Morphology and distribution of antennal sensilla of Automeris liberia (Lepidoptera: Saturniidae).

The lepidopteran species Automeris liberia from the Saturniidae family is a polyphagous insect responsible for defoliating plants, such as the oil palm (Elaeis guineensis Jaquim). The antennae of insects play an important role in survival in various environments. Antennae are the main olfactory and sensory organs of insects and have different sensilla to detect chemical cues, movement, humidity and temperature. The olfactory structures present in the antennae are responsible for certain insect behavior, which is influenced by chemical communication. The morphology, distribution and location of the sensilla in the antennae of male and female A. liberia were investigated by scanning electron microscopy to understand the olfactory mechanisms relevant to insect-insect communication and insect-plant communication, among others. The results showed that the flagellum, scape and pedicel length and the number of antennomeres differed between the sexes and demonstrating the existence of sexual dimorphism in the antennae males (bipectinate) and females (filiform). According to the morphological data, seven types of sensilla were identified along the surface of the antennae, classified as trichodea, chaetica, basiconica, coeloconica, squamiformia, styloconica and Böhm's bristles. Among the sensilla chaetica, basiconica and Böhm's bristles, two subtypes based on length were identified in both sexes. The sensilla trichodea exhibited dimorphism since three subtypes were observed in males, while in females, only one subtype was observed, according to the length of the sensilla. Sensilla trichodea subtypes I and II were specific to males, while subtype III was observed in both sexes. These types of sensilla are involved in the recognition of pheromone molecules. Therefore, morphological study of the localization of the sensilla in the antennae will provide useful and relevant results for electrophysiological studies and behavioral tests. This information can help to understand the chemical communication of insects and helps in research directed strategies for pest control.

Characterization of antennal chemosensilla and associated odorant binding as well as chemosensory proteins in the Eupeodes corollae (Diptera: Syrphidae).

Aphidophagous syrphids are important for pest control and pollination in various agroecosystems. However, the mechanism underlying olfaction, which is critical for insect' behavioral processes and fitness, has not been well understood in the family Syrphidae. Hence, we performed a systematic identification and characterisation of the antennal sensilla and two groups of soluble proteins, odorant-binding proteins (OBPs) and chemosensory proteins (CSPs), in the hoverfly Eupeodes corollae. (i) With scanning electron microscopy, four major types of sensilla (chaetic sensilla [two subtypes], trichoid sensilla, basiconic sensilla [two subtypes] and coeloconic sensilla), with numerous microtrichia, were first observed along the entire surface of aristate antennae of both sexes of E. corollae. Of these, only chaetic sensillum was found on the first two antennal segments, scape and pedicel, while the other types of sensilla were located on the flagellum. No marked difference was observed in the morphological structure or distributional pattern of any of the sensilla between the two sexes. (ii) By molecular cloning and bioinformatic analysis, 7 EcorCSPs and 28 EcorOBPs (20 classic OBPs, 5 minus-C OBPs, and 3 plus-C OBPs) were directly identified from the species, which all share the characteristic hallmarks of their family, including the presence of a signal peptide and conserved cysteine signature. (iii) RT-qPCR of these chemosensory genes showed predominately tissue-biased expression patterns; 32 of the 35 EcorOBPs/CSPs were uniquely or primarily expressed in the main olfactory organs, either the antennae or head. (iv) Among these, several genes (EcorCSP2 and EcorOBP1, 9, 12, 15-17, 20) appeared to be antenna-biased. In situ hybridization assays indicated that each antenna-biased chemosensory gene was expressed in a different number of cells, suggesting they might play a more vital role in odour recognition and perception and could be potential candidates to study their biological functions in vivo and in vitro. Together, our current findings provide a basis for future studies on how syrphids utilize chemical cues to regulate their behavior during interactions among the natural enemy, its prey, and host plant in agro-ecosystems.

Distribution and ultrastructure of the antennal sensilla of the grape weevil Naupactus xanthographus (Coleoptera: Curculionidae).

The grape weevil, Naupactus xanthographus Germar (Coleoptera: Curculionidae), is a polyphagous insect native to southern South America that causes considerable damage in grape and other fruit species. In this study, the morphology and ultrastructure of the antennae and the antennal sensilla of N. xanthographus were investigated using scanning electron microscopy and transmission electron microscopy. The antennae consist of a scape, a pedicel, a funicle, and a zone called the "club," which are all formed by a total of 12 antennomers. Different types of sensilla were observed: sensilla trichoidea, sensilla chaetica type 1 and 2, sensilla basiconica, and sensilla rod-like. No sexual dimorphism was observed. The possible functions of the sensilla are discussed in relation to their morphology and ultrastructure.

Typology and distribution of antennal sensory organs of adults Haematobia irritans of the Midwest Region of Brazil / Tipologia e distribuição de órgãos sensilares de Haematobia irritans adultas do Centro-Oeste do Brasil

Considering the great economic and sanitarian importance of Haematobia irritans − the development of resistance of this species to the main chemical insecticides used in its control, in several other localities of the world; as well as that different strains of the same species frequently present different types and distribution patterns −, the present aim study was to investigate the typology and distribution of different types of sensillae of H. irritans adults, from populations of this fly present in Brazilian Midwest, with emphasis on olfactory sensillae. This study provides new data on the typology and sensillary distribution of antennal sensilla of this fly. In the antennal segments were found non-innervated spinules and ten subtypes of sensilla: long bristles sensillum, long basiconic sensillum, blunt coeloconic sensillum, clavate coeloconic sensilla − single-tip and double-tip subtypes −, grooved coeloconic sensillum, long grooved coeloconic sensillum, trichoid sensillum, coeloconic sensillum, and smaller basiconic sensillum. A slight sexual dimorphism was observed in the antennal sensillae of H. irritans. These results provide a morphological basis for future investigations on olfactory-mediated behavior of this species, and could assist future studies for the development of alternative measures to the monitoring and control of this fly populations, with less environmental impact.(AU)

Considerando a grande importância econômica e sanitária de Haematobia irritans, o desenvolvimento de resistência desta espécie aos principais inseticidas químicos utilizados em seu controle, em diversas outras localidades do mundo, bem como que diferentes cepas de uma mesma espécie frequentemente apresentam diferentes tipos e padrões de distribuição sensilares, objetivou-se no presente trabalho investigar a tipologia e a distribuição dos diferentes tipos e subtipos sensilares de adulttos de H. irritans, oriunda de populações desta mosca presentes no centro-oeste brasileiro, com ênfase nas sensilas olfatórias. Este estudo apresenta novos dados sobre a tipologia e distribuição sensilar da antenna desta mosca. Em seus segmentos antenais foram observados pilosidades não enervadas e dez subtipos de sensilas, sendo: long bristles sensillum, long basiconic sensillum, blunt coeloconic sensillum, clavate coeloconic sensilla - single-tip and double-tip subtypes -, grooved coeloconic sensillum, long grooved coeloconic sensillum, trichoid sensillum, coeloconic sensillum, e smaller basiconic sensillum. Leve dimorfismo sexual foi observado em relação às sensilas antenais de H. irritans. Estes resultados fornecem uma base morfológica para futuras investigações sobre o comportamento mediado pelo olfato desta espécie, e poderão fomentar futuros estudos para desenvolvimento de medidas alternativas de monitoramento e controle de populações dessa mosca, com menor impacto.(AU)

Antennular Morphology and Contribution of Aesthetascs in the Detection of Food-related Compounds in the Shrimp Palaemon adspersus Rathke, 1837 (Decapoda: Palaemonidae).

Shrimp are an essential ecological component of marine ecosystems, and have commercial importance for human consumption and aquaculture. Like other decapod crustaceans, shrimp rely on chemical senses to detect and localize food resources by means of chemosensilla that are located mainly on the cephalothoracic appendages. Using the shrimp Palaemon adspersus, a model organism with omnivorous feeding behavior, we aimed to provide comparative information on the role of aesthetascs, antennular sensilla, and flicking behavior in food detection. To this end, we examined i) the morphology of antennular sensilla by field emission scanning electron microscopy, ii) the shrimp's sensitivity to a number of food-related compounds (amino acids and sugars) by means of whole-animal bioassays, and iii) the contribution of the aesthetasc sensilla to food detection. Our results showed that, aside from the aesthetascs, only three other main morphotypes of setae with chemoreceptive features were present in the antennules, thus accounting for relatively simple sensillar equipment. Nevertheless, we found broad-spectrum sensitivity of the shrimp to a number of amino acids (i.e., isoleucine, leucine, methionine, phenylalanine, glycine, tryptophan, cysteine, and tyrosine) and carbohydrates (trehalose, maltose, cellobiose, and fructose) that was consistent with the omnivorous or scavenging habits of the animal. Although aesthetasc ablation attenuated flicking behavior in a chemical stimulus-independent manner, success in detection and short-range localization of food did not rely on the presence of aesthetasc sensilla. This finding confirms the existence of a non-aesthetasc alternative pathway for feeding, with functional redundancy in simple generalist feeder models such as shrimp.

Development of antennal sensilla of Tetragonisca angustula Latreille, 1811 (Hymenoptera: Meliponini) during pupation / Desenvolvimento das sensilas antenais de Tetragonisca angustula latreille, 1811 (Hymenoptera: Meliponini) durante a pupação

Abstract The antennal sensilla are sensory organs formed by a group of neurons and accessory cells, which allow perception of environmental cues, which play a role as mechanoreceptors and chemoreceptors. This study describes the post-embryonic development of the antennal sensilla of the stingless Tetragonisca angustula (Hymenoptera: Meliponini) workers. The development of the antennal sensilla begins in the transition stage of the pre-pupae to white-eyed pupae. The sensilla are completely developed at the black-eyed pupae stage, but they are covered by the old cuticle. The sensilla are exposed to the environment only in newly emerged workers of T. angustula, but it is possible that environmental stimuli can be recognized due to the pores in the old cuticle.

Resumo As sensilas antenais são órgãos sensoriais formados por um conjunto de neurônios que captam estímulos ambientais e células acessórias, desempenhando as funções de mecanorreceptores e quimiorrecepterores. Este trabalho descreve o desenvolvimento pós-embrionário das sensilas antenais de operárias das abelhas sem ferrão Tetragonisca angustula (Hymenoptera: Meliponini). O desenvolvimento das sensilas tem início na transição de pré-pupa para pupa de olho branco e estão completamente desenvolvidas no estágio de pupa de olho preto, mas ainda estão cobertas pela cutícula velha. As sensilas estão completamente expostas em operárias recém-emergidas de T. angustula, mas é possível que estímulos ambientais sejam percebidos em estágios anteriores devido aos poros presentes na cutícula velha.

Fine structure of antennal sensilla of the spittlebug Philaenus spumarius L. (Insecta: Hemiptera: Aphrophoridae). I. Chemoreceptors and thermo-/hygroreceptors.

The meadow spittlebug, Philaenus spumarius (L.) (Hemiptera: Cercopoidea: Aphrophoridae), is a polyphagous species that transmits Xylella fastidiosa, a bacterium associated with "Olive Quick Decline Syndrome" in Southern Italy. In this study, the morphology and the ultrastructure of the antennal sensilla of P. spumarius were investigated. The antennae consist of three segments: a basal scape, a pedicel and a flagellum composed of a basal enlargement (ampulla) and a long segment (filament). The pedicel bears a single campaniform sensillum while the ampulla houses twelve coeloconic sensilla and three large basiconic sensilla. These latter sensilla show a smooth multiporous external cuticular wall and a total number of 27 sensory neurons per sensillum. The coeloconic sensilla belong to two morphologically distinct types: double-walled and single-walled sensilla. The sensory peg of the double-walled sensilla is smooth at the base and distally has a grooved cuticular surface with pores organized in spoke channels between each ridge. Three sensory neurons enter the lumen while at the basal level, before entering the peg, a fourth sensory neuron is found. The single-walled sensilla show an aporous thick cuticular wall and two sensory neurons entering the sensillar lumen, with a third neuron ending at the sensillum base.

Atypical mechanoreceptors in larvae of biting midges Forcipomyia nigra (Diptera: Ceratopogonidae).

The dorsolateral setae of Forcipomyia nigra have been investigated. They are mechanoreceptors, sensilla trichoidea, innerved by a single neuron. The tubular body is located at the base of the hair shaft. Although the fine structure of the dorsolateral setae is similar to dorsal setae that perform a double function: secretion of a hygroscopic viscous substance through the pores and mechanoreception dorsolateral setae, they do not secrete any fluid. In both types of setae, trichogen cells (hair forming cells) produce the hair shafts and thereafter do not retract from the cavity of the setae. They contain a large polyploid nucleus and expanded bundles of microtubules. In dorsolateral mechanoreceptors, the microtubules form a network around the nucleus of the trichogen cell and are especially numerous in the cytoplasm invading the interior of the seta, which is evidenced by immunofluorescence light microscopy. No tormogen cell, responsible for the production of the setal socket, was found. Our observations indicate that the dorsolateral setae are solely mechanoreceptors but their trichogen cells reveal some glandular activity.

Structure and Sensilla of the Mouthparts of the Spotted Lanternfly Lycorma delicatula (Hemiptera: Fulgoromorpha: Fulgoridae), a Polyphagous Invasive Planthopper.

Mouthparts are among the most important sensory and feeding structures in insects and comparative morphological study may help explain differences in feeding behavior and diet breadth among species. The spotted lanternfly Lycorma delicatula (White) (Hemiptera: Fulgoromorpha: Fulgoridae) is a polyphagous agricultural pest originating in China, recently established and becoming widespread in Korea, and more recently introduced into eastern North America. It causes severe economic damage by sucking phloem sap and the sugary excrement produced by nymphs and adults serves as a medium for sooty mold. To facilitate future study of feeding mechanisms in this insect, the fine-structural morphology of mouthparts focusing on the distribution of sensilla located on the labium in adult L. delicatula was observed using a scanning electron microscope. The mouthparts consist of a small cone-shaped labrum, a tubular labium and a stylet fascicle consisting of two inner interlocked maxillary stylets partially surrounded by two shorter mandibular stylets similar to those found in other hemipteran insects. The five-segmented labium is unusual (most other Fulgoromorpha have four segments) and is provided with several types of sensilla and cuticular processes situated on the apex of its distal labial segment. In general, nine types of sensilla were found on the mouthparts. Six types of sensilla and four types of cuticular processes are present on sensory fields of the labial apex. The proposed taxonomic and functional significance of the sensilla are discussed. Morphological similarities in the interlocking mechanism of the stylets suggest a relationship between Fulgoromorpha and Heteroptera.

Control of moth flight posture is mediated by wing mechanosensory feedback.

Flying insects rapidly stabilize after perturbations using both visual and mechanosensory inputs for active control. Insect halteres are mechanosensory organs that encode inertial forces to aid rapid course correction during flight but serve no aerodynamic role and are specific to two orders of insects (Diptera and Strepsiptera). Aside from the literature on halteres and recent work on the antennae of the hawkmoth Manduca sexta, it is unclear how other flying insects use mechanosensory information to control body dynamics. The mechanosensory structures found on the halteres, campaniform sensilla, are also present on wings, suggesting that the wings can encode information about flight dynamics. We show that the neurons innervating these sensilla on the forewings of M. sexta exhibit spike-timing precision comparable to that seen in previous reports of campaniform sensilla, including haltere neurons. In addition, by attaching magnets to the wings of moths and subjecting these animals to a simulated pitch stimulus via a rotating magnetic field during tethered flight, we elicited the same vertical abdominal flexion reflex these animals exhibit in response to visual or inertial pitch stimuli. Our results indicate that, in addition to their role as actuators during locomotion, insect wings serve as sensors that initiate reflexes that control body dynamics.

Differential effects of ambient temperature on warm cell responses to infrared radiation in the bloodsucking bug Rhodnius prolixus.

Thermoreceptors provide animals with background information about the thermal environment, which is at least indirectly a prerequisite for thermoregulation and assists bloodsucking insects in the search for their host. Recordings from peg-in-pit sensilla and tapered hairs on the antennae of the bug Rhodnius prolixus revealed two physiologically different types of warm cells. Both types responded more strongly to temperature pulses produced by switching between two air streams at different constant temperatures than to infrared radiation pulses employed in still air. In addition, both warm cells were better able to discriminate small changes in air temperature than in infrared radiation. As convective and radiant heat determines the discharge, it is impossible for a single warm cell to signal the nature of the stimulus unequivocally. Individual responses are ambiguous, not with regard to temperature change, but with regard to its source. We argue that the bugs use mechanical flow information to differentiate between pulses of convective and radiant heat. However, if pulses of radiant heat occur together with a constant temperature air stream, the mechanical cues would not allow avoiding ambiguity that convective heat introduces into radiant heat stimulation. In this situation, the warm cell in the tapered hairs produced stronger responses than those in the peg-in-pit sensilla. The reversal in the excitability of the two types of warm cells provides a criterion by which to distinguish the combination of convective and radiant heat from the stimuli presented alone.

Ultrastructure of antennal sensilla of a parasitoid fly, Pales pavida Meigen (Diptera: Tachinidae).

Pales pavida Meigen is obligated polyparasitic fly and important natural enemy of some most damaging forest or agricultural pests, and thus could contribute to the biological control of them. The external morphology of main olfactory organs in this tachinid was examined using stereopic microscopy and scanning electron microscopy, and types, distribution and density of sensilla were provided. The first two antennal segments, antennal scape and pedicel, are covered by microtrichiae and several mechanoreceptors. A pedicellar button is detected on antennal pedicel as well, after its separation with antennal funiculus. On antennal funiculus, five types of sensillar structures are observed including trichoid, basiconic, coeloconic, clavate sensilla and sensory pit with subtype II basiconic sensilla and a type of rarely described coeloconic-like sensilla in it, respectively. There are two specific sensillar characteristics of Pales pavida, two types of sensory pit on antennal funiculus and lower densities of all sensilla types than relatively monoparasitic species, which may serve as applicable evidence on their adaption to environment and lifestyle. Besides, the morphology of pedicellar button in tachinids is first addressed, armed with a discussion of their possible function.

Morphological and morphometric studies of the antennal sensilla from two populations of Atta robusta (Borgmeier 1939) (Hymenoptera: Formicidae) / Estudo morfológico e morfométrico das sensilas antenais de Atta robusta (Borgmeier 1939) (Hymenoptera: Formicidae)

The ant Atta robusta is endemic to the “restinga” ecosystems where it has an important role in the dynamics of seed dispersal. Despite its importance, A. robusta is considered a threatened species. In this study we analyzed the antennal sensory organs of two different populations of A. robusta (from the cities of São Mateus and Maricá in in Espírito Santo and Rio de Janeiro States, respectively) using a scanning electron microscope (SEM). SEM revealed different types of sensilla in the A. robusta antennae, i.e., curved and straight trichoid, basiconic, ampullacea and coeloconic, which were highly abundant found in the distal flagellomeres (F) compared with other antenna regions. There were differences in samples collected from two locations in terms of the sensilla number and length. The average numbers of straight and curved trichoid sensillae numbers were different in F9 and F8, respectively, while the average length of the curved trichoid sensilla was only different in F9. These variations in sensory organs between two populations of A. robusta may indicate an adaptation of this species to different environmental conditions. The number of straight trichoid sensilla was only significantly different in F9.

Atta robusta é uma espécie de formiga endêmica, com papel importante na dinâmica dos ecossistemas de restinga. Apesar de sua importância como dispersora de sementes nesse tipo de ecossistema, essa espécie encontra-se ameçada de extinção. O presente trabalho lançou mão da microscopia eletrônica de varredura (MEV) para descrever as sensilas antenais de A. robusta e investigar diferenças entre sensilas antenais dessa espécie em indivíduos coletados em localidades diferentes, nos municípios de São Mateus (Estado do Espírito Santo) e Maricá (Estado do Rio de Janeiro). Diferentes tipos de sensilas como tricoideas retas e curvadas, basicônicas, ampuláceas e celocônicas foram encontradas nas antenas, sendo que todas são mais numerosas no flagelomero nove (F9) ou mais distal. Houve diferença em número e em comprimento das sensilas tricoideas retas e curvatas em F8 e F9 entre os indivíduos das duas localidades. Os números médios das sensilas tricoides retas e curvadas foram diferentes para os F9 e F8, respectivamente, enquanto que o comprimento médio das sensilas tricoides curvadas foi diferente para o F9. Essa variação na quantidade de sensilas antenais entre as populações é, possivelmente, uma plasticidade fenotípica, característica importante para a adaptação de espécies a variações ambientais. Esse trabalho representa um estudo preliminar na tentativa de se estudar a variação nos órgãos sensoriais entre diferentes populações de A. robusta.

Study on cheliceral sensilla of the brown dog tick Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) involved in taste perception of phagostimulants.

Phagostimulants are chemical compounds that stimulate feeding. Some tick species are known to have pores in their inner cheliceral digits, called pit sensillum (ps), which are involved in taste perception. This study investigated the existence of ps in chelicerae of Rhipicephalus sanguineus ticks by scanning electron microscopy (SEM) and their involvement in the perception of phagostimulatory substances, such as the salts potassium chloride and sodium chloride (KCl and NaCl), sugars (glucose, sucrose and fructose), purines (guanine and hypoxanthine), the nucleotide adenosine triphosphate (ATP) and the tripeptide reduced glutathione (GSH), as well as their combinations at different concentrations. By means of scanning electron microscopy, a ps was observed at the expected location. Using a single-sensillum recording technique, strong activity by R. sanguineus cheliceral sensilla in response to glucose, ATP, GSH and high concentrations of salts was recorded. The responses to ATP and to KCl at 1M were multicellular, while the responses to the other stimulant compounds were monocellular. Glucose and GSH stimulated different neurons. The taste response of R. sanguineus chelicerae seemed to be selective, given that substances that were not expected to participate in this tick's biology were not perceived.

Ultrastructure of sensory equipments on the heads of Kallitaxila granulata (Stål) (Hemiptera: Fulgoromorpha: Tropiduchidae).

The polyphagous planthopper, Kallitaxila granulata (Stål) (Hemiptera: Fulgoromorpha: Tropiduchidae), has been recently introduced into southeastern China, the Philippine islands, and Hawaii, where it has done significant damage to agricultural and forest ecosystems. The external morphology of the heads of adult male and female K. granulata was examined using scanning electron microscopy. Seven types of sensilla were reported: trichoid sensilla and campaniform sensilla on the antennal pedicel, antennal scape and maxilla; plate organs on the antennal pedicel; coeloconic sensilla in Bourgoin's organ on the expanded flagellar base; ampullaceal sensilla on the antennal pedicel; wavy-pit sensilla on the antennal pedicel and antennal scape; and coin-shaped sensilla on each lateral side of the labium. Evans' organ was described as placoid sensilla sunk into shallow cuticular cavities below the antennae. The external morphology, distribution, and abundance of sensilla located on antennae, maxillae, and labium in K. granulata were illustrated, with a brief discussion of their taxonomic, phylogenetic, and putative functional significance.

Morphology and histology of secretory setae in terrestrial larvae of biting midges of the genus Forcipomyia (Diptera: Ceratopogonidae).

Apneustic larvae of the genus Forcipomyia possess unique secretory setae located on the dorsal surface along the body in two rows, one pair on each thoracic and abdominal segment and two pairs on the head. Morphological and histological studies of secretory setae in fourth instar larvae of Forcipomyia nigra (Winnertz) and Forcipomyia nigrans Remm indicate they are modified mechanoreceptors (sensilla trichodea) in which the trichogen cell is a glandular cell producing a hygroscopic secretion. The cytoplasm of the glandular trichogen cell fills the lumen of a secretory seta, which shows one or more pores on the apex. The cytoplasm contains numerous microtubules responsible for transportation of proteinaceous vesicles, and an extremely large polyploid nucleus typical of gland cells. The main role of the hygroscopic secretion is to moist the body and thus facilitate cuticular respiration.

Ultrastructural characterization of olfactory sensilla and immunolocalization of odorant binding and chemosensory proteins from an ectoparasitoid Scleroderma guani (Hymenoptera: Bethylidae).

The three-dimensional structures of two odorant binding proteins (OBPs) and one chemosensory protein (CSP) from a polyphagous ectoparasitoid Scleroderma guani (Hymenoptera: Bethylidae) were resolved bioinformatically. The results show that both SguaOBP1 and OBP2 are classic OBPs, whereas SguaCSP1 belongs to non-classic CSPs which are considered as the "Plus-C" CSP in this report. The structural differences between the two OBPs and between OBP and CSP are thoroughly described, and the structural and functional significance of the divergent C-terminal regions (e.g., the prolonged C-terminal region in SguaOBP2 and the additional pair of cysteines in SguaCSP1) are discussed. The immunoblot analyses with antisera raised against recombinant SguaOBP1, OBP2, and CSP1, respectively, indicate that two SguaOBPs are specific to antennae, whereas SguaCSP1, which are more abundant than OBPs and detected in both male and female wasps, expresses ubiquitously across different tissues.We also describe the ultrastructure of the antennal sensilla types in S. guani and compare them to 19 species of parasitic Hymenoptera. There are 11 types of sensilla in the flagellum and pedicel segments of antennae in both male and female wasps. Seven of them, including sensilla placodea (SP), long sensilla basiconica (LSB), sensilla coeloconica (SC), two types of double-walled wall pore sensilla (DWPS-I and DWPS-II), and two types of sensilla trichodea (ST-I and ST-II), are multiporous chemosensilla. The ultralsturctures of these sensilla are morphologically characterized. In comparison to monophagous specialists, the highly polyphagous generalist ectoparasitoids such as S. guani possess more diverse sensilla types which are likely related to their broad host ranges and complex life styles. Our immunocytochemistry study demonstrated that each of the seven sensilla immunoreacts with at least one antiserum against SguaOBP1, OBP2, and CSP1, respectively. Anti-OBP2 is specifically labeled in DWPS-II, whereas the anti-OBP1 shows a broad spectrum of immunoactivity toward four different sensilla (LSB, SP, ST-I and ST-II). On the other hand, anti-CSP1 is immunoactive toward SP, DWPS-I and SC. Interestingly, a cross co-localization pattern between SguaOBP1 and CSP1 is documented for the first time. Given that the numbers of OBPs and CSPs in many insect species greatly outnumber their antennal sensilla types, it is germane to suggest such phenomenon could be the rule rather than the exception.