Sensilla Chaetica Research Articles

Morphological and Ultrastructural Characterization of Antennal Sensilla and the Detection of Floral Scent Volatiles in Eupeodes corollae (Diptera: Syrphidae).

The olfactory sensing system of the syrphid fly Eupeodes corollae is essential in pollination and prey localization, but little is known about the ultrastructural organization of their olfactory organs. In this study, the morphology, distribution, and ultrastructural organization of antennal sensilla of E. corollae in both sexes were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Neuronal responses of a subtype of sensilla basiconica to floral scent compounds were recorded by single sensillum recording (SSR). Ten morphological types, including Böhm bristles, sensilla chaetica, microtrichiae, sensilla trichodea, sensilla basiconica, sensilla clavate, sensilla coeloconica, sensilla styloconica, sensilla placodea, and sensory pit, were identified. Except for Böhm bristles and sensilla chaetica, which were distributed on the scape and pedicel of E. corollae antennae, innervated sensilla were densely distributed on the flagellum, a vital sensory organ. Further, observing ultrastructural organization showed that the sensilla trichodea, basiconica, and clavate are single-walled with multiple nanoscale pores perforating the cuticle. Sensilla coeloconica are double-walled and have no wall pores, but instead, have longitudinal grooves along with the pegs. Sensilla chaetica, Böhm bristles, and microtrichiae did not have wall pores on the cuticle or sensory cells at the base. The SSR results indicated that neuron B housed in the subtype of sensilla basiconica I (SBI) mainly responded to methyl eugenol and other aromatic compounds. Overall, our results provide valuable information to understand the morphology and ultrastructure of antennal sensilla from E. corollae. These findings are beneficial for the studies of the neuronal function map of olfactory sensilla and for determining evolutionary relationships in Diptera.

Morphology of the Antennal Sensilla of Notonectoidea and Comparison of Evolutionary Changes in Sensilla Types and Distribution in Infraorder Nepomorpha (Insecta: Heteroptera).

Simple SummaryAntennal sensilla are important sensory organs for insects. According to their morphological structures, they respond to different chemical or mechanical stimuli. The antennae of the studied families of water insects (Notonectidae, Pleidae and Helotrephidae) are short and concealed under the head, leaving a small amount of space for the existence of sensory structures. Nevertheless, six main types of sensilla have been discovered on the surfaces of these antennae. The morphological types described in this study were further compared with other studies on the antennal sensilla of water bugs (Nepomorpha) in order to compare their evolutionary changes within the group.This article introduces the results of a study of three families of Nepomorpha and is the last part of a series of studies that sums up our work on the morphologies of the antennal sensory structures in this taxon. The morphologies and distribution of the sensilla in the families Notonectidae, Pleidae and Helotrephidae were studied under a scanning electron microscope. Six main types (sensilla trichodea, chaetica, campaniformia, basiconica, ampullacea and coeloconica) and ten subtypes (five subtypes of sensilla trichodea and five subtypes of sensilla basiconica) were described. The results were compared with other studies on the antennal sensilla of Nepomorpha in order to assess evolutionary changes within the infraorder. With the use of cladistics analysis, the monophyly of the families Nepidae, Micronectidae, Corixidae and Gelastocoridae was supported. On the other hand, the occurrence of some clades forming superfamilies was weakly supported by bootstrap analysis. These results, supported by presence of the numerous autapomorphies, suggest that antennal sensilla evolved within inner groups.

Ultrastructure of the Sensilla on the Antennae and Mouthparts of Bean Weevils, Megabruchidius dorsalis (Coleoptera: Bruchinae).

Simple SummaryIn this paper, we used scanning electron microscopy (SEM) to describe the morphological types, number of sensilla, and their distributions on the antennae and mouthparts of both sexes of the bean weevil, Megabruchidius dorsalis (Coleoptera: Bruchinae). The results showed twelve subtypes on antennal sensilla and five types of sensilla on maxillary and labial palps. No sexual dimorphism in sensilla type was observed, but there were variations between male and female in the numbers and distribution along with the antennae. In addition, we discussed potential function related to structure, through comparisons with previous studies of bruchids and other insects. This information will support further studies of semiochemicals as effective biological controls of this pest.Megabruchidius dorsalis (Fåhraeus, 1839) (Coleoptera: Bruchinae) is an important pest that damages the seeds of Gleditsia L. (Fabaceae: Caesalpinioideae). This beetle searches for host plants with its sensory system. To further explore the mechanisms of host location and to understand the ultrastructure of M. dorsalis, we examined the morphology and distribution of its sensilla on the antennae and mouthparts of male and female adults, using scanning electron microscopy (SEM). Both male and female antennae are serrated and can be divided into scape, pedicel, and flagellum. There were seven types and eight subtypes of antennal sensilla, including Bőhm bristles (BB), two subtypes of sensilla trichoid (ST1, ST2), two subtypes of sensilla chaetica (SC1, SC2), four subtypes of sensilla basiconic (SB1, SB2, SB3, SB4), sensilla cavity (SCa), sensilla auricillica (SA), and sensilla gemmiformium (SG). Five types of maxillary and labial palp sensilla in the mouthparts were observed: sensilla chaetica (SC), sensilla trichoidea (ST), sensilla styloconica (SSt), sensilla coeloconica (SCo), and sensilla digitiform (SD). No sexual dimorphism in sensilla type was observed, but there were variations between males and females in the numbers and distribution along the antennae. There were more SA in males than in females, while the number of ST sensilla in the maxillary palps were lower in males than in females. ST1 were most abundant in both sexes. We discussed potential function related to structure via comparisons with previous investigations of bruchids and other insects. Our results provide a theoretical basis for further studies on sensory physiological function, using semiochemicals as effective biological controls of M. dorsalis.

Structure and distribution of antennal sensilla in Pseudosymmachia flavescens (Brenske) (Coleoptera: Scarabaeidae: Melolonthinae).

Morphology, microstructure, and distribution of antennal sensilla were compared between female and male Pseudosymmachia flavescens (Brenske) (Coleoptera: Scarabaeidae: Melolonthinae). Lamellate antennae of P. flavescens were shown to have typical scape, pedicel, and flagellum segments. The flagellum consists of a four-segmented funicle and a three-segmented club. The lengths of their pedicel and funicle were found to be similar in females and males. Distinct sexual differences were observed in the length of lamellar segments. Nine types/subtypes of sensilla were identified on the antennae of both sexes, including Böhm sensilla, sensilla trichodea, sensilla basiconica (SB), and two subtypes for sensilla chaetica, sensilla coeloconica, and sensilla placodea each. Olfactory sensilla (e.g., SB and placodea) are mainly located on three lamellar segments of the antennal club. Variation was also seen in abundance of various types of antennal sensilla, with males possessing significantly more sensilla than females. Sensilla placodea were the most abundant, and their number in males was twice of that in females, showing a clear sexual dimorphism. The difference in the distribution of sensilla placodea might reflect their roles in sexual chemical communication.

Morphology and distribution of antennal sensilla in adults of Xylotrechus quadripes.

Xylotrechus quadripes (Chevrolat) is the serious woodborer pest of arabica coffee (Coffea arabica L.). To further elucidate the behavior mechanism of the insect based on chemical odorant and to advance effective trapping methods, the typology, distribution, and abundance of antennal sensilla were investigated meticulously in both sexes of X. quadripes by scanning electron microscopy. The filiform antennae of both sexes are composed of 11 segments, namely the scape, pedicel, and nine flagellomeres (f1-9). Ten types (14 subtypes) of sensilla were identified morphologically: sensilla chaetica (three subtypes, Ch.1-3), sensilla basiconica (three subtypes, Ba.1-3), Böhm bristles (Bb), sensilla dentiform (De), sensilla trichodea (Tr), sensilla auricillica (Au), sensilla campaniformia (Ca), grooved peg sensilla (Gp), cuticular pores (Cp), and a newly observed sensillum, named sensilla cone (Cone). The sensilla were mainly distributed in flagellomeres, and the types and amounts increased in frequency from scape to the ninth flagellomere. The numbers of sensilla were the highest on the antennal dorsal side, while the lowest on the ventral side. The types of sensilla were the most abundant on the lateral side, and two sensilla basiconica (Ba.1-2) were found exclusively. The average number of Tr, Ba, and Au on the antenna of the males was significantly greater than females, while the Gp and Cp on the antenna of the females were significantly greater than males. Ca was exclusively occurred on the male antennae but was absent in females. This study discusses the putative functions of the antennal sensilla in adults of X. quadripes based on their characteristics in related species' sensilla, and these results provide an important foundation to clarify the ecological adaption, olfactory recognition mechanism, and to develop the chemical ecology control of X. quadripes.

Morphological characterization and distribution of antennal sensilla of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) using scanning electron microscopy.

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a serious polyphagous pest of various field and horticultural crops. A complete knowledge on the morphological features of antennal sensory structures is essential for efficient semiochemical-based control methods. The external structure and distribution of antennal sensilla in male and female adults of H. armigera were investigated using scanning electron microscopy. Eight distinct morphological types of sensilla were identified in both sexes: sensilla trichodea, sensilla basiconica, sensilla auricillica, sensilla coeloconica (multiporous), sensilla chaetica (uniporous), sensilla styloconica, sensilla squamiformia, and Böhm sensilla (aporous) in varying numbers and distribution along the length of the antennae. Of these sensilla, the most widespread are sensilla trichodea and sensilla basiconica on the antennae of both sexes. Female antennae have comparatively greater number of sensilla trichodea than male antennae. Among eight types of sensilla, sensilla basiconica, auricillica, styloconica type II, squamiformia, and Böhm sensilla were identified and reported for the first time in H. armigera. Sexual dimorphism in H. armigera was mainly detected as the variations in sensilla shape, numbers, and distribution of each type of sensilla. The sexual difference was observed in the numbers of sensilla coeloconica, chaetica, styloconica, and squamiformia per flagellomere. The possible functions of these sensilla were discussed in view of previously reported lepidopteran insects. The findings provide fundamental information on the morphology and distribution of antennal sensory structures in H. armigera. It would be useful for further detailed studies on physiological and behavioral function of each sensillum type and helpful for formulating related pest control methods.

Scanning electron microscopy of sensilla on the labial and maxillary palps of adult Callidiellum villosulum Fairmaire (Coleoptera: Cerambycidae).

This study used scanning electron microscopy (SEM) to observe the morphology and sensilla of the labial and maxillary palps of adult Callidiellum villosulum Fairmaire between sexes. Combining behavioral activities may provide an effective control target for this pest. In this study, the results showed that there were three segments on the labial palps and four segments on the maxillary palps. The length and width of each segment of the labial and maxillary palps were significantly larger in females than in males. Four types of sensilla were found on the labial and maxillary palps of both sexes of adult C. villosulum: sensilla basiconica (SB I, II, III, and IV), sensilla chaetica (SCh I and II), sensilla placodea (SP), and sensilla campaniformia (SCa). SB IV, SCa, and Sh II were significantly more developed on female labial and maxillary palps than on males', which may be related to their oviposition behavior. By contrast, SB I was more significantly developed on males than on females, which may be related to their mating selection. At the same time, for both sexes, the numbers of Sh I and Sh II on the maxillary palps were significantly higher on labial palps. Maxillary palps could be inferred to potentially play a more important role than the labial palps in the activities of adult C. villosulum. Results will help us further understand the host selection and egg-laying behavior of adult C. villosulum. Such an understanding shall greatly promote the information-based design of pest control methods.

Olfactory Sensilla and Olfactory Genes in the Parasitoid Wasp Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae).

Simple SummaryParasitic wasps are the major natural enemies of many organisms, and therefore they are broadly used in the biological control of numerous agricultural and horticultural pests. For example, Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) is a tiny natural egg parasitoid of various agricultural pest insects, including Plutella xylostella, Helicoverpa armigera, Spodoptera frugiperda and Ectomyelois ceratoniae. However, how T. pretiosum seek and localise host insect eggs is still not clear. The olfactory system is critical in guiding insect behaviours, including mating, feeding and oviposition, which play pivotal roles in the interactions between parasitoid wasps and their hosts. This project aimed to investigate T. pretiosum major olfactory tissue (antennae) and the olfactory genes, including odorant binding proteins (OBPs) and odorant receptors (ORs). T. pretiosum adult antennae were examined under scanning electron microscopy, and four types of olfactory sensilla were observed. Using T. pretiosum genome, 22 OBPs and 105 ORs were identified, which were further compared with olfactory genes of other Hymenoptera insect species. The expression patterns of OBPs between T. pretiosum male and female adults were examined to identify female- or male-specific OBPs. This study enriches our knowledge of T. pretiosum olfactory system and will help better use it in the integrated pest management (IPM) for many insect pest species.Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) is a tiny natural egg parasitoid of several agricultural pest insects, which has been widely used in the biological control for Plutella xylostella, Helicoverpa armigera, Spodoptera frugiperda and Ectomyelois ceratoniae. However, limited studies have been conducted on T. pretiosum olfactory system, which is critical in regulating insect behaviours. In this study, T. pretiosum adult antennae were investigated under ascanning electron microscopy (SEM). Four types of olfactory sensilla were observed, including chaetica sensilla (CS), trichoid sensilla (TS), faleate sensilla (FS) and placoid sensilla (PS). Using T. pretiosum genome, 22 putative odorant binding proteins (OBPs) and 105 odorant receptors (ORs) were identified, which were further compared with olfactory genes of Apis mellifera, Nasonia vitripennis and Diachasma alloeum. The expression patterns of OBPs between T. pretiosum male and female adults were examined by quantitative real time PCR (qRT-PCR) approaches. Three female-specific OBPs (TpreOBP19, TpreOBP15 and TpreOBP3) were identified, which may play crucial roles in T. pretiosum host-seeking and oviposition behaviours. This study enriches our knowledge of T. pretiosum olfactory genes and improves our understanding of its olfactory system.

Ultramorphological Comparison of Proboscis and Associated Sensilla of Scotogramma trifolii and Protoschinia scutosa (Lepidoptera: Noctuidae)

Simple SummaryThe clover cutworm, Scotogramma trifolii Rottemberg, and the spotted clover moth, Protoschinia scutosa (Denis & Schiffermuller), are worldwide polyphagous pests, and the larvae feed mainly on the leaf backs of many agricultural crops. However, the food sources and feeding habits of the adults are still poorly known. We investigated the ultramorphology of the proboscis and associated sensilla of S. trifolii and P. scutosa using scanning electron microscopy. The results show that the proboscises of S. trifolii and P. scutosa are structurally similar, both including three sensillum types and three zones (Zone 1–3). The sensillum chaeticum is non-porous hair-like, the sensillum basiconicum is a short smooth cone with a sensory pore on the blunt tip, and each sensillum styloconicum is composed of a uniporous sensory cone inserted into a ribbed stylus. In addition, the movement and fluid uptake mechanisms of the proboscis and the possible function of sensilla are briefly discussed.The proboscis is an important feeding organ for the glossatan moths, mainly adapted to the flower and non-flower visiting habits. The clover cutworm, Scotogramma trifolii Rottemberg, and the spotted clover moth, Protoschinia scutosa (Denis & Schiffermuller), are serious polyphagous pests, attacking numerous vegetables and crops, resulting in huge economic losses. However, the feeding behavior and mechanisms of the adult stage remain unsatisfactorily explored. In this study, the proboscis morphology of S. trifolii and P. scutosa are described in detail using scanning electron microscopy, with the aim of investigating the morphological differences and feeding behavior of these two species. The proboscises of S. trifolii and P. scutosa are similar in morphology and structure and are divided into three zones (Zone 1–3) based on the morphological changes of the dorsal legulae. Three sensillum types are located on the proboscises of both species, sensilla chaetica, sensilla basiconica, and sensilla styloconica. Significant differences were observed in the length of the proboscis and each zone between these two species, as well as in sensilla size and number. Based on the morphology of the proboscis and associated sensilla, S. trifolii and P. scutosa are potential flower visitors, which was also reinforced by the pollen observed at the proboscis tip. These results will strengthen our understanding of the structure of the proboscis related to the feeding behavior of Noctuidae.

Antennal sensilla in an anophthalmic wood-dwelling species, Clinidium canaliculatum, Costa 1839 (Coleoptera, Rhysodidae).

The habit of feeding on slime moulds (Myxomycetes) commonly present in litter or dead wood requires specific morphological adaptations of the mouthparts and sensory structures involved in the search for habitat and food. In this study, the external morphology of antenna and its sensilla were studied using scanning electron microscopy in the saproxylic beetle, Clinidium canaliculatum, Costa 1839 (Coleoptera, Rhysodidae). Their moniliform antennae consist of a scape, pedicel, and nine flagellomeres. We identified seven different types of sensilla, according to their morphological characteristics: two types of sensilla chaetica (sc1 and 2), two types of sensilla basiconica (sb1 and 2), one type of sensilla campaniformia, one type of sensilla coeloconica, and Böhm sensilla. No sexual dimorphism was found regarding antennal morphology and sensilla type and distribution, except for the sensilla coeloconica. The functional role of these sensilla was discussed in relation to their external structure and distribution, and compared with the current knowledge on coleopteran sense organs. Results are basic information for further physiological and behavioral studies to identify their role in the selection of habitat, food, mates and oviposition sites.

Sensory structures on the antenna of soldier and worker castes of the termite species Odontotermes parvidens (Termitidae: Isoptera: Blattaria).

Odontotermes parvidens is a commonly found important pest species of termite that primarily feed on a range of cellulosic sources. In termites, communication among the nestmates is the basis of all their daily activities and the sensory structures present on the sensory appendages play a crucial role in different social behaviors perceiving and processing various signals of the nestmates and external environments. So, it is essential to understand in detail their sensory structures in order to understand the sensory system of the species O. parvidens. Thus, we have studied the antenna which is one of the primary sensory appendages of both soldier and worker individuals of the species to elucidate various antennal sensory structures and their distribution using scanning electron microscopy. Based on the morphological features of various sensilla, we observed seven types of sensilla as sensilla chaetica (subtypes I, II, III, and IV), sensilla trichodea (subtypes I and II), sensilla trichodea curvata (subtypes I and II), sensilla basiconica, sensilla capitula, Böhm bristles, and sensilla campaniformia (subtypes I and II) along with numerous glandular pores on the antenna of soldier and worker castes. We have also discussed the putative functions of all the sensilla observed based on their external morphology and distributional characteristics on the antenna of soldier and worker castes of the species O. parvidens. Furthermore, the abundance of sensillar types on the antenna of both the castes has also been discussed.

Observation of the fine structure of antennal sensilla of the stink bug, Eocanthecona furcellata (Hemiptera: Pentatomidae)

In order to explore the mechanism underlying chemosensation in Eocanthecona furcellata, the external morphology of its antennae and the type, quantity, distribution and ultrastructure of the sensilla were observed on both sexes of adults and 5th-instar nymphs using scanning electron microscopy. The results showed that the antennae of E. furcellata consisted of three parts: scape, pedicel and flagellum. There were five types of sensilla on the antennae, which included sensilla trichoidea (ST), sensilla chaetica (SCh), sensilla coeloconica (SCo), sensilla basiconica (SB) and squamifornia denticles (SD). Further, there were 4 subtypes of ST and SB and 2 subtypes of SCo and SCh. The number of sensilla on nymphs was significantly lower than that on adults. The antennae of adults showed sexual dimorphism, as the number of sensilla on female adults was higher than that on male adults. SB4 was found only on females and SCo2 was found only on males. These inter-sexual differences may be related to chemoreception of sex pheromone and chemical predation location. The morphology and putative functions of each sensilla were compared and discussed. These results provide a reference for further study of the behavioral biology, chemical ecology and electrophysiology of insects, and also provides a scientific basis for new ways of biological control.

Sensory structures on the larval antennae and mouthparts of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

The present study is, to the best of our knowledge, the first descriptive research focusing on the structure of the larval gustatory and olfactory sense organs of the tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), using scanning electron microscopy. Various sensilla types were identified and their mean lengths were determined. Three types of sensilla were observed on the pedicel of the antenna: sensillum trichodeum, sensillum chaeticum, and sensillum basiconicum. Subsequently, three sensilla basiconica and one sensillum styloconicum were reported on the flagellum. Mouthparts carried six types of sensilla at various sites. Six pairs of sensilla chaetica and a pair of epipharyngeal setae were located on the labrum. On the maxillae, the cardo bore one sensillum chaeticum while the galea carried two pairs of sensilla basiconica and one pair of sensilla styloconica. The maxillary palp carried eight short sensilla basiconica, sensillum digitiformium, and sensillum placodeum. The labial palp bore long sensillum styloconicum and short chaeticum. The findings provide useful information that may help to understand the olfactory and gustatory perceptions that influence larval preferences for plants as a source of food.

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.

Integration of morphological and molecular taxonomic characters for identification of Odontoponera denticulata (Hymenoptera: Formicidae: Ponerinae) with the description of the antennal sensilla

Integration of morphological and molecular approaches is nowadays given importance to identify a particular species. So in our study, we considered both approaches to identify the controversial ant species, Odontoponera denticulata. For morphological analysis, we considered morphological characters and morphometric measurements. In the molecular approach, we considered DNA barcoding from the COI gene. A nucleotide sequence of 641 base pairs was obtained which showed 86.08% similarity with Odontoponera transversa. No COI gene sequence of O. denticulata is found to exist in Genbank. But morphological characters supported the identity of the species as O. denticulata. Therefore, the sequence obtained was submitted to NCBI Genbank (accession number MN380424). From the study, it can be inferred that the combination of both the morphological and molecular approaches is helpful to identify a species, here in this case the Ponerine ant, O. denticulata. As there is no report on antennal sensilla of O. denticulata, therefore we also investigated the morphology and distribution of antennal sensilla of O. denticulata. Nine different types of antennal sensilla are recorded including Böhm Bristles (BB1, BB2), Sensilla Trichodea (ST1, ST2), Sensilla Chaetica (SCh), Sensilla Basiconica (SB1, SB2), Sensilla Coeloconica (SCo) and Sensilla Campaniformia (SCa). ST1 is the most abundant antennal sensilla found in O. denticulata.

Morphology of egg and larva of the lawn cutworm Spodoptera depravata (Butler) (Lepidoptera: Noctuidae)

Spodoptera depravata (Butler) is an important lawn pest in northeastern Asian countries, and its larvae mainly target the leaves of Gramineae crops. However, the morphological traits of egg and larva of this species have not been well elucidated. In this study, we examined the external morphology and ultrastructure of egg and larva of S. depravata using light and scanning electron microscopy. The egg is subspherical and covered with abundant female hair silk (modified scales). The upper exochorion sculpture consists of a dense network of irregular contiguous polygonal cells, with 2–3 micropyles at the top. Three types of sensilla were observed on larval antenna and maxilla: sensilla chaetica, sensilla basiconica and sensilla styloconica. The larva, eruciform, bears three pairs of thoracic legs, and five pairs of prolegs on abdominal segment III to VI and X (anal prolegs), respectively. The crochets of prolegs are arranged in uniordinal mesal penellipse, and protected by membranous stripes. Besides, the head and body chaetotaxy of S. depravata were illustrated and described in detail. This study also briefly discussed the application of morphological traits of eggs and larvae to classification and systematic studies on Spodoptera species.

The Adelphocoris lineolatus OBP4: Support for evolutionary and functional divergence of a mirid pheromone-binding protein from that found in lepidopteran moths.

Pheromone-binding proteins (PBPs) have been extensively investigated in lepidopteran moths, but their evolution and function in hemipteran species remain unclear. Our previous study demonstrated that an odorant-binding protein, OBP4, of the mirid bug Adelphocoris lineolatus functions as a candidate hemipteran PBP but clustered with lepidopteran antennae-binding proteins (ABPs) rather than in the PBP/general odorant-binding protein (GOBP) clade. In this study, we hypothesized that origin and function of PBPs in hemipteran bugs may differ from those of lepidopteran moths. To test this hypothesis, we first constructed a phylogenetic tree using insect OBPs from sister hemipteran and holometabolous lineages, and the results indicated that neither OBP4 nor other types of candidate PBPs of mirid bugs clustered with the lepidopteran PBP/GOBP clade. Then, a fluorescence competitive binding assay was employed to determine binding affinities of recombinant OBP4 protein to host plant volatiles, with functional groups different from A. lineolatus sex pheromone components. The results revealed that OBP4 highly bound the female adult attractant 3-hexanone and 15 other mirid bug biologically active plant volatiles. Finally, we examined cellular expression profiles of OBP4 in putative antennal sensilla that are related to female A. lineolatus host plant location. The fluorescence in situ hybridization and immunocytochemical labeling assay showed that the OBP4 gene was highly expressed in the multiporous olfactory sensilla medium-long sensilla basiconica rather than in the short sensilla basiconica or uniporous sensilla chaetica. These results, together with those of our previous studies, indicate that OBP4 not only functions in recognition of bug-produced sex pheromones in males, but is probably involved in detection of host plant volatiles in both A. lineolatus sexes. Our findings support the hypothesis that the origin and function of PBPs in hemipteran bugs differ from those of well-known PBPs in lepidopteran moths, which provides a novel perspective on evolutionary mechanisms of sex pheromone communication across insect orders.

Ultrastructure of antennal sensilla of Copidosomopsis nacoleiae (Eady) (Hymenoptera: Chalcidoidea: Encyrtidae), a parasitoid of Diaphania angustalis (Snellen) (Lepidoptera: Crambidae).

The antennal sensilla of Copidosomopsis nacoleiae (Eady) (Hymenoptera: Chalcidoidea: Encyrtidae) were observed under scanning and transmission electron microscopy in this study. The antennae of C. nacoleiae are geniculate, and the flagellum is composed of five subsegments in males and six in females. Six types of sensilla were observed, including sensilla trichodea, sensilla chaetica, sensilla basiconic capitate pegs, sensilla placodea, sensilla basiconica, and Böhm's bristles. Sensilla trichodea were evenly distributed throughout the antennae. Sensilla chaetica, sensilla basiconic capitate pegs and sensilla placodea were found on the flagellomeres. Sensilla basiconica were only found on the club, and Böhm's bristles were found on the radicle and the pedicel. Sensilla trichodea, sensilla placodea, sensilla chaetica, and sensilla basiconic capitate pegs were found to be the most common sensilla of the parasitoids in the superfamily Chalcidoidea. The external and internal characteristics, types, number, distribution, and dimensions of these sensilla are described, and their possible functions are discussed in accordance with host-detection behavior. Future studies on the host location mechanisms of C. nacoleiae will be based upon these observations.

SCANNING ELECTRON MICROSCOPIC INVESTIGATING DIFFERENT TYPE OF SENSORY SENSILLAE ON THE HEAD APPENDAGES OF ASIAN TIGER MOSQUITO, AEDES ALBOPICTUS (SKUSE)

In Aedes albopictus various types of sensillae were on the head and its appendages with distinctmorphological features. The antennae and maxillary palps play a major role in host detection,and other sensory-mediated behaviors. Six long sensilla chaetica were arranged in circularshape and spread uniformly across the diameter of the antennal flagellomers. Maxillarypalp is a relatively simple organ compared to antennae, consists of five segments, which denselycovered dorsal side with flattened scales, but chemosensory sensilla on ventral side. Thus,a desirable model for exploring neuromolecular networks surrounds chemo- and mechanosensation.Proboscis analyses gustatory code via food intake and involved in identification. Labellumexhibits the most of sensory structures on the proboscis. Numerous sensillatrichoidea distributeon antennal flagellomers.A significant difference in diameter of sensillacoeloconica that protruding from distal tip ofantennal flagellomers. Sensillachaetica with greater morphological variation were distributedthroughout Ae. albopictus head and appendages. Variation between different sensillae indicatestheir functions. Aporous sensilla play the mechanoreceptive role but, porous sensillawere contact chemoreceptors and olfactory ones. sensory mechanisms were extensivestudied, about Asian tiger mosquito, Ae. albopictus sensory systems is insufficient.

Ultra structural study on different sensory structure and some associated body parts of mango mealy bug, Drosicha mangiferae (G.) by scanning electron microscopy

Ultra structural study on different sensory structure and some associated body parts of mango mealy bug, Drosicha mangiferae (G.) by scanning electron microscopy