Types Of Sensilla Trichodea Research Articles

Fine Structure and Distribution of Antennal Sensilla of the Predatory Clerid Beetle, Thanasimus lewisi (Coleoptera: Cleridae)

The predatory clerid beetle Thanasimus lewisi (Jacobson) (Coleoptera: Cleridae) is an important predator of bark beetles (Scolytidae) and has been used in China for the biological control of the larch bark beetle Ips subelongatus Motschulsky and the spruce bark beetle Ips typographus Linnaeus. In this study, the number, external morphology and distribution of antennal sensilla of T. lewisi were determined using scanning electron microscopy. The filiform antennae of both sexes of both species consist of the scape, pedicel, and nine flagellomeres. Two types of sensilla chaetica (SC1 and SC2), four types of sensilla basiconica (SB1, SB2, SB3 and SB4), two types of sensilla trichodea (ST1 and ST2), and Böhm's bristles (BB) were identified according to the morphology and fine structure of each type of sensilla in both sexes. No difference in shape, structure, sensilla distribution and typology was observed between the sexes. The density of sensilla was greater on the last 3 than on the first 8 segments. SC1, SC2, ST1 and ST2 occurred on all antennal segments in both sexes. SB1, SB2 and SB3 were absent on the first 4 segments of the antennae in both sexes. SB4 were found only on the last 2 segments of the antennae. BB only occurred on the scape and pedicel. The distal antennal sensilla of T. lewisi had notably more sensilla than proximal ones in type and number, indicating this is the main area to detect environmental stimuli for feeding or oviposition. These structures likely have roles in the host locating and habitat searching behavior of adult T. lewisi and suggest future studies on the olfaction and host location behavior of T. lewisi and other coleopteran predators.

Morphological characteristic of malaria vector Anopheles aconitus (Family: Culicidae) revealed by advanced light and scanning electron microscope

Abstract. Supriyomo, Soviana S, Novianto D, Musyaffa MF, Tan S, Hadi UK. 2022. Morphological characteristic of malaria vector Anopheles aconitus (Family: Culicidae) revealed by advanced light and scanning electron microscope. Biodiversitas 23: 3546-3552. Anopheles aconitus (An. aconitus) is one of the primary vectors for malaria in several areas in Indonesia, especially in Java Island. Scanning electron microscope (SEM) is a powerful tool that can differentiate Anopheles spp. Morphology that is difficult to identify by using a light microscope only. The adult of An. aconitus used in this study have been reared in the laboratory. This research is conducted to better understand the Anopheles aconitus' external morphology, such as the head, proboscis, wings, thorax and legs, using advanced light and SEM. Results from an advanced light microscope showed that An. aconitus has palpus with the same length as proboscis with one narrow basal end and two broad distal ends; meanwhile, the apical half of proboscis is pale. Anopheles aconitus has wings with four pale spots on the costa side. Legs are uniformly dark with only very narrow, rather faint pale bands at the joining of segments. Using SEM, we found several types of sensilla trichodea: short-sharp tipped, short-blunt tipped, and long-shaped tipped in antenna, apical proboscis, maxillary palps, abdomen, and legs. Antenna is also covered with microtrichia and sensilla. This research is important for basic necessity in fully understanding and determining of mosquito bionomic due to the development of effective and efficient mosquito vector control strategies.

The variability of antennal sensilla in Naucoridae (Heteroptera: Nepomorpha)

The morphology and distribution of sensilla on the surface of the antennae of the naucorids’ species were studied via scanning electron microscopy. Eleven types of sensilla were identified regarding specific sensory modalities, based on their cuticular morphology. Cuticle morphology identifies five types of sensilla trichodea, four types of sensilla basiconica, one type of sensillum coeloconicum and sensillum ampullaceum. Three new types of mechanosensitive sensilla were found. Moreover, the morphological diversity between the antennae allowed the distinction of ten different antennal types that correspond to different sensillar sets. The sensilla found in Naucoridae share similarities with the sensilla of other nepomorphan taxa, as well as of terrestrial insects. However, no sensillar synapomorphy was found between Naucoridae and Aphelocheiridae.

Morphology and Distribution of Antennal Sensilla of the Predatory Clerid Beetle, Thanasimus substriatus (Coleoptera: Cleridae)

Abstract Thanasimus substriatus (Gebler) (Coleoptera: Cleridae) is an important predator of bark beetles (Scolytidae) and has been used in China for the biological control of the larch bark beetle, Ips subelongatus Motschulsky, and the spruce bark beetle, Ips typographus L. In this study, the number, external morphology, and distribution of antennal sensilla of T. substriatus were determined using scanning electron microscopy. The capitate antennae of both sexes consist of the scape, pedicel, and 9 flagellomeres. Two types of sensilla chaetica (SC1 and SC2), 2 types of sensilla trichodea (ST1 and ST2), 3 types of sensilla basiconica (SB1, SB2, SB3), and Böhm's bristles (BB) were identified according to the morphology and fine structure of each type of sensilla in both sexes. No differences in shape, structure, sensilla distribution, and typology were observed between the sexes. The density of sensilla was greater on the last 3 than on the first 8 segments. SC1 and SC2 occurred on all antennal segments in both sexes. SB1 were located only on the last 5 segments of the antennae. SB2 and SB3 were found only on the last 3 segments of the antennae and were absent on the first 8 segments in both sexes. ST1 and ST2 were absent from the scape and pedicel. BB only occurred on the scape and pedicel. The distal antennal sensilla of T. substriatus had notably more sensilla than proximal ones in type and number, indicating this is the main area to detect environmental stimuli for feeding or oviposition.

Sensilla on antennae and mouthparts of adult spruce bark beetle Ips typographus (Coleoptera: Curculionidae).

The spruce bark beetle, Ips typographus, is an invasive forest pest that occurs across Eurasia. To further understand the mechanism of insect-host chemical communication and the feeding choices of adult I. typographus, we examined the sensilla on the antennae and mouthparts of I. typographus using scanning electron microscopy. No sexual dimorphism in sensilla type or distribution was observed. Ten subtypes of antennal sensilla were identified: sensilla trichodea Types I-III (TR1 , TR2 , and TR3 ); sensilla chaetica Types I and II (CH1 and CH2 ); sensilla basiconica Types I-III (BA1 , BA2 , and BA3 ); sensilla coeloconica (CO); and Böhm sensilla (BS). BA2 were the most abundant among the antennal sensilla in both sexes. Thirteen mouthpart sensilla subtypes were observed: sensilla trichodea Types I-IV (TR1 , TR2 , TR3 , and TR4 ); sensilla chaetica Types I-III (CH1 , CH2 , and CH3 ); sensilla digitiformia (DI); sensilla basiconica Types I-II (BA1 and BA2 ); and sensilla styloconica Types I-III (ST1 , ST2 , and ST3 ). Among these, TR4 were the most abundant in both sexes. The apex of each maxillary and labial palp carried the same sensilla (BA2 , ST1 , ST2 , and ST3 ), although the apex of the maxillary palp contained more total sensilla. The functional roles of each sensilla type are discussed based on their external structure and distribution. The results provide a theoretical basis for further studies on the olfactory and feeding behaviors and electrophysiology of adult I. typographus.

Sensation of the tiniest kind: the antennal sensilla of the smallest free-living insect Scydosella musawasensis (Coleoptera: Ptiliidae).

Miniaturization is a major evolutionary trend prominent in insects, which has resulted in the existence of insects comparable in size to some unicellular protists. The adaptation of the complex antennal multisensory systems to extreme miniaturization is a fascinating problem, which remains almost unexplored. We studied the antennal sensilla of Scydosella musawasensis Hall, 1999 (Coleoptera: Ptiliidae), the smallest free-living insect, using scanning electron microscopy. The antenna of S. musawasensis bears 131 sensilla; no intraspecific variation in the number or position of the sensilla has been revealed. Nine different morphological types of sensilla are described according to their external morphological features and distribution: four types of sensilla trichodea, one type of sensilla chaetica, two types of sensilla styloconica, and two types of sensilla basiconica. Morphometric analysis of the sensilla of S. musawasensis, based on measurements of the lengths and diameters of sensilla and their location and number, showed the absence of significant differences between females and males. Comparative allometric analysis of S. musawasensis and larger Coleoptera showed that the number of sensilla and the size of sensilla chaetica decrease with decreasing body size. However, the number of the types of sensilla and the length and diameter of the multiporous sensilla basiconica revealed no correlation with the body size. Comparison of the acquired data with the results of our earlier study of the antennal sensilla of some of the smallest parasitic wasps is used to put forward hypotheses on the common principles of miniaturization of the antennal sensory systems of insects.

Comparative analysis of antennal fine structure of Goniagnathus punctifer, Stirellus yeongnamensis and Stirellus indrus (Hemiptera: Cicadellidae: Deltocephalinae)

The morphology of the antennae of adult specimens of Goniagnathus punctifer (Walker, 1858), Stirellus yeongnamensis (Kwon and Lee, 1979) and Stirellus indrus (Distant, 1908) was studied using SEM (scanning electron microscope). The antennae of these three leafhopper species are similar overall to antennae of other leafhoppers, consisting of three segments: a short scape, a cylindrical pedicel and an elongate, hair-like flagellum. Five kinds of sensilla are found on G. punctifer, including two types of sensilla trichodea (St I and St II), two types of sensilla basiconica (Sb I and Sb II), one type of sensilla chaetica (Sch I), two types of sensilla coeloconica (Sco I and Sco II), and one type of sensilla campaniformia (Sca I). Sensilla on the 1st and 2nd flagellomere of male G. punctifer tentatively identified as Sb II have a unique shape not yet observed in other leafhoppers. Five kinds of sensilla are found on S. yeongnamensis, including two types of sensilla trichodea (St I and St II), one type of sensilla basiconica (Sb I), two types of sensilla chaetica (Sch I and Sch II), one type of sensilla coeloconica (Sco I), and two types of sensilla campaniformia (Sca I and Sca II). Five kinds of sensilla are found on S. indrus, including two types of sensilla trichodea (St I and St II), one type of sensilla basiconica (Sb I), two types of sensilla chaetica (Sch I and Sch II), two types of sensilla coeloconica (Sco I and Sco II) and one type of sensilla campaniformia (Sca II). The antennal surfaces of these three leafhopper species also have large numbers of brochosomes and squamiform denticles. No significant differences in antennal morphology were observed between males and females of Stirellus Osborn and Ball, 1902. A table summarizing types and locations of antennal sensilla in previously studied leafhoppers is provided.

How Does the Intricate Mouthpart Apparatus Coordinate for Feeding in the Hemimetabolous Insect Pest Erthesina fullo?

Simple SummaryTo better understand the feeding mechanism of Erthesina fullo, the fine structure of the mouthparts is examined with scanning electron microscopy, and feeding performance are observed directly under laboratory conditions for the first time. The adult feeding process involves several steps, including exploring and puncturing of the host plant epidermis, a probing phase, an engorgement phase, and removal of the mouthparts from the host tissue. Proceeding from labium towards the mandibular stylets, the movement pattern becomes increasingly stereotypical, including the sensilla on the tip of the labium probing, the labium making an elbow-like bend between the first and second segment, the base of the stylet fascicle housing in the groove of the labrum, the mandibular stylets penetrating the site and maxillary stylets feeding. The morphology of mouthparts is similar to those of other Heteroptera. The four-segmented labium has eleven types of sensilla. The mandibular stylet tips have two nodules preapically on the convex external surface. The structure and function of the mouthparts are adapted for the phytophagous feeding habit in this species. This study increases the available detailed morphological and behavioral data for Hemiptera and will potentially contribute to improving our understanding of this pest’s feeding behavior and sensory mechanisms.The yellow marmorated stink bug, Erthesina fullo (Thunberg, 1783), is a major pest of certain tree fruits in Northeast Asia. To better understand the feeding mechanism of E. fullo, the fine structure of the mouthparts, including the distribution and abundance of sensilla, are examined with scanning electron microscopy (SEM), and their functions are observed directly under laboratory conditions. The feeding performance is described in detail and illustrated for the first time. The adult feeding process involves several steps, including exploring and puncturing of the host plant epidermis, a probing phase, an engorgement phase, and removal of the mouthparts from the host tissue. Proceeding from labium towards the mandibular stylets, the movement pattern becomes increasingly stereotypical, including the sensilla on the tip of the labium probing, the labium making an elbow-like bend between the first and second segment, the base of the stylet fascicle housing in the groove of the labrum, the mandibular stylets penetrating the site and maxillary stylets feeding. In terms of morphology, the mouthparts are similar to those of other Heteroptera, consisting of a triangular pyramidal labrum, a tube-like and segmented labium with a deep groove on the anterior side, and a stylet fascicle consisting of two mandibular and two maxillary stylets. The four-segmented labium has five types of sensilla basiconica, three types of sensilla trichodea, two types of sensilla campaniformia and 1 type of sensilla coeloconica. Among them, sensilla trichodea one and sensilla basiconica one are most abundant. The tripartite apex of the labium is covered with abundant sensilla trichodea three and a few sensilla basiconica 5. The mandibular stylet tips have two nodules preapically on the dorsal margin of the convex external surface, which may help in penetrating plant tissue and anchoring the mouthparts. The externally smooth maxillary stylets interlock to form a larger food canal and a smaller salivary canal. The structure and function of the mouthparts are adapted for the phytophagous feeding habit in this species. Similarities and differences between the mouthparts of E. fullo and those of other Heteroptera are discussed.

Structure and sensilla of the mouthparts of Alobaldia tobae, Maiestas dorsalis and Stirellus indrus (Hemiptera: Cicadellidae: Deltocephalinae)

The morphology of adult mouthparts of the leafhoppers Alobaldia tobae, Maiestas dorsalis and Stirellus indrus was studied using a scanning electron microscope. The mouthparts are of the typical piercing–sucking type, similar to mouthparts found in other hemipteran insects, and comprise a three-segmented labium with a deep groove in the anterior side, a stylet fascicle consisting of two mandibular and two maxillary stylets, and a small cone-shaped labrum. The mandibular stylets, located laterad of the maxillary stylets, have sculpturing on their tips. The maxillary stylets are interlocked to form a larger food canal and a smaller salivary canal. Sensilla detected on the three leafhopper species were at different locations on the labium. Three kinds of sensilla were found on the Alobaldia tobae and Maiestas dorsalis labium, including two types of sensilla trichodea (I and II), two types of sensilla basiconica (I and II), and one type of sensilla coeloconica (Sco I). Three kinds of sensilla were found on the Stirellus indrus labium, including three types of sensilla trichodea (I, II and III), two types of sensilla basiconica (I and II), and one type of sensilla coeloconica (Sco I). Among them, sensilla trichodea I are the most abundant on all of three species. This is the first report of sensilla coeloconica (Sco I) and sensilla trichodea III on the mouthparts of Deltocephalinae. Sensilla trichodea I (St I) were also found on the surface of the Stirellus indrus labrum, which is also a first report in the Deltocephalinae. These sensilla may be involved in host recognition and are likely chemo- or mechanosensory, or both. The potential functions of the sensilla are discussed. The morphology of mouthparts and the distribution of sensilla on the labium in Alobaldia tobae, Maiestas dorsalis and Stirellus indrus are discussed with respect to their possible functional significance.

Sensory armature and stylets of the mouthparts of Stephanitis nashi (Hemiptera: Cimicomorpha: Tingidae), their morphology and function

Mouthparts are important appendages that are specialized for detection of food sources and feeding. The pear lace bug, Stephanitis nashi Esaki and Takeya, is a major pest of pear in China, sucking the sap and affecting plant growth. Fine structure of the mouthparts including distribution and abundance of receptor sensilla occurring of adult S. nashi was examined using scanning electron microscopy and structural details are described for the first time. The mouthparts of S. nashi are generally similar to those of other Hemiptera and consist of a pyramidal labrum, a tube-like segmented labium, and a stylet fascicle made up of two mandibular and two maxillary stylets. The four segments of the labium differ in length and have five classes of sensilla including 3 types of sensilla basiconica (I, II, III), 2 types of sensilla trichodea (I, II), 1 type of sensillum campaniformium, 1 type of flower-like sensillum and a sensillum placodeum. Sensilla trichodea II are distributed on each segment of the labium. Sensilla basiconica I occur on the base of the second and fourth segment. The labial tripartite apex composes of two sensory fields and a rostral lid. Each sensory field possesses 2 sensilla basiconica II, 9 sensilla basiconica III, 1 flower-like sensillum and 1 sensillum placodeum. The mandibular stylet tips have about 30 pairs of lateral minor teeth, which may help in penetrating leaves. Externally, the end of each maxillary stylet is smooth; internally it has five teeth. There is no obvious difference between males and females in the distribution, number and types of sensilla. The mouthparts morphology of S. nashi, is consistent in many respects to that of many other phytophagous hemipterans but appear to include some features unique to the Tingidae and others that closely resemble those of both phytophagous and predaceous Miridae.

Sensory Receptors Associated with the Labial Tip and Precibarium of Philaenus spumarius L. (Hemiptera: Aphrophoride).

The meadow spittlebug, Philaenus spumarius (Linnaeus) (Hemiptera: Aphrophoridae), is an important vector for the xylem-limited bacterium Xylella fastidiosa (Wells, Raju, Hung, Weisburg, Mandelco-Paul, and Brenner), which is associated with olive quick decline syndrome in southern Italy. The mouthparts of Hemiptera have important roles in host plant selection, feeding behavior and for vectoring pathogens that cause plant diseases. In this study, the functional morphology of the sensory structures located on the labium tip and precibarium of P. spumarius was investigated using scanning and transmission electron microscopy. The labium tip is composed of two symmetrical sensory complexes, each with five different types of sensilla: aporous sensilla trichodea type 1 and 2; uniporous sensilla chaetica type 1 and 2; and multiporous sensilla basiconica. The precibarium of P. spumarius has two kinds of sensory structures: bulbous sensilla and papillae sensilla. In particular, two groups of sensilla are located on the epipharynx: a distal group that consists of ten papillae sensilla and a proximal group composed of six papillae sensilla and two bulbous sensilla, while the hypopharynx has only two papillae sensilla. The involvement of these sensory structures in the context of feeding behavior and pathogen transmission is discussed.

Fine structure and distribution of antennal sensilla of stink bug <i>Arma chinensis</i> (Heteroptera: Pentatomidae)

Scanning electron microscopy was used to examine the morphology, ultrastructure, and distribution of antennal sensilla of the stink bug Arma chinensis. Two types of sensilla trichodea (ST1–2), four types of sensilla basiconica (SB 1– 4), one type of sensilla chaetica (SCH), one type of sensilla cavity (SCA) and one type of sensilla coeloconica (SCO) were distinguished on the antennae in both sexes. ST1 and ST2 were absent from the scape and pedicel. SB1 were absent from the scape. SB2 were distributed throughout the antennae. SB3 were located on the second pedicel and the two flagellomeres. SB4 were absent from the second flagellomere. SCH was observed on the second pedicel and the two flagellomeres. SCA and SCO occurred only on the second flagellomere. SB1 clusters occurred on the distal part of the second flagellomere. We compared the morphology and structure of these sensilla to other Heteroptera and discuss their possible functions.

Morphology and Distribution of the Antennal Sensilla of Two Species, Megalurothrips usitatus and Thrips palmi (Thysanoptera: Thripidae).

The morphology and distribution of the antennal sensilla of Megalurothrips usitatus Bagnall and Thrips palmi Karny were examined using scanning electron microscopy (SEM). These are serious pests of various economically important crops, and their antennae are important in chemical communication. The antennae of both species consist of a scape, pedicel, and flagellum, but the flagellum of M. usitatus is made up of six sub-segments, whereas that of T. palmi consists of five sub-segments. Seven morphological sensilla types, including Böhm bristle (BB), sensilla campaniformia (Sca), three types of sensilla basiconica (Sb1, Sb2 and Sb3), two types of sensilla chaetica (Sch1 and Sch2), sensilla styloconica (Sst), sensilla trichodea (St), and sensilla cavity (Scav), were recorded in both species. The scape and pedicels exhibited Sch1, BB and Sca. The flagellum exhibited two types of Sch, three types of Sb, St, Sst and Scav. Based on these results, the putative function of the sensilla of M. usitatus and T. palmi are also discussed.

Fine Morphology of the Mouthparts in Cheilocapsus nigrescens (Hemiptera: Heteroptera: Miridae) Reflects Adaptation for Phytophagous Habits.

To obtain a better understanding of feeding adaptations, the fine structure of the mouthparts in adults of Cheilocapsus nigrescens Liu and Wang, including the sculpture and interlocking mechanisms of the stylets and distribution and abundance of sensilla located on the labium, were studied using scanning electron microscopy. The mouthparts are similar to those of previously studied mirid species in most aspects and composed of a cone-shaped labrum, a tube-like, four-segmented labium with a deep groove on the anterior side, and a stylet fascicle consisting of two mandibular and two maxillary stylets. Each mandibular stylet tip has about 6–8 indistinctive notches, which help in penetrating the leaf surface. A series of transverse squamous textures are present on the adaxial surface of the mandibular stylets. The maxillary stylets interlock to form a food canal and a salivary canal, equipped with an external longitudinal process that engages grooves in the mandibular stylets. Three kinds of sensilla, including four types of sensilla basiconica (I, II, III, and IV), four types of sensilla trichodea (I, II, III, and IV), and one type of sensillum campaniformium, occur at different locations on the labium. Among them, sensilla trichodea I and II are the most abundant; sensilla basiconica II occurs between the first segment and second segment, and between the third and fourth segment. The tripartite apex of the labium consists of two lateral lobes and an apical plate. Each lateral lobe possesses a field of 11 sensilla basiconica IV and 1 sensillum trichodeum IV. The morphology of the mouthparts and the distribution of sensilla located on the labium in C. nigrescens are discussed with respect to their possible taxonomic and functional significance. In particular, the indistinct notches of the mandibular stylet and smooth inner surface of the right maxillary stylets are suited primarily for phytophagy.

The sensilla trichodea-biased EoblPBP1 binds sex pheromones and green leaf volatiles in Ectropis obliqua Prout, a geometrid moth pest that uses Type-II sex pheromones

Pheromone-binding proteins (PBPs) are considered to play critical roles in sex pheromone detection. Lepidopteran moths can be divided into two taxa, those that use Type-I sex pheromones, such as C10–C18 unsaturated aldehydes, alcohols and acetates, and those that use Type-II pheromones, which are C17–C23 polyunsaturated hydrocarbons and their epoxide derivatives. To date, nearly all the characterized PBPs have been reported in moths with Type-I sex pheromones, and the physiological functions of PBPs in moths that use Type-II sex pheromones remains unclear. In the present study we functionally examine EoblPBP1 in Ectropis obliqua Prout, an important geometrid moth pest that uses Type-II sex pheromones. The phylogenetic analysis of the sequence indicated that EoblPBP1 clustered together with ScerPBP1, a geometrid PBP for detecting Type-II sex pheromones. Scanning electron microscopy showed that E. obliqua moths of both sexes mainly had six types of antennal sensilla, including two types of sensilla trichodea, Str-I and Str-II, sensilla basiconica (Sba), sensilla styloconica (Sst), sensilla chaetica (Sch) and sensilla auricillica (Sau). Of these, Str-I was confirmed to be male moth-specific and had five different subtypes. Fluorescence in situ hybridization revealed that EoblPBP1 was primarily expressed at the base of Str-I. A comparative binding assay showed that recombinant EoblPBP1 bound three sex pheromone components of E. obliqua, demonstrating its involvement in the detection of Type-II sex pheromones. Besides, EoblPBP1 also highly bound unsaturated acetates pheromones and the green leaf volatiles. These results indicate that PBP1 is associated with detecting Type-II sex pheromones in E. obliqua but cannot differentiate Type-II sex pheromones from Type-I sex pheromones or green leaf volatiles. Our findings provide a foundation for further study on molecular basis of Type-II sex pheromone recognition in lepidopteran moths.

Surface Ultrastructure of Antenna and Distribution of Sensilla in the Leptogenys chinensis (Mayr) (Fabricus) (Formicidae: Hymenoptera)

Ants have well developed pair of antenna with sensory system used in chemical communication for social lives. The antennae comprise of two parts scape and funiculus. Funinculus contain single segmented pedicel and ten segmented flagellum. The surface micro-morphology of the antennal sensilla of Leptogenys chinensis worker shows presence of various types of sensilla viz. sensilla trichodea, sensilla trichodea curvata, sensilla basiconica, sensilla coeloconica, sensilla chaetica, sensilla coelocapitular. Sensilla trichodea is distributed on all parts of antenna. Sensilla trichodea curvata type III is typically present on flagellar segments only. Sensilla basiconica with arrowhead present on scape ball is slightly different than the sensilla basiconica with rounded head present on flagellar tip. Sensilla coelocapitular is observed only on the flagellar tip. On the joint of scape ball and pedicilar shaft three types of sensilla trichodea are present on the ball ridge while, sensilla basiconica distributed on dorso-lateral margin of ball. KEYWORDS: Ant, Leptogenys, antenna, sensilla, SEM

Sexual dimorphism in antennal sensilla of Parthenium beetle <i>Zygogramma</i> <i>bicolorata</i>

In the present study, scanning electron microscopy was used to investigate the ultrastructure of sensilla present on the antennae of male and female Zygogramma bicolorata. The antennae in this insect consist of the scape, pedicel, and nine flagellomeres. Six types of sensilla were identified: sensilla trichodea type 1 and 2 (ST1, ST2), sensilla cavitae (SCa), sensilla chaetica (SCh), and sensilla basiconica type 1 and 2 (SB1, SB2). Sensilla were characterized on the basis of their size and density to find out whether sexual dimorphism exists in this species or not. We observed that the size of the antennomeres was comparatively larger in males than females. Moreover, sensilla chaetica were found on all antennomers and have the qualification of being the longest type, suggesting that they probably have a role in mechanoreception. There was an abundance of sensilla trichodea in both males and females, indicating its function as a chemoreceptor. Sensilla basiconica are believed to sense sex pheromones and hence their abundance was more in males as compared to females.

Antennal Morphology and Localization of a Pheromone-Binding Protein of Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae).

In the sensory system of insects, olfactory sensilla constitute important functional elements for discriminating odors. Therefore, we used light microscopy and scanning electron microscopy to investigate the morphology and distribution of sensilla in the antennae of Lobesia botrana (Denis & Schiffermüller). In addition, we studied the expression of the gene encoding for pheromone-binding protein 1 (LbotPBP1) by in situ hybridization. Lobesia botrana antennae are filiform and are subdivided into three segments: scape, pedicel, and flagellum. The number of flagellum and their overall length were significantly higher and longer in males than in females. Six morphological types of sensilla (trichodea, chaetica, coeloconica, auricillica, basiconica, and styloconica) were identified on the antennae of both sexes. Trichodea sensilla were the most abundant on the antennae of L. botrana, and three subtypes, discerned by their lengths, were observed. However, sensilla trichodea subtype III was only present in male antennae. Moreover, LbotPBP1 expression was restricted to this type of sensilla, thus confirming its olfactory role, specifically under the context of sexual pheromone perception.

Sensilla on six olfactory organs of male Eogystia hippophaecolus (Lepidoptera: Cossidae).

Eogystia hippophaecolus (Hua et al.) is an important boring pest that primarily damages sea buckthorn, causing large ecological and economic damages in China. In this study, we used scanning electron microscopy to investigate the sensilla on six olfactory tissues of male E. hippophaecolus: antennae, labial palps, external genitals, propodeum, mesopodium, and metapedes. On the antennae, two types of sensillum trichodea, two types of sensillum basiconica, a type of sensillum coeloconica, and Böhm's bristles were found. The labial palps had sensilla trichodea and chaetica. On the external genitals, three types of sensilla trichodea were the only sensilla. Böhm bristles were found on the base of the tibia and at the terminus of the tarsus. Most sensilla were distributed on the tarsus of the three pairs of legs, and notably, a majority of which were sensilla trichodea and sensilla chaetica, were on the pretarsus and telotarsus of the three pairs of legs. In this study, the distribution, number, type, and morphology of the sensilla on six olfactory organs of E. hippophaecolus were determined, which established the foundation for a future immunohistochemical search of olfactory proteins. RESEARCH HIGHLIGHTS: Eogystia hippophaecolus is a serious pest of seabuckthorn. The distribution, number, type, and morphology of olfactory sensilla of E. hippophaecolus are determined. The function and distribution of sensilla are compared with those of other insects.

Species- and sex-specific distribution of antennal olfactory sensilla in two tortricid moths, Epiphyas postvittana and Planotortrix octo

We investigated the morphology and distribution of antennal sensilla in males and females of two tortricid moths, Epiphyas postvittana and Planotortrix octo, by scanning electron microscopy. The number and overall length of flagellomeres were significantly greater in females than in males in both species. The antennae of each species bearing six morphological types of sensilla (trichodea, basiconica, coeloconica, auricillica, chaetica, and styloconica), with different numbers and distributions along the antennae. Among these sensilla, four types (trichodea, basiconica, coeloconica, and auricillica) displayed multi-porous cuticular surfaces, indicating that their primary sensory function is olfactory. Each of these four types of sensilla could be further classified into subtypes according to their size, shape, and surface structure. Both E. postvittana and P. octo exhibited sexual dimorphism of the profiles of antennal olfactory sensilla. Trichoid sensilla were the most abundant type in both species. Subtype I trichoid sensilla were male-specific in both species, indicating that they are responsible for the perception of conspecific female sex pheromone. By contrast, subtype II trichoid sensilla were more abundant in female antennae in both species, suggesting that some subtype II trichoid sensilla are involved in female-specific behaviors, such as oviposition. Chaetic and styloconic sensilla displayed relatively even distributions along the antennae. Our results indicate that the antennae of E. postvittana and P. octo have species-specific and sex-specific profiles of olfactory sensilla. The morphological information obtained in our study provides a basis for electrophysiological and behavioral studies of the olfactory sensory function of each morphological type of sensilla.