Sensilla Auricillica Research Articles

Morphological characterization and distribution of antennal sensilla of Spodoptera frugiperda (Lepidoptera: Noctuidae) using scanning electron microscopy.

The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a globally significant agricultural pest, causing severe damage to corn production in China. Chemical odor-based trapping is a major approach for FAW control, making it essential to understand the FAW antennal sensillum types to enhance development of effective chemical odor attractants. In this study, we comprehensively examined the antennal sensilla types of FAW, identifying eight types and two subtypes, including Böhm's bristles, sensilla trichoidea, sensilla chaetica (I and II), sensilla coeloconica, sensilla styloconica, sensilla squamiformia (I and II), sensilla auricillica, and sensilla basiconica. Sensilla chaetica II, and sensilla squamiformia II are reported for the first time for FAW in this study. Detailed low-voltage field emission scanning electron microscope (LVSEM) images and descriptions are provided for each sensillum type. This study provides the morphological information to aid in conducting antennal sensillum neurophysiological tests on FAW. RESEARCH HIGHLIGHTS: The types of sensilla of fall armyworm were examined, identifying eight types and two subtypes, including Böhm's bristles, sensilla trichoidea, sensilla chaetica (I and II), sensilla coeloconica, sensilla styloconica, sensilla squamiformia (I and II), sensilla auricillica, and sensilla basiconica. Detailed low-voltage field emission scanning electron microscope images and descriptions were provided for each sensillum type.

Morphology and distribution of sensilla on antennae and mouthparts of the adult bruchid beetles, Bruchidius coreanus (Coleoptera: Bruchidae).

Bruchidius coreanus is a serious pest on Gleditsia sinensis Lam during seed storage, causing significant losses to their yield in southwest China. To gain insight into their behavioral mechanisms, the external morphology, ultrastructure, and distribution of sensilla on antennae, maxillary palps, and labial palps of both male and female B. coreanus were observed using a scanning electron microscope. The results revealed that both male and female adults had serrated antennae comprising a scape, a pedicel, and nine flagellomeres (F1-F9). There were eight types and seven subtypes of antenna sensilla observed in both sexes, including Böhm sensilla (BS), two subtypes of sensilla chaetica (SC1 and SC2), two subtypes of sensilla trichodea (ST1 and ST2), three subtypes of sensilla basiconica (SB1, SB2, and SB3), sensilla auricillica (SA), sensilla styloconicum (SS), capitate pegs (CP), and sensilla cavity (SCa). The average length of BS and ST (ST1 and ST2) showed significant differences between males and females. Furthermore, the number of SC (SC1 and SC2), ST1, and SCa differed significantly between the sexes. Four types of sensilla were found on the maxillary palps and labial palps, with the length of ST on these palps significantly differing between males and females. Additionally, SS on male labial palps was significantly longer than in females. The number of SC significantly differed between the male and female maxillary palps and labial palps, while ST and SS showed significant differences in the maxillary palps. These findings will contribute to further electrophysiological recording and behavioral research. RESEARCH HIGHLIGHTS: The external morphology and distribution of various sensilla on the antennae, maxillary palps, and labial palps of Bruchidius coreanus were described. Eight types and seven subtypes of antenna sensilla were observed on the antennae, while four types of sensilla were observed on the maxillary palps and labial palps. The capitate pegs were found exclusively on the antennae of female B. coreanus.

Morphology and Distribution of Antennal Sensilla on Spodoptera frugiperda (Lepidoptera: Noctuidae) Larvae and Adults

The invasive pest, Spodoptera frugiperda, commonly known as the fall armyworm (FAW), is a serious threat to food security in multiple countries worldwide. Insects’ antennal sensilla play a crucial role in perceiving plant odors and communication between male and female insects. This study aimed to examine the antennal morphology and sensilla variations on the antennae of FAW larvae and adults through scanning electron microscope analysis. The results revealed that third and fifth instar larval antennae possessed smell pores, sensilla pegs, and five types of antennal sensilla, namely sensilla trichodea, sensilla basiconica, sensilla chaetica, sensilla campaniform, and sensilla styloconicum, and the smell pores were first observed in Lepidoptera larvae. Furthermore, the size of sensilla in fifth instar larvae was significantly greater than those in third instar. On the adult antennae, there were smell pores and 12 types of sensilla identified: sensilla trichodea, sensilla basicaonica, sensilla auricillica, sensilla cavity, sensilla placodea, sensilla ligulate, Böhm’s bristles, sensilla chaetica, sensilla squamous, sensilla coeloconica, sensilla styloconicum, and sensilla uniporous peg. Notably, the sensilla cavity, sensilla placodea, sensilla ligulate, sensilla uniporous peg, and smell pores were first discovered in FAW adults. Compared with larvae, FAW adults have more types and amounts of sensilla. Additionally, we also discussed the possible functions of these antennal sensilla. This study provides valuable information for a comprehensive understanding of the type and function of antennal sensilla in FAW and assists in the development of novel pest control strategies, such as pest behavior control technology, for the prevention of this invasive pest.

Morphological Characterization of the Antennal Sensilla of the Legume Pod Borer, Maruca vitrata (Fabricius) (Lepidoptera: Crambidae).

Maruca vitrata (Fabricius) is an important lepidopteran pest of legumes in the tropics and subtropics. Here, we studied the ultrastructural organization of its antennal sense organs using scanning electron microscopy. The antennae of both sexes of M. vitrata were filiform with the number of flagellar segments varying from 72 to 84. Nine major morphological types of sensilla were observed on male and female antennae: sensilla trichodea (ST), sensilla basiconica (SB), sensilla auricillica (SA), sensilla chaetica (SCh), sensilla coeloconica (SCoe), sensilla cylindrica (SCy), sensilla squamiformia (SSq), sensilla styloconica (SSt), and Böhm sensilla (BS). Three of these sensilla types (SB, SSq, and BS) are newly reported for M. vitrata. Morphological observations revealed that four types are multiporous (ST, SB, SA, and SCoe), two types are uniporous (SCh and SCy), and three types are aporous (SSq, SSt, and BS). The average length of male ST was longer than that of the female. Sensilla cylindrica were observed only on male antennae, indicating sexual dimorphism. This study aims to provide some basic evidence for further studies on the mechanism of insect-plant chemical communication and future semiochemical-based management strategies of the major legume pest M. vitrata.

Scanning electron microscopy study of the antennal sensilla of cob borer, Stenachroia elongella (Lepidoptera: Pyralidae).

Stenachroia elongella is an important pest of maize in Meghalaya, India. To understand the roles of sensory organs in the biological behaviors of this insect, we determined the structure and distribution of sensilla found on the antenna of both male and female S. elongella by scanning electron microscope. The antenna of both sexes is a filiform type, and the overall length of the female antenna is significantly longer than the male antenna. In both sexes, seven types and two subtypes of antennal sensilla are identified; sensilla trichodea, sensilla chaetica, sensilla styloconica, sensilla coeloconica, sensilla auricillica (I, II), sensilla squamiformia and Böhm sensilla. No sexual dimorphism on the specific occurrence of sensilla is observed. Probable functions are discussed based on their external morphology. These results would be helpful for further studies on TEM investigations, electrophysiological recordings, and behavioral studies. RESEARCH HIGHLIGHTS: Seven types and two subtypes of antennal sensilla were observed in both male and female Stenachroia elongella. Morphology and distribution of the antennal sensilla were discussed. Sexual dimorphism was observed on the overall length of the antenna where the female antenna is longer than the male antenna. No sexual dimorphism was observed on specific occurrences of antennal sensilla.

Antennal Sensilla in Longhorn Beetles (Coleoptera: Cerambycidae)

AbstractInsect antennae are crucial sensory organs that house numerous sensilla with receptors for perceiving a wide variety of cues dominating their world. Historically, inconsistent terminology and criteria have been used to classify antennal sensilla, which has greatly impeded the comparison of data even across closely related species. Longhorn beetles (Coleoptera: Cerambycidae) are no exception to this quandary, and despite their prominent antennae, few studies have investigated their antennal morphology and ultrastructure, and none have compared sensillar diversity and variation among cerambycids. Existing studies of longhorn beetle antennal sensilla include only 29 species in five of the eight cerambycid subfamilies and include misidentified sensilla types and conflicting terminology. As such, it is very difficult to conduct comparative morphological studies of antennal sensilla in longhorn beetles and challenging to understand inter- and intra-specific variation in the sensory systems of these beetles. To facilitate future comparative studies, we reviewed all accessible published papers that have used scanning and transmission electron microscopy (SEM and TEM) to investigate antennal sensilla in cerambycids, and present a first attempt at standardizing the classification of their documented sensilla types and subtypes. Specifically, we discuss seven major types of antennal sensilla (Böhm bristles, sensilla chaetica, chemosensory hairs, sensilla basiconica, dome shaped organs, sensilla coeloconica, and sensilla auricillica). We also imaged the antennae of relevant species of longhorn beetles using SEM and included images exemplifying as many of the sensilla types and subtypes as possible.

Antennal and proboscis sensilla characteristics of Paranthrene tabaniformis (Lepidoptera: Sesiidae).

The poplar clearwing moth, Paranthrene tabaniformis (Lepidoptera: Sesiidae) is a serious wood-boring pest of several trees. The ultramorphology of the antennae and proboscis sensilla of adult P. tabaniformis was examined using scanning electron microscope to determine their structures and sex-specific differences. The results showed that the antennae of both sexes are composed of three segments: scape, pedicel and flagellum. Female antennae are clavate while male antennae are pectinate. The number of flagellomeres for females was significantly greater than for males. Seven different types of sensilla were identified on antennae of both males and females: Böhm sensilla, sensilla squamiformia, sensilla trichodea (three subtypes), sensilla chaetica, sensilla coeloconica, and sensilla auricillica (two subtypes), and apical sensors. Three different types of sensilla were found on the proboscis of adult P. tabaniformis: sensilla styloconica, sensilla chaetica, and sensilla basiconica (three subtypes). The sexual dimorphism difference in the number, distributional pattern, the length and the basal width of various sensilla on the antennae and proboscis were determined. This study clarifies the types and sexual dimorphism of the antennal and proboscis sensilla of adult P. tabaniformis and provides useful theoretical foundations for studies on behavioral mechanisms and functions of sensilla of P. tabaniformis. RESEARCH HIGHLIGHTS: Various types of sensilla on the antennae and proboscis of adults Paranthrene tabaniformis were observed. The sexual dimorphism of various sensilla on the antennae and proboscis were determined.

Morphology and Distribution of Antennal Sensilla in an Egg Parasitoid Wasp, Anastatus disparis (Hymenoptera: Eupelmidae).

The wasp Anastatus disparis is an egg endoparasitoid of a number of Lepidopteran pest species. To better understand the A. disparis olfactory system, we observed the antennal sensilla of males and females under a scanning electron microscope and quantified their sizes and morphological characteristics. We identified the types of sensilla and counted the numbers and locations of the different types on the dorsal and ventral antennal surfaces. The antennae of A. disparis are geniculate, with flagella that comprise 11 subsegments in females and eight in males. The mean antenna length was 1324.10 ± 52.50 μm in females and 1323.93 ± 65.20 μm in males. Ten sensillum types were identified in both sexes: Böhm bristles (BBs), sensilla trichodea (ST, with subtypes STI and STII), sensilla chaetica (SCh), sensilla basiconica (SB, with subtypes SBI and SBII), sensilla placodea (SP), sensilla coeleoconica (SCo), sensilla grooved peg (SGP), sensilla auricillica (SAu), sensilla campaniformia (SCa), and glandular pores (GPs). The total numbers of BBs, STI, SBII, SCa, SCo, and GPs did not differ significantly between the sexes, whereas the total numbers of SCh, SBI, and SAu were significantly greater in females, and those of STII, SP, and SGP were significantly lower. The types, number, and density of antennal sensilla increased from the base to the end. The possible functions of these sensilla in host-detection behavior are discussed.

Functional Morphology of the Antennae and Sensilla of Coeloides qinlingensis Dang et Yang (Hymenoptera: Braconidae).

Simple SummaryThe wasp Coeloides qinglingensis (Hymenoptera: Braconidae) parasitizes insects that damage pine trees, so it is a potential biocontrol agent. Here, we used scanning electron microscopy to examine the fine morphology of the antennae of the adults, as well as the type, shape, and distribution of antennal sensilla. We detected sexual dimorphism in antennal flagellar length, and observed nine morphological types of antennal sensilla. Importantly, dome-shaped sensilla and sensilla auricillica are reported for the first time for C. qinlingensis in this study. Their shape differs from that of sensilla described in other parasitic wasp species. We discuss the potential functions of the sensilla of C. qinlingensis through comparisons with those of sensilla of other parasitic wasps, including braconid wasps that parasitize concealed insect hosts. This information provides a solid foundation for further studies on the chemical communication and behavior of C. qinlingensis.Coeloides qinlingensis Dang et Yang, 1989 (Hymenoptera: Braconidae) is a biocontrol agent of several scolytid pine pests in Southwest China. We examined the fine morphology of the antennae of adult C. qinlingensis, as well as the type, shape, and distribution of antennal sensilla, via scanning electron microscopy. The antennae of female and male C. qinlingensis are filiform and comprise a scape, pedicel, and 31–36 flagellomeres. We detected sexual dimorphism in antennal flagellar length but not in the length of other subsegments. A total of nine morphological types of antennal sensilla varying in cuticular pore structure are present in both sexes, including nonporous types (sensilla trichodea, sensilla chaetica (2 subtypes), and sensilla coeloconica); apical pore types (sensilla basiconica and sensilla auricillica); and multiporous types (dome-shaped sensilla and sensilla placodea (2 subtypes)). Dome-shaped sensilla and sensilla auricillica are reported for the first time for C. qinlingensis, and their shape differs from that of sensilla in other parasitic wasps. The functional morphology of the sensilla of C. qinlingensis was compared with that of the sensilla of other parasitic wasps, including those that parasitize concealed insects. This information provides a foundation for further research on the chemical communication and behavior of C. qinlingensis.

Ultrastructure Characteristics and Sexual Dimorphism of Antennal Sensilla in Tirathaba rufivena (Lepidoptera: Pyralidae).

Simple SummaryTo elucidate the external morphology and internal structures of antennal sensilla that could play a role in locating host plants and mates, we describe and further characterize the ultrastructure, abundance and distribution of nine sensilla types in both sexes using scanning electron microscopy and transmission electron microscopy. Sexual dimorphism mainly occurs in variation in the length of sensilla basiconica, sensilla chaetica, sensilla coeloconica 1 and Böhm sensilla, and the abundance of sensilla basiconica, sensilla auricillica 1 and sensilla auricillica 2. The possible structural function of each kind of sensillum is discussed. These results provide direct morphological evidence that the antennae of Tirathaba rufivena possess structures that can play a role in locating mates and host plants.Tirathaba rufivena Walker, a major insect pest of Areca catechu L., has severely threatened areca nut cultivation in Hainan, China. To improve our understanding of the communication mechanism in host plant seeking and mate-finding for T. rufivena, we described and further characterized the external morphology and internal sensilla structures using scanning electron microscopy and transmission electron microscopy in this study. The antennal morphology was similar between males and females, and there was no significant difference in length between the two sexes. In total, nine sensilla types were identified: sensilla trichodea (Str), sensilla chaetica (Sch), sensilla basiconica (Sba), sensilla auricillica (Sau), sensilla coeloconica (Sco), sensilla styloconica (Sst), Böhm sensilla (Bs), uniporous peg sensilla (Ups) and sensilla squamiformia (Ssq). Sexual dimorphism mainly occurs in variation in the length of Sba, Sch, Sco1 and Bs, and the abundance of Sba, Sau1 and Sau2. The Sba had larger size and numbers on female antennae than that on males, suggesting that these sensilla might have important roles in locating host plants. Both Sau1 and Sau2 were significantly more abundant in females and were probably associated with the detection of mates and host plant for oviposition. These data were important for ongoing studies on host plant seeking and mate-finding behavior in T. rufivena and provided a theoretical foundation to further studies of semiochemical control for this pest.

Scanning electron microscopic studies of the antennal sensilla of Aplosonyx chalybaeus (Hope) (Coleoptera: Chrysomelidae).

Aplosonyx chalybaeus is a major insect pest of the plant Colocasia which is commonly found in the North-Eastern region of India. The antenna of A. chalybaeus is filiform, composed of a scape, a pedicel, and a flagellum with nine flagellomeres. The type, structure, and distribution of sensilla, on the antennae of the adult A. chalybaeus (Coleoptera: Chrysomelidae), were examined by scanning electron microscopy. Eight different types of sensilla were observed on the antennae using scanning electron microscopy, that is, sensilla trichodea, sensilla chaetica, sensilla basiconica, multiporous grooved pegs, sensilla auricillica, sensilla styloconica, glandular plates, and Böhm sensilla based on their external morphology. Distribution of all the antennal sensilla observed was discussed on the antenna. In addition, we discussed the putative functions of all the sensilla observed based on their external morphological and distributional characteristics on the antenna of the species. RESEARCH HIGHLIGHTS: • External morphology and distribution of various antennal sensilla in male and female of Aplosonyx chalybaeus were described. • Eight types with 17 subtypes of antennal sensilla were observed. • Distinct sexual dimorphism was observed in occurrence and distribution of various sensilla.

Morphometrics and distribution of antennal sensillae of both sexes of Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae)

Fall Armyworm, Spodoptera frugiperda, is a devastating invasive pest persisting as a menace hampering the progress of Indian agriculture. The morphometrics and distribution of antennal sensilla of both sexes of S. frugiperda were investigated in the study. The antenna was filiform for both sexes and was composed of scape, pedicel and flagellum. Male antennas had more subsegments (65-71) in the flagellum than female (56-70) antennas. Male and female S. frugiperda antennae possessed eight types of sensilla: sensilla trichoidea, sensilla chaetica, sensilla coeloconica, sensilla styloconica, sensilla basiconica, sensilla auricillica, sensilla squamiformia and Bӧhm’s bristles. Sensilla trichoidea was the most abundant sensilla found in the antenna of both sexes and was more abundant in males than in females. It was also noticed that male antenna was longer than the female antenna. The results of the present study helps to assess alternative management strategies with an electrophysiological response of the pest towards sex pheromones and in combination with plant info chemicals for monitoring and management of S. frugiperda in agricultural ecosystems.

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.

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.

Morphological characterization of antennal sensilla of Earias vittella (Fabricius) (Lepidoptera: Nolidae)

The shoot and fruit borer, Earias vittella Fab. (Lepidoptera: Nolidae) is an important and most devastating insect pest on okra and cotton. The pest mainly responsible for causing significant direct damage to tender shoots and fruits of okra, flowers and green bolls of cotton causing net yield loss in both crops. Many non-chemical control strategies have been developed under the insect pest management program, A complete knowledge on the antennal morphology of E. vitella is essential for future electrophysiological and behavioural studies. In the present study, the antennal morphology and types of sensilla on the antennae of both sexes of E. vitella were examined using light and scanning electron microscopy. Nine distinct types of sensilla were identified on the antennae of both sexes: sensilla trichodea, sensilla basiconica, sensilla coeloconica, sensilla auricillica (multiporous), sensilla chaetica, uniporous peg sensilla (uniporous), sensilla styloconica, sensilla squamiformia and bohm bristles (aporous). Among all sensilla, the most widespread are multiporous sensilla trichodea with 42.90 ± 1.77/flagellomere in male and 37.38 ± 1.38/flagellomere in female. Sensilla basiconica were the second most common sensillum type in male antennae with 15.67 ± 1.92/flagellomere. Other multiporous sensilla such as auricillica (11.90 ± 0.99) and coeloconica (4.57 ± 0.25) were significantly more abundant in female than in male antennae. Results of the study provide morphological evidence that E. vitella antennae possess microscopic cuticular structures that can play a role in perception of pheromones, plant odours and other chemical stimulants. This will open up opportunities to assess the possibility of using pheromones and plant-derived compounds for the monitoring or management of E. vittella moths in the agricultural landscapes.

Ultrastructure of Antennal Morphology and Sensilla of Teak Skeletonizer, Eutectona machaeralis Walker (Lepidoptera: Crambidae).

The leaf skeletonizer, Eutectona machaeralis (Walker) (Lepidoptera: Crambidae), is a severe insect pest of teak trees (Tectona grandis L.f.) in China. To provide some basic evidence for future semiochemical-based management strategies of E. machaeralis, the morphology, ultrastructure, and distribution of antennal sensilla of adults were observed under scanning and transmission electron microscopy. The shape and structure of antenna were similar between males and females, both being filiform. However, the antennal length of males was significantly longer than that of females. Eight morphological sensilla types were observed in both sexes: Böhm's bristles, sensilla trichodea, sensilla basiconica, sensilla chaetica, sensilla styloconica, sensilla coeloconica, sensilla auricillica, and sensilla squamiformia. Significant sexual dimorphism of the sensilla dimensions was found, especially in sensillar length. The putative and potential functions of the different sensilla types are discussed based on the fine structures of the cuticular walls and dendrites of the different sensilla types. We expect these results to help lay a solid foundation for future functional research and develop further investigations of E. machaeralis.

Functional Analysis of Two Odorant-Binding Proteins, MaltOBP9 and MaltOBP10, in Monochamus alternatus Hope.

Odorant-binding proteins (OBPs) are important for the perception of chemical signals by insects. Effective pest management strategies can be developed by understanding the host location mechanism and the physiological functions of OBPs in olfactory detection. In this study, we cloned two OBPs from Monochamus alternatus, where MaltOBP9 was highly expressed in multiple insect tissues and MaltOBP10 was highly expressed in the female antenna according to the results of qRT-PCR. The recombinant proteins were successfully purified in vitro. Immunocytochemistry indicated the high expression of MaltOBP9 and MaltOBP10 in the sensillum lymph of sensilla basiconica, sensilla trichodea, sensilla auricillica, and sensilla chaetica, thereby demonstrating their broad participation in semiochemical detection. Both proteins were localized in the inner cavity of mechanoreceptors and they exhibited broad binding abilities with volatiles from pine bark according to fluorescence competitive binding assays. Due to its broad binding ability and distribution, MaltOBP9 may be involved in various physiological processes as well as olfactory detection. MaltOBP10 appears to play a role in the fundamental olfactory recognition process of female adults according to its broad binding ability. These findings suggest that OBPs may have various physiological functions in insects, thereby providing novel insights into the olfactory receptive mechanism.

Documentation and validation of chemosensory structures in antennae of Spodoptera litura (Fabricius) through Scanning Electron Microscope (SEM)

The studies with SEM clearly depicted that the antenna of female was longer than male antenna. Five types of sensilla namely trichodea, chaetica, styloconica, coeloconica and auricillica, and scales were observed on the flagellum of both sexes. Sensilla trichodea were distributed randomly on all segments and were the most frequent type. Six sensilla chaetica were observed on each flagellar segment in both sexes, except in the apical segment. A sensillum styloconicum was always found at the upper-middle region of each flagellar subsegment. This sensillum had a smooth petiole and a conic extremity with one to three apical structures. Sensilla coeloconica were situated from middle to the distal portion of segment. Sensilla auricillica were found among the scales and had the typical shape of rabbit’s ear. Sensilla squamiformia were present on dorsal part of the antenna among scales. They were shorter and finer than scales and were embedded in a socket and point distally. Sensilla basiconica were smaller and least abundant of all sensilla.

Morphological characterization and distribution of antennal sensilla of Diaphania angustalis Snellen (Lepidoptera: Crambidae).

Diaphania angustalis Snellen (Lepidoptera: Crambidae) is the main defoliator of Alstonia schalaris. In this article, observation of external morphological and ultrastructure structure of adult antennae of D. angustalis was carried out using the scanning and transmission electron microscope. The results showed that both male and female antennae were filiform and could be divided into scape, pedicel, and flagellum. There are eight types and two subtypes of antennal sensilla, namely, sensilla trichodea, sensilla chaetica (I & II), sensilla coeloconica, sensilla auricillica, sensilla styloconica, sensilla squamiformia, capitate peg, and Böhm bristles. Most sensilla are concentrated in venter and the sides of antennae. Analyses on morphological and quantitative differences of antennal sensilla between male and female adults. The size of SCo is significantly different between male and female. In terms of quantity, only SSt and CP have no significant differences between male and female. By comparing the existing antennal sensilla of Crambidae, it is found that STr, SCh, SCo, and SAu are common sensilla. These results can contribute to further research on the function of sensilla of D. angustalis relating to its behavior. A detailed description is provided of the antennal sensilla in Diaphania angustalis. Diaphania angustalis has the rare sensilla of capitate peg in Crambidae. No sexual dimorphism of sensillum types is found in the species. The number and distribution of sensilla trichodea, sensilla chaetica, sensilla coeloconica, and sensilla auricillica sensillum are different.