     

Antennal sensilla of the click beetle,limonius aeruginosus (OLIVIER) (COLEOPTERA: ELATERIDAE)

Antennal sensilla typology, number and distribution of the click beetle Limonius aeruginosus (Olivier) (Coleoptera: Elateridae) were studied using scanning electron microscopy. The serrate antennae of both sexes of L. aeruginosus consist of the scape, pedicel and of the flagellum which is composed of 9 flagellomeres. In both sexes, 5 types of sensilla basiconica, 1 type of sensilla trichodea, 1 type of sensilla chaetica, 1 type of sensilla campaniformia and Böhm sensilla were distinguished. No remarkable sexual differences in the types, numbers and distribution of sensilla were found on the antennae, except for the sensilla basiconica type II. The average number of sensilla basiconica type II on the antennae of the male beetle surpassed that on the antennae of the female beetle (3562 and 108 pegs, respectively). It is suggested that this type of sensilla on the male beetles antennae is responsible for the reception of the sex pheromone produced by the female beetle.     

Morphometry and distribution of sensilla on the antennae of Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae)

Antennal sensilla of Anastrepha fraterculus (Wied.) were examined using scanning electron microscopy. In the flagellum, there are trichoid, basiconic, clavate type I and II, and styloconic sensilla and microtrichia. Only microtrichiae and chaetica sensilla were observed in the scape and pedicel. The number of sensilla in the flagellum was similar between sexes. At the apex there was a higher density of trichoid and an absence of clavate sensilla, while basiconic sensilla were more abundant in the proximal region.     

Antennal sensilla and sexual dimorphism of the adult ladybird beetle Semiadalia undecimnotata Schn. (Coleoptera: Coccinellidae)

The antennal receptors of the adult male and female ladybird beetle, Semiadalia undecimnotata (Coleoptera: Coccinellidae), were examined by scanning and transmission electron microscopy. Twelve types of receptors were characterized and grouped into 5 morphological classes: Böhm, trichoid, coeloconic, basiconic, and chetiform sensilla. Sensory function was determined on the basis of sensillar ultrastructure and electrophysiological response. Olfactory sensilla are confined in both sexes to the 2 terminal antennal segments. In contrast, gustatory and mechanosensitive organs are present along the entire length of the antennae. Sexual dimorphism of antennal receptors is limited to the latter 2 functional classes. The principal characteristics of this dimorphism are the following: a) males possess 540 sensilla (all types), while females possess only 500; b) males exhibit 2 types of taste receptors not present in females; c) females exhibit one type of mechanoreceptor absent in males; d) the 3 sex-specific types of sensilla, which occupy the same position in males and females, are confined to the inner side of the antennae. The possible role of male-specific sensilla in intersexual communication is discussed.     

Antennal sensilla of whiteflies: Trialeurodes vaporariorum (Westwood), the glasshouse whitefly,Aleyrodes proletella (Linnaeus), the cabbage whitefly,and Bemisia tabaci (Gennadius), the tobacco whitefly (Homoptera : Aleyrodidae). Part 1: External morphology

Scanning electron microscopy has revealed the detailed structure of the antennae of three species of whitefly, Trialeurodes vaporariorum, Aleyrodes proletella, and Bemisia tabaci (Homoptera : Aleyrodidae). All 3 species have microtrichia and 5 types of sensilla on the antennae: chaetica, campaniform, basiconic, coeloconic, and pegs with digitate tips, the latter 3 of these being unique to the flagellum. The number and distribution of the sensilla unique to the flagellum vary among the species studied. The cuticle of the basiconic and the coeloconic sensilla is pitted and grooved, respectively, a prerequisite for an olfactory and/or a thermo-, hygroreceptive function. A sexual dimorphism does occur with respect to the position of the basiconic sensilla on flagella segment 5 of A. proletella, but not T. vaporariorum or B. tabaci.     

Ultrastructure of the antennal sensilla of Alabama argillacea (Hübner, 1823) (Lepidoptera: Erebidae)

Insects have several types of sensilla, the characterization of which has been fundamental to understanding the mechanisms of sensory perception in different species. This study aimed to describe the ultrastructure of the sensilla present on the antennae of Alabama argillacea (Hübner, 1823) (Lepidoptera: Erebidae), an important pest of cotton (Gossypium hirsutum L.) crops, as well as their possible variation between sexes. To do this, the antennae of males and females of A. argillacea were analyzed using scanning electron microscopy. Sensilla morphometry was assessed using photomicrographs, from which the lengths and basal and apical diameters of sensilla were measured using the ImageJ program. Seven types of sensilla were identified on the antennae of A. argillacea: sensilla trichodea, sensilla chaetica, sensilla auricillica, sensilla coeloconica, sensilla styloconica, sensilla basiconica, and sensilla Böhm bristles. Differences between the sensilla of males and females were found in their lengths and basal diameters in the distal and proximal regions. This suggests that sensilla functionality may not only vary from one species to another, but also between sexes within the same species. Thus, further transmission electron microscopy and single sensillum recording studies may provide more detailed information on the sensilla of A. argillacea and their functions.     

Morphological and ultrastructural characterization of olfactory sensilla in Drosophila suzukii: Scanning and transmission electron microscopy

Drosophila suzukii is a serious horticultural and quarantine pest, damaging various berry crops. Although the active use of olfactory communication in D. suzukii is well-known, their olfactory sensory system has not been comprehensively reported. Therefore, the present study was carried out to understand the morphology, distribution and ultrastructure of olfactory sensilla present in the antennae and maxillary palps of D. suzukii, through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The olfactory sensilla on the antennae of D. suzukii in both sexes could be classified into three major morphological types, basiconic, trichoid and coeloconic sensilla, according to their shapes. The antennal basiconic sensilla were further divided into three subtypes and the antennal trichoid sensilla into two subtypes, respectively, according to the size of individual sensillum. In contrast to the antennal olfactory sensilla showing diverse morphology, basiconic sensilla was the only type of olfactory sensilla in the maxillary palps of D. suzukii. The basiconic sensilla in the maxillary palps could be further classified into three subtypes, based on their size. Our SEM and TEM observations indicated that multiple nanoscale pores are present on the surface of all types of olfactory sensilla in the antennae and maxillary palps, except coeloconic sensilla. The difference in the morphological types and the distribution of olfactory sensilla suggests that their olfactory functions are different between antennae and maxillary palps in D. suzukii. The results of this study provide useful information for further studies to determine the function of olfactory sensilla in D. suzukii and to understand their chemical communication system.     

Sensilla on the antennal funiculus of the horse stomach bot fly, Gasterophilus nigricornis

Gasterophilus nigricornis (Loew) (Diptera: Oestridae) is one of the most damaging obligate parasites of equids in Kalamaili, Xinjiang, China. The main olfactory organs of this stomach bot fly are paired antennae that bear microscopic sensillar structures. The external morphology of the antennal funiculus and sensilla of male G. nigricornis were studied using stereopic microscopy and scanning electron microscopy. A cross-sectional view of the funiculus shows it to be triangular, with an anterodorsal surface, a dorsolateral margin and a posteroventral surface. Almost the entire surface of the funiculus is densely covered with microtrichiae. Small patches lacking these microtrichiae appear as depressions or pits in the surface of the funiculus. Six distinct types of sensilla are recorded, including one trichoid, three basiconic, one auriculate and one clavate sensilla. Trichoid sensilla are the most abundant, followed by the basiconic, auriculate and clavate types in descending order. Only auriculate sensilla are found in pits on the funiculus. Distributions of different sensilla types located on the antennal funiculus are provided. These results are compared with equivalent findings in several other fly species. In addition, the possible functions of the various sensilla types are discussed.     

三种粉虱触角、口针及跗节感受器的超微结构观察

对烟粉虱Bemisia tabaci、温室白粉虱Trialeurodes vaporariorum和禾粉虱Aleurocybotus indicus3种粉虱的触角、口针及跗节感受器的超微结构进行了观察。利用扫描电镜观察了烟粉虱、温室白粉虱和禾粉虱3种粉虱触角、口针及跗节化学感受器的类型和分布,进行了比较。3种粉虱触角上都有刚毛感受器、锥形感受器2种感受器和微毛,烟粉虱触角还有钟形感受器和腔锥感受器;温室白粉虱和禾粉虱触角均没有发现钟形感受器;3种粉虱的口针和跗节上均只有刚毛感受器和微毛,且形态结构相似。     

Morphology of the antennal sensilla of the cabbage root fly,Delia radicum L. (Diptera : Anthomyiidae)

The antennal sensilla of Delia radicum L. (Diptera : Anthomyiidae) were studied by scanning electron microscopy. On the scape and pedicel, grooved socketed bristles and setiferous plaques were found. There are 4 types of surface sensilla on the funicle: trichoid, basiconic, clavate, and grooved. Their numbers and distribution are described. There are 3–4 single-chambered pits on the dorsal surface of the funicle of both sexes and these contain basiconic sensilla. On the ventral surface, there is one multi-chambered pit, which contains 5 types of sensilla: grooved s., smooth-walled conical s., smooth-walled tapered s., striated s. and a novel type, flattened sensilla. These results are compared with previously published studies on several other fly species.     

Antennal sensilla in adult Agathiphaga vitiensis dumbl. and A. queenslandensis dumbl. (Lepidoptera : Agathiphagidae)

The antennae of both sexes of Agathiphaga vitiensis and the antenna of the female of A. queenslandensis (Lepidoptera : Agathiphagidae) were studied with a scanning electron microscope. In both sexes, 10 types of sensilla were observed on the antennae of A. vitiensis: Böhm's bristles, chaetica (types I and II), squamiformia, trichodea, biforked basiconica, short basiconica and coeloconica (types I, II and III). The female of A. queenslandensis possesses the same types of sensilla, except that the biforked basiconica are flattened. Biforked sensillum basiconicum is being reported in Lepidoptera for the first time. Their presence supports Kristensen's hypothesis on the phylogeny of Lepidoptera (1984). The female of A. vitiensis possesses more sensilla than that of A. queenslandensis. The male of A. vitiensis has a greater number of s. trichodea than the female, but the biforked sensilla basiconica are more numerous on the female antenna than on the male one.     

Scanning Electron Microscopy Studies of the Antennal Sensilla of Metaphycus parasaissetiae Zhang & Huang (Hymenoptera: Encyrtidae)

Metaphycus parasaissetiae Zhang & Huang (Hymenoptera: Encyrtidae) is an important adult parasitoid of Parasaissetia nigra Nietner (Hemiptera: Coccoidea). The external morphology of the antennal sensilla of male and female M. parasaissetiae was examined using scanning electron microscopy. The geniculate antennae of male and female M. parasaissetiae were composed of a scape with a basal radicula, a barrel-shaped pedicel, and a long flagellum. Twelve morphologically distinct types of sensilla were identified, including multiporous placoid sensilla, campaniform sensilla, finger-like sensilla, multiporous basiconic sensilla (BS-1), three aporous types of basiconic sensilla (BS-2, BS-3, and BS-4), two types of aporous trichoid sensilla (TS-1 and TS-3), a type of multiporous trichoid sensilla (TS-2), and two types of sensilla chaetica (CH-1 and CH-2). Sex dimorphism in the sensilla composition of M. parasaissetiae is also observed. Major differences between the sexes were found in the number, distribution, shape, structure, and size of the identified sensilla. We also discuss on the functional aspects of these sensilla to elucidate the mechanisms involved in host searching and courtship behavior of M. parasaissetiae.     

Antennal sensilla of male and female Telenomus reynoldsi gordh and coker (Hymenoptera : Scelionidae)

Sensilla on the antennae of both sexes of Telenomus reynoldsi (Hymenoptera : Scelionidae) were studied with the scanning electron microscope to determine their structure and possible function in mating and host recognition. Two types of setiform sensilla occur: curved, grooved sensilla trichodea and erect, stout sensilla chaetica. Horn-like sensilla trichodea curvata are abundant on the male antennae, but are less abundant and only present dorsally on the female. Sensilla basiconica are unique to the ventral surface of the apical 4 segments of the female antennae. Sensilla styloconica are located on A4 and A10 of the female and A7 and A9 of the male. Multiporous grooved sensilla are present on A4, A6, and A11 of the female and A4 and A6-A11 of the male. A possible sex gland is located on the venter of A5 of the male. The functions of sensilla trichodea curvata and sensilla basiconica in courtship and host recognition, respectively, are hypothesized by correlation with behavioral observations.     

Scanning Electron Microscopy Study of the Antennal Sensilla of <Emphasis Type="Italic">Monema flavescens</Emphasis> Walker (Lepidoptera: Limacodidae)

Monema flavescens Walker (Lepidoptera: Limacodidae) is a serious polyphagous defoliator. Using scanning electron microscopy, the external morphology of the antennal sensilla of this pest was examined for a better understanding of the mechanisms of insect-insect and insect-plant chemical communications. The antennae of M. flavescens were filiform in shape, and 11 morphological types of sensilla were found in both sexes. Six types of likely chemosensory sensilla were identified: uniporous sensilla chaetica, multiporous sensilla trichodea, and four types of multiporous sensilla basiconica. The sensilla identified as likely mechanoreceptors included two subtypes of aporous sensilla chaetica, aporous sensilla coeloconica, aporous sensilla styloconica, and Böhm’s bristles, whereas the position of the antennae was monitored by Böhm’s bristles.