Antennal Sensilla Research Articles

Three new species of the genus Philagra Stål (Hemiptera: Cercopidea: Aphrophoridae) from China and Bangladesh

Three new species of Philagra Stål, P. bimaculata sp. nov., P. fuscofasciata sp. nov. and P. straminea sp. nov. are described and illustrated from China with P. bimaculata sp. nov. also recorded from Bangladesh. Morphological descriptions and structural illustrations of the new species are provided with distributional data given. Scanning electron micrographs of antennal sensilla of P. bimaculata sp. nov. and P. straminea sp. nov. and sensilla on rostral apex of P. bimaculata sp. nov. are provided for the first time.

Attraction of Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae) to Host Plant Cucurbita maxima Duchesne (Cucurbitaceae) Volatiles

The volatiles extracted by the dynamic headspace collection system from the undamaged and conspecific damaged Cucurbita maxima were analyzed by Gas chromatography–mass spectrometry (GC-MS). The olfactory responses of antennal chemosensilla by male and female A. foveicollis towards the plant volatiles were studied by electroantennography (EAG), while the behavioral responses were analyzed by olfactometer bioassay under laboratory conditions. Scanning electron microscopic study revealed the predominance of antennal olfactory sensilla of seven different types with four types of mechanosensilla. The antennae are sexually dimorphic, with differences in density of the chemosensillae present in the apical band region of segment IX, called the circumferential band, being higher in the females. Female antennae showed maximum peak amplitudes for 2-methyl phenol (at 10 mg/mL), followed by 1,4, dimethoxybenzene (at 5 mg/mL), while male antennae showed maximum amplitudes for heneicosane (at 5 mg/mL). Y-tube bioassays revealed maximum attractiveness towards 1,4, dimethoxy benzene that decreased progressively across heneicosane, pentacosane, tetradecane, ethyl benzene, D-limonene, nonadecane, eicosane, nonanal, decanal, α-pinene, phytol and benzaldehyde in females. However, male species were more responsive towards heneicosane, followed by 1,4 dimethoxybenzene, while the responses to pentacosane and tetradecane were equal, followed by equal responses to decanal, ethyl benzene and nonadecane, and thereafter, a progressively reducing response was observed towards α-pinene, eicosane, nonanal, D-limonene, phytol and benzaldehyde. The study assists in understanding the role of olfaction by A. foveicollis in the host plant Cucurbita maxima by listing compounds that act as potential kairomones for the beetle, and can be expected to facilitate development of an eco–friendly trap and/or by attracting the natural enemies for control of the pest.

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.

Insights into the Antennal Characteristics and Olfactory Strategy of the Endangered Rhino Stomach Bot Fly Gyrostigma rhinocerontis (Diptera: Oestridae).

Simple SummaryGyrostigma rhinocerontis (Hope), the rhinoceros bot fly, is a rare obligate intestinal parasite of white and black rhinoceroses that can cause severe myiasis and secondary infection, leading to enormous economic and scientific loss. As the main sensory organs of flies, the antennae provide insects with critical information about the environment, playing significant roles in their key activities. The antennal characteristics of G. rhinocerontis remain largely unexplored, probably due to the extreme rarity of adult specimens in collections. In this study, the antennae of G. rhinocerontis were thoroughly examined using light and scanning electron microscopy. The morphology, including detailed ultrastructure, of antennal sensilla are presented. As the largest species of Oestridae Leach, not surprisingly, G. rhinocerontis has significantly larger antennae with more sensilla and sensory pits than any other Oestridae species, which could be an adaptation to locate their rare and endangered hosts.Gyrostigma rhinocerontis (Diptera: Oestridae) is a rare obligate intestinal parasite of both white and black rhinoceroses, which can induce severe myiasis, cause secondary infection, and lead to enormous economic and scientific loss. Antennae are the main sensory organs of G. rhinocerontis, which may have evolved a series of specialized adaptive structures to facilitate the exploitation of their hosts. Here, we thoroughly examine the antennae of G. rhinocerontis via light and scanning electron microscopy. Only microtrichia and chaetic sensilla were observed on the scape and pedicel, and the latter is enlarged, half-enveloping the postpedicel. Four types of sensilla (trichoid sensilla, basiconic sensilla, coeloconic sensilla, and clavate sensilla) and sensory pits are detected on the postpedicel. A set of coeloconic sensilla and a chaetic sensillum are located on the arista. Distribution, type, size, and ultrastructure of antennal sensilla are presented. The antennae of G. rhinocerontis are the largest among Oestridae species, with the most sensilla and the most sensory pits. These antennal characteristics could be correlated to their adaptation for more sensitive and accurate olfactory organs, used to locate their rare and endangered hosts. Accordingly, this morphological evidence supports that the host is an important driving factor in the diversity of antennal morphology in the bot flies.

Comparative Morphogenesis of Antennal Sensilla Between the Leptocybe invasa and Ophelimus maskelli (Hymenoptera: Eulophidae) and its relationship to their vital Capacity

Comparative Morphogenesis of Antennal Sensilla Between the Leptocybe invasa and Ophelimus maskelli (Hymenoptera: Eulophidae) and its relationship to their vital Capacity

Olfaction in phytophagous ladybird beetles: antennal sensilla and sensitivity to volatiles from host plants in Chnootriba elaterii

Olfaction and chemical ecology in phytophagous ladybird beetles have been largely ignored so far. The present paper describes for the first time basiconic, grooved, and trichoid porous olfactory sensilla on the antennae of the phytophagous ladybird Chnootriba elaterii (Epilacnini) and demonstrates the sensitivity of the antennae to Volatile Organic Compounds (VOCs) from host plants, belonging to common and less common Cucurbitaceae crops and wild species (Citrullus lanatus, Cucumis melo, Cucumis sativus, Cucurbita pepo, Cucurbita moschata, Lagenaria siceraria, Luffa cylindrica, and Ecballium elaterium). Epilachnini ladybirds are phytophagous, with adult and larvae feeding on various Cucurbitaceae, Fabaceae, and Solanaceae. Notwithstanding some species are serious pests in crops, their chemical ecology has been largely disregarded so far. The present paper discusses the ultrastructure of antennal sensilla (scanning electron microscopy-SEM) and the electroantennographic recordings (EAG) from the olfactory sensilla responding to the proposed chemicals, also considering the literature on chemical ecology and olfaction of aphidophagous ladybugs. In particular, antennal sensilla are similar to those described in predatory species but in Epilachnini they are much more numerous on the apical flagellum, probably because involved in host plant location and selection. This research can be considered a first step in developing semiochemical-based and sustainable control strategies for melon ladybird in crops.

Revisiting trends in morphology of antennal sensilla in scarabaeoid beetles

Phytophagous scarab beetles associated with angiosperms have characteristically enlarged lamellate antennae and exhibit a striking morphological variation of sensilla. In this study, we compared the morphology of antennal surface of 62 species Scarabaeoidea using SEM microscopy, particularly also in light of their evolution in association with angiosperms. We investigated the correlation of antennal sensilla morphology, i.e., their structure and distribution, with species diversity and lineage diversification rates. A high diversity of sensilla was observed but also multiple transitional forms, even on the same antennomere. We interpreted this as evidence for a high evolutionary plasticity. We recognized clear patterns of convergence and repeated evolution of certain types of placoid sensilla. One main tendency found in the phytophagous Pleurostict chafers was a shift from sensilla trichodea to placoid-like sensilla, apparently also enhanced by the increase of the lamellate antennal surface, either by size or number of the lamellae. This trend occurred not only in the Pleurosticts, but also in Glaphyridae, a second angiosperm-associated lineage of Scarabaeoidea. However, our results suggest no direct relation between species diversity or the rate of diversification and general sensilla morphology, i.e., the origin of placoid sensilla. This could be explained not only by species-poor lineages also possessing placoid sensilla but also by otherwise successful and species rich groups having sensilla trichodea (e.g., dung beetles). Results further reveal the need to refine current phylogenetic hypotheses by more comprehensive taxon sampling and to expand the molecular characterization of pheromones and odor binding proteins to better understand the role of chemical communication in scarab diversification.

Ultra-Morphology and Mechanical Function of the Trichoideum Sensillum in Nabis rugosus (Linnaeus, 1758) (Insecta: Heteroptera: Cimicomorpha)

Simple SummaryNabis rugosus is a representative of the Nabidae family belonging to the heteropteran group. It is a predator of tiny insects and has different sensory receptors that detect environmental changes. The present study focuses on the antennal sensilla of N. rugosus, mainly on the trichoideum sensillum as mechanoreceptors for detecting various tactile factors surrounding the insect. The morphology of trichoideum mechanosensillum in N. rugosus was modelled as a three-dimensional structure from the derived data sets using SEM and TEM. Specific inner features of the sensillum are also presented, which will be useful to build a biosensor for detecting physical environmental parameters.The present study aims to investigate the morphological features of the antennal sensilla by using SEM and TEM. The construction of a 3D model of trichoideum sensillum using Amira software is presented in this paper. Five sensillum types, namely trichoideum, chaeticum, campaniformium, coeloconicum, and basiconicum, were recorded. This model exhibits the mechanosensillum components, including the embedded hair in a socket attached by the joint membrane and the dendrite connected to the hair base passing through the cuticle layers. TEM images present the dendrite way, micro-tubules inside the dendritic sheath, and terminal structure of the tubular dendrite body and so-called companion cells included in the receptor, e.g., tormogen and trichogen. The parameters noted for the external structure and ultrastructure of the mechano-receptor indicate that they are specific to a particular type of sensillum and would be useful in developing the model for a biosensor. Results show that bio-inspired sensors can be developed based on morphological and ultrastructural studies and to conduct mechanical studies on their components.

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.

Comparative morphology of antennal ultrastructure in Tachinidae parasitoid flies (Diptera): The phylogenetic importance of antennal sensilla

Tachinidae are one of the most diverse clades of Diptera. All tachinids are parasitoids of insects and other arthropods, and thus are considered an important source of biological pest control. Antennae are the most important olfactory organs of Tachinidae playing key roles in their lives, especially in locating hosts, and details of antennal ultrastructure could provide useful features for phylogenetic studies and understanding their adaptive evolution. Despite the ecological and evolutionary importance of antennae, the current knowledge of antennal ultrastructure is scarce for Tachinidae. Our study examined antennal sensilla of thirteen species belonging to thirteen genera within eleven tribes of all the four subfamilies (Phasiinae, Dexiinae, Tachininae, and Exoristinae): Beskia aelops Walker, Trichodura sp., Voria ruralis (Fallén), Zelia sp., Cylindromyia carinata Townsend, Phasia xenos Townsend, Neomintho sp., Genea australis (Townsend), Copecrypta sp., Hystricia sp., Belvosia sp., Leschenaultia sp., and Winthemia pinguis (Fabricius). Types, length and distribution of antennal sensilla were investigated via scanning electron microscopy (SEM). Our comparative analysis summarized 29 variable characters and we evaluated their phylogenetic signal for subfamilial, tribal and generic/specific levels, showing that antennal ultrastructure could be a reliable source of characters for phylogenetic analysis. Our findings demonstrate the remarkable diversity of the antennal ultrastructure of Tachinidae.

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.

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.

Sensory plasticity in a socially plastic bee.

The social Hymenoptera have contributed much to our understanding of the evolution of sensory systems. Attention has focussed chiefly on how sociality and sensory systems have evolved together. In the Hymenoptera, the antennal sensilla are important for optimizing the perception of olfactory social information. Social species have denser antennal sensilla than solitary species, which is thought to enhance social cohesion through nestmate recognition. In the current study, we test whether sensilla numbers vary between populations of the socially plastic sweat bee Halictus rubicundus from regions that vary in climate and the degree to which sociality is expressed. We found population differences in both olfactory and hygro/thermoreceptive sensilla numbers. We also found evidence that olfactory sensilla density is developmentally plastic: when we transplanted bees from Scotland to the south‐east of England, their offspring (which developed in the south) had more olfactory hairs than the transplanted individuals themselves (which developed in Scotland). The transplanted bees displayed a mix of social (a queen plus workers) and solitary nesting, but neither individual nor nest phenotype was related to sensilla density. We suggest that this general, rather than caste‐specific sensory plasticity provides a flexible means to optimize sensory perception according to the most pressing demands of the environment. Sensory plasticity may support social plasticity in H. rubicundus but does not appear to be causally related to it.

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.

The Antennal Sensilla and Expression Patterns of Olfactory Genes in the Lower Termite Reticulitermes aculabialis (Isoptera: Rhinotermitidae).

The insect olfactory system plays pivotal roles in insect survival and reproduction through odor detection. Morphological and physiological adaptations are caste-specific and evolved independently in workers, soldiers, and reproductives in termites. However, it is unclear whether the olfactory system is involved in the division of labor in termite colonies. In the present study, the antennal sensilla of alates, workers, soldiers, nymphs, and larvae of the termite Reticulitermes aculabialis Tsai et Hwang ( Isoptera: Rhinotermitidae) were investigated. Transcriptomes were used to detect olfactory genes, and differential expression levels of olfactory genes were confirmed in various castes by qRT–PCR analysis. Nine types of sensilla were identified on the antennae of R. aculabialis, and soldiers possessed all 9 types. In 89,475 assembled unigenes, we found 16 olfactory genes, including 6 chemosensory protein (CSP) and 10 odorant-binding protein (OBP) genes. These OBP genes included 8 general odorant-binding protein genes (GOBPs) and 2 pheromone-binding protein-related protein (PBP) genes. Five CSP genes were more highly expressed in alates than in workers, soldiers, larvae, and nymphs, and the expression levels of CSP6 were significantly higher in nymphs. Seven GOBP and two PBP genes exhibited significantly higher expression levels in alates, and there were no significant differences in the expression levels of GOBP2 among workers, soldiers, alates, and larvae. These results suggest that alates, as primary reproductives, have unique expression patterns of olfactory genes, which play key roles in nuptial flight, mate seeking, and new colony foundation.

Ultrastructure of Antennal Sensory Organs in Nine Flesh Flies (Diptera: Sarcophagidae): New Insight into the Definition of Family Sarcophagidae

Simple SummaryThe antennal sensilla of species in all three subfamilies of Sarcophagidae are studied for the first time via scanning electron microscopy. The morphology, density, and distribution of each type are described for each species. A total of eight types of antennal sensilla (chaetic sensilla, setiferous plaques, pedicellar buttons, trichoid sensilla, basiconic sensilla, coeloconic sensilla, clavate sensilla, bottle-shaped sensilla) and sensory pits are found in both sexes. The existence of bottle-shaped sensilla in the sensory pits in all three subfamilies of the sarcophagid species suggests a potential synapomorphy of sarcophagids and a new morphological diagnosis character of the family Sarcophagidae.The antennae are the main olfactory organ of flies, playing key roles in their survival and the success of all life stages. Antennal ultrastructural morphology has been well described in the representative species of most calyptrate families, yet only a few studies have focused on Sarcophagidae species, those with ecological and medical relevance. Antennal morphology and the types, shapes, distribution, and density of the antennal sensilla of nine Sarcophagidae species are studied in detail with scanning electron microscopy, including Miltogramminae: Metopia campestris (Fallén) and Mesomelena mesomelaena (Loew), Paramacronychiinae: Agria mihalyii (Rohdendorf & Verves), Wohlfahrtia bella (Macquart), and W. magnifica (Schiner); Sarcophaginae: Sarcophaga (Parasarcophaga) albiceps Meigen, S. (Bercaea) africa (Wiedemann), S. (Boettcherisca) peregrina (Robineau-Desvoidy), and S. (Liosarcophaga) portschinskyi (Rohdendorf), covering all three subfamilies of this family. The morphology of the three segments of the antennae has been described. The scape has only one type of chaetic sensilla, while three subtypes of chaetic sensilla were detected on the pedicel. The postpedicel has four types of sensilla: trichoid sensilla, coeloconic sensilla, clavate sensilla, and three subtypes of basiconic sensilla. Bottle-shaped sensilla were observed in sensory pits on the postpedicel in all nine species. These sensilla have not been discovered in other calyptrate species, suggesting that they are a potential sarcophagid synapomorphy.

Abnormal Antennal Olfactory Sensilla Phenotypes Involved in Olfactory Deficit in Bactrocera correcta (Diptera: Tephritidae).

Simple SummaryTephritidae fruit flies sense odorants mainly through antennal olfactory sensilla with nanopores. Therefore, theoretically, the development of nanopore-targeted pest control technologies is an important direction in the future. Here, we report naturally occurring abnormal antennal trichoid and basiconic olfactory sensilla phenotypes consisting of abnormal bulges and reduced nanopore numbers in a long-term laboratory rearing colony of the guava fruit fly Bactrocera correcta, and further find that the reduction of nanopore numbers in these sensilla led to an olfactory deficit. Our findings provide a basis for developing nanopore-targeted pest control technologies in the future.The guava fruit fly, Bactrocera correcta, is one of the most destructive pests in the genus Bactrocera and detects environmental odorants mainly through antennal olfactory sensilla phenotypes with nanopores. However, it is unclear whether there are naturally occurring abnormal antennal olfactory sensilla phenotypes that affect olfaction. Here, we found that there were abnormal bulges besides nanopores on the surface of trichoid and basiconic olfactory sensilla in the antennal flagellum of long-term laboratory rearing colony (LTC), and that nanopore number in these olfactory sensilla was also remarkably reduced. Notably, the electroantennogram (EAG) responses of LTC insects to methyl eugenol or β-caryophyllene were inhibited, and their behavioral responses elicited by the same odorants were also impaired. These results revealed naturally occurring abnormal antennal olfactory sensilla phenotypes which were involved in olfactory deficit in B. correcta, providing a platform to further study nanopore-targeted pest control technologies in the future.

Report on antennal sensilla of Aphelocheirus ellipsoideus (Hemiptera, Heteroptera, Aphelocheiridae).

The comparative morphology study on antennal sensilla of Aphelocheirus ellipsoideus from the family Aphelocheiridae, carried out with the use of a scanning electron microscope, is provided. Five main types of mechano-, chemo-, and thermo-hygroreceptive sensilla with two subtypes of sensilla basiconica were found and described on their surface, including sensilla trichodea, campaniformia, basiconica, ampullacea, and plate-like. Antennal sensilla of A. ellipsoideus on macropterous and brachypterous forms were different.

Antennal Sensilla in Vespidae: A Comparison Between a Diurnal and a Nocturnal Polistinae Wasp.

Social wasps have a widespread Neotropical distribution and are important pollinators and biological control agents for pest insects. The foraging activity of wasps is influenced by biotic and abiotic factors that are detected by the antennal sensilla that vary according to species, sex, caste, and environmental conditions. This study compares the types and quantities of antennal sensilla with a scanning electron microscope between the nocturnal Apoica flavissima and the diurnal Polistes simillimus wasps. Six types of sensilla were found in the antennae of both species: placoid, coeloconic, basiconic-type 1, basiconic-type 2, trichoid-type 1, and trichoid-type 2. Sensilla chaetica were found only in the scape and pedicel of A. flavissima. In the nocturnal wasp, there are 19,132.27 ± 1,247.72 sensilla in the left and 17,746.46 ± 1,477.46 in the right antennae, whereas in the diurnal wasp 14,936.72 ± 1,271.69 in the left and 16,090.82 ± 1,345.3 in the right antennae. A. flavissima has a longer antennal length and number of sensilla than P. simillimus. The higher number of antennal sensilla in the nocturnal wasp is not linked with the antennal size. The association of antennal sensilla functions with ecological and behavioral factors of A. flavissima and P. simillimus are discussed.

Functional morphology of mouthparts and antennal sensillae of two co-generic aphidophagous ladybirds

Functional morphology of mouthparts and antennal sensillae of two co-generic aphidophagous ladybirds