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Schematic diagram of an olfactory sensillum trichodeum with one receptor cell and three auxiliary cells. The cuticular hair is 5 Jlm thick and 300 Jlm long (by courtesy of T. A.
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Context 1
... Olfactory Sensill um Insect olfactory cells are characteristically grouped and closely associated with non-neuronal accessory or auxiliary cells. A group of four to six, seldom up to 20, cells together with the associated cuticular apparatus is called a sensillum ( Figure 1). All of these cells may contribute to the electrical signals recorded from the sensillum. Each receptor cell of an olfactory sensillum is usually tuned to a different key compound, often to a pheromone component (Kaissling 1979, Priesner 1979b, 1985a. Typically three auxiliary cells envelope the soma region of the receptor neurons: the innermost is the thecogen cell, enclosed by the trichogen and the tormogen cell (Keil & Steinbrecht 1984). The latter two cells have a strongly folded apical membrane and may control the composition of the extracellular fluid within the hair (Thurm 1974, Phillips & Vande Berg 1976a,b, Wieczorek 1982, the sensillum lymph, also called sensillum liquor (Ernst 1969) or receptor lymph. This fluid provides the ionic milieu for the dendrites of the receptor cells (Thurm & Kiippers 1980) and contains proteins that sequester the odor molecules within the hair (Vogt & Riddiford 1981a,b, Kaissling et al 1985. Size and shape of the cuticular parts of olfactory sensilla vary enormously and are used to categorize the sensilla (Slifer 1970, Altner & Prillinger 1980. The hair-like extensions of the sensilla trichodea in moths can reach 500 JIm length and are a few micrometers thick (Sanes & Hildebrand 1976a, Keil ...
Context 2
... the resting state, a transepithelial potential of about + 30 m V can be recorded from the opened tip (Figure 1) of an olfactory hair of male Antheraea po[yphyemus with the reference electrode in the hemolymph space of the antenna (Kaissling & Thorson 1980). Odor stimulation causes a negative deflection of the transepithelial potential (Figures 2, 3). This change of potential is referred to here as a "receptor potential." The receptor potential can be as large as 20 or 30 m V; it rises within fractions of a second and falls more slowly, within seconds after the end of the stimulus. In these recordings the receptor potential is usually accompanied by nerve impulses, with an initial positive phase lasting 1-2 ms and a longer negative phase. The peak-to-peak amplitude of the extracellularly recorded nerve impulses can reach 10 mV (De Kramer et al 1984) and is often characteristic of a particular receptor cell type. For example, the "acetate" cell of Antheraea polyphemus discharges larger impulses than the "al dehyde" cell and also has larger receptor potentials (Kaissling 1979). The differences in the extracellularly recorded response amplitudes were correlated with the diameters of the outer dendritic segments of the cells ...
Context 3
... of electrical responses in olfactory receptors has been studied using equivalent circuit diagrams of the sensillum trichodeum of Antheraea polyphemus (Kaissling & Thorson 1980, de Kramer et al 1984, de Kramer 1985. As in earlier analyses (Thurm 1963, Rees 1968, Morita 1972), these diagrams have two main current paths from the hair tip toward the hemolymph space. One pathway leads from the sensillum lymph space across the folded apical membranes of the trichogen and tormogen cells into these accessory cells and continues through their basolateral mem branes into the hemolymph. The other pathway enters the receptor cell through the dendritic membrane and leaves the cell in the soma region. Most probably, this pathway crosses the thecogen cell before entering the hemolymph. Further possible current paths through the clefts between the cells have been neglected because the presence of septate junctions ( Figure 1) and the distribution of tracer compounds (Keil & Steinbrecht 1983;T. A. Keil, unpublished) suggested high extracellular resistance. The functional analyses were based on morphological measurements (Keil 1984a, 1984c, Steinbrecht & Gnatzy 1984, Gnatzy et aI 1984, the ionic composition of the sensillum lymph, and the electrical responses to chemical and electrical ...
Context 4
... complete model of the sensillum circuit should include the sources of membrane potentials in the sensillum. The transepithelial potential may originate in an electrogenic potassium pump located in the folded apical membranes of the trichogen and tormogen cells. Evidence for this idea, first presented for mechanoreceptive sensilla (Thurm 1972(Thurm , 1974, was the immediate drop of the potential after oxygen deprivation and the presence of membrane-associated particles (portasomes, Harvey 1980) in the folded membrane. The electrogenic pump may be partially responsible for the nonlinear voltage-current relationship measured across the sensillum (Kaissling & Thorson 1980). The transepithelial potential may serve to enhance the dendritic membrane potential and hence also the receptor potential. Experiments in zygaenid moths, however, showed no direct correlation of transepithelial and receptor potential after poisoning with HCN and during the recovery period (Levinson et aI ...
Citations
... In other nymphalid, B. anynana, SBa have been characterized as multiporous, with the presence of 100 dendritic branches (Yuvaraj et al. 2018). In addition, SBa is associated with the detection of stimuli of chemical nature (Kaissling 1986;Isidoro et al. 1998), in recognition of plant volatiles and other semiochemicals (Kaissling 1971;Sun et al. 2011;Binyameen et al. 2012;Ghaninia et al. 2014). ...
In the present study, we investigated the antennal morphology and the distribution and typology of sensilla in antennae of male and female Caligo illioneus illioneus Cramer (Lepidoptera: Nymphalidae), examined by scanning electron microscopy—SEM. The insect was identified by morphological and molecular means, and the COI gene of this subspecies was sequenced and deposited in GenBank. The SEM results showed that antennae of both sexes do not present dimorphism, as they cannot be distinguished from each other in terms of morphology. In addition, the ventral region of the flagellum has longitudinal carinae. In both sexes, seven types of sensilla were identified along the scape, pedicel and flagellum: Böhm’s bristles and sensilla auricillica, basiconica, chaetica, coeloconica, squamiformia, and trichodea. Subtypes I and II were characterized for Böhm's bristles and sensilla basiconica and chaetica according to the length, because morphometric result was statistically different among individuals of the same sex. In addition, the flagellum contains the vast majority of sensilla and their subtypes, except for Böhm’s bristles, present only in the basal region. This study provides valuable information about the antennal morphology and sensilla typology in C. i. illioneus, contributing with morphological evidence on the sensory system of butterflies, mainly in the genus Caligo, which is helpful to assist behavioral and electrophysiological studies.
... The binding of receptor proteins on sensory cells to chemicals in the air or solution initiates a sequence of biochemical reactions, resulting in the production of electrical signals, which are then transmitted to the nervous system. The brain interprets these electrical signals as a specific scent or flavor after they are processed by the nervous system [143]. ...
Hair, or hair-like fibrillar structures, are ubiquitous in biology, from fur on the bodies of mammals, over trichomes of plants, to the mastigonemes on the flagella of single-celled organisms. While these long and slender protuberances are passive, they are multifunctional and help to mediate interactions with the environment. They provide thermal insulation, sensory information, reversible adhesion, and surface modulation (e.g., superhydrophobicity). This review will present various functions that biological hairs have been discovered to carry out, with the hairs spanning across six orders of magnitude in size, from the millimeter-thick fur of mammals down to the nanometer-thick fibrillar ultrastructures on bateriophages. The hairs are categorized according to their functions, including protection (e.g., thermal regulation and defense), locomotion, feeding, and sensing. By understanding the versatile functions of biological hairs, bio-inspired solutions may be developed across length scales.
... In theory, this variation may affect the mating behaviors between P. xylostella from different geographical regions. For instance, while sex pheromone components can have a strong trapping or straying effect on a population of P. xylostella in one Trichoid sensilla are sensitive to species-specific pheromones in insects (Kaissling, 1986;Steinbrecht, 1997). Our previous study revealed that there were 17 types of sensilla on the antennae of P. xylostella: trichodea (2 subtypes), basiconica, coeloconica (3 subtypes), Böhm's bristles (2 subtypes), styloconica (2 subtypes), squamiformia, auricillica, furcatea (3 subtypes), cupuliform organs, and terminal sensory pegs (Yan et al., 2017). ...
Sex pheromones, which consist of multiple components in specific ratios promote intraspecific sexual communications of insects. Plutella xylostella (L.) is a worldwide pest of cruciferous vegetables, the mating behavior of which is highly dependent on its olfactory system. Long trichoid sensilla on male antennae are the main olfactory sensilla that can sense sex pheromones. However, the underlying mechanisms remain unclear. In this study, 3 sex pheromone components from sex pheromone gland secretions of P. xylostella female adults were identified as Z11‐16:Ald, Z11‐16:Ac, and Z11‐16:OH in a ratio of 9.4 : 100 : 17 using gas chromatography – mass spectrometry and gas chromatography with electroantennographic detection. Electrophysiological responses of 581 and 385 long trichoid sensilla of male adults and female adults, respectively, to the 3 components were measured by single sensillum recording. Hierarchical clustering analysis showed that the long trichoid sensilla were of 6 different types. In the male antennae, 52.32%, 5.51%, and 1.89% of the sensilla responded to Z11‐16:Ald, Z11‐16:Ac, and Z11‐16:OH, which are named as A type, B type, and C type sensilla, respectively; 2.93% named as D type sensilla responded to both Z11‐16:Ald and Z11‐16:Ac, and 0.34% named as E type sensilla were sensitive to both Z11‐16:Ald and Z11‐16:OH. In the female antennae, only 7.53% of long trichoid sensilla responded to the sex pheromone components, A type sensilla were 3.64%, B type and C type sensilla were both 0.52%, D type sensilla were 1.30%, and 1.56% of the sensilla responded to all 3 components, which were named as F type sensilla. The responding long trichoid sensilla were located from the base to the terminal of the male antennae and from the base to the middle of the female antennae. The pheromone mixture (Z11‐16:Ald : Z11‐16:Ac : Z11‐16:OH = 9.4 : 100 : 17) had a weakly repellent effect on female adults of P. xylostella . Our results lay the foundation for further studies on sex pheromone communications in P. xylostella .
... Odor molecules bind to chemosensory proteins (CSPs) or odorant binding proteins (OBPs) (Leal 2013) to form complexes, and then are transported to sensory neuron membrane proteins (SNMPs) , ionotropic receptors (IRs) (Benton et al. 2009), or odorant receptors (ORs) (Trible et al. 2017). Subsequently, chemical signals are converted into electrical signals, which are transmitted to the central nervous system and regulate the behavioral responses of insects (Kaissling 1986). At the same time, in order to prevent odor molecules from repeatedly stimulating the olfactory system, odor degrading enzyme (ODE) (He et al. 2014) rapidly degrades odor molecules. ...
Chemosensory proteins (CSPs) are widely distributed in insect tissues and are involved in olfactory and non-olfactory functions. In this study, based on the transcriptome data of Agrilus zanthoxylumi Hou (Coleoptera: Buprestidae), the AzanCSP4 of was cloned by RT-PCR and bioinformatically analyzed, and RT-qPCR was conducted to analyze their expression levels of AzanCSP4 in different genders and tissues (head, thorax, abdomen, leg and wing). Sequence analysis showed that AzanCSP4 had an open reading frame (ORF) length of 366 bp, encoding 121 amino acids with an estimated molecular weight 13.96 kD. The encoded protein had no transmembrane domain, and the signal peptide was located in the position 1–15 at the N-terminal of the amino acid sequence. Sequence alignment revealed that AzanCSP4 had four conserved cysteines. Phylogenetic analysis revealed that the AzanCSP4 and AmalCSP6 from Agrilus mali Matsumura (Coleoptera: Buprestidae) were closely clustered into the same clade. RT-qPCR results showed that AzanCSP4 of A. zanthoxylumi was expressed in different tissues of both male and female adults, and the expression in the same tissue was greater in female adults than in male adults. The expression of AzanCSP4 in the head of female adults was significantly higher than that in other tissues of male and female adults. This study provides a theoretical basis for further research on the function of AzanCSP4, especially on the chemical communication mechanism in A. zanthoxylumi.
... Insects primarily rely on their antennal odor receptors to detect chemical signaling molecules, which are then converted into electrophysiological signals (Kaissling 1986). The electrophysiological techniques in insects enable the transformation of chemical signals into electrophysiological signals. ...
Cotesia ruficrus (Hymenoptera: Braconidae) is an endoparasitic natural enemy of various Lepidopteran pests, and it plays a significant role in integrated pest management. In the field survey of maize fields, we found for the first time that the indigenous parasitoid C. ruficrus parasitized the major invasive pest Spodoptera frugiperda (Lepidoptera: Noctuidae) in China. We identified 18 odorant-binding proteins (CrufOBPs) of C. ruficrus through the RNA-Seq method, and PCR analysis showed that 13 out of the CrufOBPs were highly expressed in antennae. Two CrufOBPs, CrufOBP3 with the highest antennal expression and CrufOBP17 with antenna-specific expression, were selected for protein biosynthesis in the prokaryotic protein expression system and subjected to protein purification. Through fluorescence binding assay, seven maize volatile compounds were selected for the antennal electroantennography (EAG) study, and the results indicated that female C. ruficrus exhibited distinct responses to these volatiles at different concentrations. Octanal and 2-heptanone of 10 mg mL⁻¹ were chosen for olfactory behavioral experiments because of their high EAG responses, and the results showed that C. ruficrus adults were significantly attracted at certain concentrations. Furthermore, in the cage experiments, 10 mg mL⁻¹ of 2-heptanone significantly increased the parasitism rate of C. ruficrus on S. frugiperda. These findings not only provide a theoretical basis for studying the odorant-binding protein family of C. ruficrus but also contribute to the development of novel pest control strategies for this invasive pest management.
... gracilicornis .And it was found that Sensilla basiconica is dominated by mechanoreceptive and olfactory functions. (Li Zhu et ali., 2010), Sensilla basiconica is selective for odors and can perceive plant volatile odors (Kaissling K, 1986). We speculate that it is mainly related to sensory odor, etc. ...
Abscract : Polyphylla gracilicornis , both adults and larvae can produce serious damage to crops. In this experiment, the antenna structure and sensors of P. gracilicornis were specifically observed using a stereoscopic microscope and a scanning electron microscope.We also analyzed the characteristics of tentacle structure and sensor types, morphology, number and distribution of male and female adults of P. gracilicornis .The results showed that both male and female antennae consisted of scape, pedicel and flagellum. The flagellum was divided into rod-like and gill-like parts, among which the flagellum like part of the male antennae consisted of seven segments, L1, L2, L3, L4, L5, L6 and L7, while the female antennae consisted of six segments. Observations of their male and female antennal sensors revealed that both sensor types were approximately the same, with a total of seven sensor types observed, namely Sensilla trichodea, Sensilla chaetica, Sensilla basiconica, Sensilla placodea, Sensilla coeloconica, Sensilla. But, the size and distribution of the male adult antennas differed from the female antennas. The basic study of the ultrastructure of antennas provided a basis for the study of the chemical communication mechanism of P. gracilicornis .
... Secondly, after the receptors convert chemical signals into electrophysiological signals and transmit them to the central nervous system of insects for integration, the brain issues instructions to guide insects to conduct physiological reactions. [3,4]. Insect receptors include three gene families: odorant receptors (ORs) that are sensitive to alcohols, ketones, and esters; ionotropic receptors (IRs) that sense amines and acids; and gustatory receptors (GRs) that sense soluble chemicals [5][6][7]. ...
Insects use a powerful and complex olfactory recognition system to sense odor molecules in the external environment to guide behavior. A large family of odorant receptors (ORs) mediates the detection of pheromone compounds. Anoplophora glabripennis is a destructive pest that harms broad-leaved tree species. Although olfactory sensation is an important factor affecting the information exchange of A. glabripennis, little is known about the key ORs involved. Here, we identified ninety-eight AglaORs in the Agla2.0 genome and found that the AglaOR gene family had expanded with structural and functional diversity. RT-qPCR was used to analyze the expression of AglaORs in sex tissues and in adults at different developmental stages. Twenty-three AglaORs with antennal-biased expression were identified. Among these, eleven were male-biased and two were female-biased and were more significantly expressed in the sexual maturation stage than in the post-mating stage, suggesting that these genes play a role in sexual communication. Relatively, two female-biased AglaORs were overexpressed in females seeking spawning grounds after mating, indicating that these genes might be involved in the recognition of host plant volatiles that may regulate the selection of spawning grounds. Our study provides a theoretical basis for further studies into the molecular mechanism of A. glabripennis olfaction.
... This difference between detection and tracking is best quantified in the context of the champion smellers in the insect worldmale moths. Males of many moth species can detect a single molecule of the female pheromone (Kaissling, 1986). However, this exquisite sensitivity does not allow them to track down females from a kilometer away as suggested by earlier studies (Bossert and Wilson, 1963;Collins and Potts, 1932). ...
... The sensitivity of individual ORNs and the convergence from ORNs to PNs allows insects to detect odors at low concentration with short latency. Estimates suggest that a single moth pheromone molecule can produce a change in firing rate in an ORN that is specific to pheromones (Kaissling, 1986). Even when ORNs are not specific to a single odor, they can still be sensitive to odors (Hallem and Carlson, 2006;Olsen et al., 2010). ...
Odors released from mates and resources such as a host and food are often the first sensory signals that an animal can detect. Changes in locomotion in response to odors are an important mechanism by which animals access resources important to their survival. Odor-modulated changes in locomotion in insects constitute a whole suite of flexible behaviors that allow insects to close in on these resources from long distances and perform local searches to locate and subsequently assess them. Here, we review changes in odor-mediated locomotion across many insect species. We emphasize that changes in locomotion induced by odors are diverse. In particular, the olfactory stimulus is sporadic at long distances and becomes more continuous at short distances. This distance-dependent change in temporal profile produces a corresponding change in an insect's locomotory strategy. We also discuss the neural circuits underlying odor modulation of locomotion.
... Studies of Noctuidae moth species have shown that sex pheromone molecules are detected by specialized odorant receptor neurons (ORNs) housed in the trichoid sensilla in male moth antennae (Kaissling, 1986). Pheromones released by female moths are taken up by pheromone-binding proteins (PBPs) and transported to pheromone receptors (PRs) (Leal, 2013;Fleischer & Krieger, 2018). ...
Moths possess an extremely sensitive and diverse sex pheromone processing system, in which pheromone receptors (PRs) are essential to ensure communication between mating partners. Functional properties of some PRs are conserved among species, which is important for reproduction. However, functional differentiation has occurred in some homologous PR genes, which may drive species divergence. Here, using genome analysis, seventeen PR genes were identified from Spodoptera frugiperda, S. exigua, and S. litura, which belong to six homologous groups (OR6, 11, 13, 16, 56, and 62); of which six PR genes (OR6, OR11, OR13, OR16, OR56, and OR62) were identified in S frugiperda and S. exigua, and five PR genes were identified in S. litura, excluding OR62. Using heterologous expression in Xenopus oocytes, we characterized the functions of PR orthologs including OR6, OR56, and OR62, which have not been clarified in previous studies. OR6 orthologs were specifically tuned to Z9,E12‐14:OAc, and OR62 orthologs were robustly tuned to Z7‐12:OAc in S. frugiperda and S. exigua. The optimal ligand for OR56 was Z7‐12:OAc in S. frugiperda, but responses were minimal in S. exigua and S. litura. In addition, SfruOR6 was male antennae‐specific, whereas SfruOR56 and SfruOR62 were male antennae‐biased. Our study further clarified the functional properties of PRs in three Spodoptera moth species, providing a comprehensive understanding of the mechanisms of intraspecific communication and interspecific isolation in Spodoptera. This article is protected by copyright. All rights reserved
... 7 Male responses to female sex pheromones are regulated by the olfactory circuitry. 8 Normally, pheromones are detected by olfactory receptor neurons (ORNs), which are housed in trichoid sensilla (TS) on male antennae, [9][10] while pheromone receptors (PRs), expressed on the dendrites of ORNs, underlie the specificity of these pheromones. 11 ORNs can be classified into different subclasses depending on their response profiles. ...
BACKGOUND
Sex pheromones of the fall armyworm, Spodoptera frugiperda, show differences in composition and proportions in different geographical populations, but always contain Z9‐14:OAc as the major component. Odorant receptor neurons (ORNs) housed in the long trichoid sensilla (TS) of male antennae are essential to detect female‐released sex pheromones in moths.
RESULTS
In this study, we identified seven components from pheromone gland extracts of female S. frugiperda in the Yunnan population from China, including (Z)‐7‐dodecen‐1‐yl acetate (Z7‐12:OAc), (Z)‐9‐tetradecenal (Z9‐14:Ald), (Z)‐9‐dodecen‐1‐yl acetate (Z9‐12:OAc), (Z)‐9‐tetradecen‐1‐yl acetate (Z9‐14:OAc), (E)‐11‐tetradecen‐1‐yl acetate (E11‐14:OAc), (Z)‐11‐tetradecen‐1‐yl acetate (Z11‐14:OAc) and (Z)‐11‐hexadecen‐1‐yl acetate (Z11‐16:OAc) at a ratio of 1.2:4:0.8:79.1:1.6:1.6:11.7 by gas chromatography coupled with mass spectrometry. Gas chromatography‐electroantennographic detection showed that Z9‐14:OAc, Z7‐12:OAc and Z11‐16:OAc are the male antennal active components. Peripheral coding of pheromones in males was investigated by single sensillum recording. Five functional neurons housed in three types of TS were identified based on profiles of neuronal responses, which are responsible for attractive component Z9‐14:OAc, synergistic components Z7‐12:OAc, Z11‐16:OAc, interspecific pheromones (Z)‐9‐tetradecen‐1‐ol (Z9‐14:OH) and (Z,E)‐9,12‐tetradecadien‐1‐yl acetate (Z9,E12‐14:OAc), respectively. Wind tunnel and field tests demonstrated that a ternary combination of Z9‐14:OAc, Z7‐12:OAc and Z11‐16:OAc at a ratio of 88:1:11 shows the strongest attractiveness to males.
Conclusion
An optimized pheromone blend of Z9‐14:OAc, Z7‐12:OAc and Z11‐16:OAc in an 88:1:11 ratio was identified for monitoring the invasive pest S. frugiperda in China. Five functional ORNs encoding intra‐ and interspecific pheromones were identified in male antennae, of which three neurons encode attractive component Z9‐14:OAc, synergistic components Z7‐12:OAc and Z11‐16:OAc, respectively, and the other two neurons encode interspecific pheromones Z9‐14:OH and Z9,E12‐14:OAc, separately. © 2022 Society of Chemical Industry.
