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The Coenobitidae (Decapoda, Anomura, Paguroidea) is a taxon of hermit crabs that includes two genera with a fully terrestrial life style as adults. Previous studies have shown that Coenobitidae have evolved a sense of spatial odor... more
The Coenobitidae (Decapoda, Anomura, Paguroidea) is a taxon of hermit crabs that includes two genera with a fully terrestrial life style as adults. Previous studies have shown that Coenobitidae have evolved a sense of spatial odor localization that is behaviorally highly relevant. Here, we examined the central olfactory pathway of these animals by analyzing central projections of the antennular nerve of Coenobita clypeatus, combining backfilling of the nerve with dextran-coupled dye, Golgi impregnations and three-dimensional reconstruction of the primary olfactory center, the antennular lobe. The principal pattern of putative olfactory sensory afferents in C. clypeatus is in many aspects similar to what have been established for aquatic decapod crustaceans, such as the spiny lobster Panulirus argus. However, there are also obvious differences that may, or may not represent adaptations related to a terrestrial lifestyle. In C. clypeatus, the antennular lobe dominates the deutocerebrum, having more than one thousand allantoid-shaped subunits. We observed two distinct patterns of sensory neuron innervation: putative olfactory afferents from the aesthetascs either supply the cap/subcap region of the subunits or they extend through its full depth. Our data also demonstrate that any one sensory axon can supply input to several subunits. Putative chemosensory (non-aesthetasc) and mechanosensory axons represent a different pathway and innervate the lateral and median antennular neuropils. Hence, we suggest that the chemosensory input in C. clypeatus might be represented via a dual pathway: aesthetascs target the antennular lobe, and bimodal sensilla target the lateral antennular neuropil and median antennular neuropil. The present data is compared to related findings in other decapod crustaceans.
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The Drosophila melanogaster subgroup has been the focus of numerous studies about evolution. We address the question of how the olfactory code has evolved among the nine sister species. By using in vivo electrophysiological measurements,... more
The Drosophila melanogaster subgroup has been the focus of numerous studies about evolution. We address the question of how the olfactory code has evolved among the nine sister species. By using in vivo electrophysiological measurements, so called single-cell recordings, we have established the ligand affinity of a defined subset of olfactory receptor neurons (ORNs) across all nine species. We show that the olfactory code as relayed by the investigated subset of ORNs is conserved to a striking degree. Distinct shifts in the code have occurred only within the simulans clade. However, these shifts are restricted to an altered tuning profile of the same single ORN type in all three of the simulans siblings and a more drastic change unique to D. sechellia, involving a complete loss of one sensillum type in favour of another. The alterations observed in D. sechellia may represent a novel host-specific adaptation to its sole host, morinda fruit (Morinda citrifolia). The overall high degree of similarity of the code within the subgroup is intriguing when considering the great variety in distributions as well as in habitat and host choice of the siblings, factors that could greatly affect the olfactory system.
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Within Crustacea, representatives of at least five major taxa have succeeded in the transition from an aquatic to a fully terrestrial lifestyle: Isopoda, Amphipoda, Astacida, Anomura, and Brachyura. Land-living crustaceans are fascinating... more
Within Crustacea, representatives of at least five major taxa have succeeded in the transition from an aquatic to a fully terrestrial lifestyle: Isopoda, Amphipoda, Astacida, Anomura, and Brachyura. Land-living crustaceans are fascinating animals that during a very limited time period at an evolutionary time scale have adapted to a number of diverse terrestrial habitats in which they have become highly
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The hawkmoth, Manduca sexta, has been a keystone system for developmental, neurobiological, and ecological studies for several decades. Because many of its behaviors are driven by olfactory cues, a thorough understanding of the Manduca... more
The hawkmoth, Manduca sexta, has been a keystone system for developmental, neurobiological, and ecological studies for several decades. Because many of its behaviors are driven by olfactory cues, a thorough understanding of the Manduca olfactory system is essential to studying its biology. With the aim of functionally characterizing single antennal olfactory sensory neurons (OSNs) and determining their detailed topographic location, we performed systematic single-sensillum recordings on 4 morphological types of olfactory sensilla: trichoid-A and -B and basiconic-A and -B. We were able to unambiguously differentiate the colocalized cells associated with single sensilla based on their spike amplitudes. Using a panel of 61 biologically relevant compounds established in behavioral and gas chromatography-electrophysiology experiments, we made 223 recordings from these sensilla. Based on the response spectra of 187 responding OSNs, the sensilla fell into 12 distinct functional classes enc...
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The sphinx moth Manduca sexta is a well-studied insect with regard to central olfactory functions. Until now, the innervation patterns of olfactory receptor neurons into the array of olfactory glomeruli in the antennal lobe have, however,... more
The sphinx moth Manduca sexta is a well-studied insect with regard to central olfactory functions. Until now, the innervation patterns of olfactory receptor neurons into the array of olfactory glomeruli in the antennal lobe have, however, been unclear. Using optical imaging to visualize calcium dynamics within the antennal lobe we demonstrate specific patterns elicited by sex pheromone components and plant-derived odours. These patterns mainly reflect receptor neuron activity. Within the male-specific macroglomerular complex the two major pheromone components evoke stereotyped activity in either of two macroglomerular complex glomeruli. Based on previous knowledge of output neuron specificity, our results suggest a matching of information between input and output in the macroglomerular complex. Plant odours evoked activity in the sexually isomorphic glomeruli. Two major results were obtained: (1). terpenes and aromatic compounds activate different clusters of glomeruli with only min...
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Olfactory receptor neurons on the antennae of the African fruit chafer species Pachnoda marginata (Coleoptera: Scarabaeidae) were examined through extensive use of gas chromatography linked with electrophysiological recordings from single... more
Olfactory receptor neurons on the antennae of the African fruit chafer species Pachnoda marginata (Coleoptera: Scarabaeidae) were examined through extensive use of gas chromatography linked with electrophysiological recordings from single olfactory receptor neurons. Contacted neurons were stimulated with a large number of extracted volatiles from 22 different fruits and with 64 synthetic plant compounds. Extracted fruit volatiles were identified using linked gas chromatography-mass spectrometry. In total, 48 different odor compounds were found to elicit responses. Analysis of the response spectra of the contacted neurons (n = 232) revealed the presence of 28 classes of receptor neurons. The neurons exhibited strong selectivity as well as high sensitivity. Eleven of the identified classes were selectively activated by single compounds, while the remaining were activated by 2-6 compounds. Several receptor neurons that were activated by more than one compound responded to compounds sha...
Research Interests: Pheromones, Comparative Physiology, Comparative, Biological Sciences, Odorant Receptor, and 14 moreAnimals, Smell, Plants, Fruit, Gas Chromatography, Neurons, Beetles, Odors, Gas Chromatography/mass Spectrometry, Sensitivity and Specificity, High Sensitivity, Structural Similarity Index, Response Spectra, and Volatilization
Inheritance patterns for sex pheromone production in females, pheromone detection on male antennal olfactory receptor cells, and male pheromone behavioral responses were studied in pheromonally distinct populations of European corn borers... more
Inheritance patterns for sex pheromone production in females, pheromone detection on male antennal olfactory receptor cells, and male pheromone behavioral responses were studied in pheromonally distinct populations of European corn borers from New York State. Gas chromatographic analyses of pheromone glands, single sensillum recordings, and flight tunnel behavioral analyses were carried out on progeny from reciprocal crosses, as well as on progeny from subsequent F(2) and maternal and paternal backcrosses. The data show that the production of the female pheromone blend primarily is controlled by a single autosomal factor, that pheromone-responding olfactory cells are controlled by another autosomal factor, and that behavioral response to pheromone is controlled by a sex-linked gene. F(1) males were found to possess olfactory receptor cells that give spike amplitudes to the two pheromone isomers that are intermediate to those of the high and low amplitude cells of the parent populations. Fifty-five percent of the F(1) males tested responded fully to pheromone sources ranging from the hybrid (E)-11-tetradecenyl acetate/(Z)-11-tetradecenyl acetate (E/Z) molar blend of 65:35 to the E/Z molar blend of 3:97 for the Z morph parents, but very few responded to the E/Z molar blend of 99:1 for the E morph parents. Data on the inheritance patterns support speculation that the Z morph is the ancestral and that the E morph is the derived European corn borer population.
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Pollination is often regarded as a mutualistic relationship between flowering plants and insects. In such a relationship, both partners gain a fitness benefit as a result of their interaction. The flower gets pollinated and the insect... more
Pollination is often regarded as a mutualistic relationship between flowering plants and insects. In such a relationship, both partners gain a fitness benefit as a result of their interaction. The flower gets pollinated and the insect typically gets a food-related reward. However, flower-insect communication is not always a mutualistic system, as some flowers emit deceitful signals. Insects are thus fooled by irresistible stimuli and pollination is accomplished. Such deception requires very fine tuning, as insects in their typically short life span, try to find mating/feeding breeding sites as efficiently as possible, and following deceitful signals thus is both costly and time-consuming. Deceptive flowers have thus evolved the ability to emit signals that trigger obligate innate or learned responses in the targeted insects. The behavior, and thus the signals, exploited are typically involved in reproduction, from attracting pheromones to brood/food-site cues. Chemical mimicry is one of the main modalities through which flowers trick their pollen vectors, as olfaction plays a pivotal role in insect-insect and insect-plant interactions. Here we focus on floral odors that specifically mimic an oviposition substrate, i.e., brood-site mimicry. The phenomenon is wide spread across unrelated plant lineages of Angiosperm, Splachnaceae and Phallaceae. Targeted insects are mainly beetles and flies, and flowers accordingly often emit, to the human nose, highly powerful and fetid smells that are conversely extremely attractive to the duped insects. Brood-site deceptive plants often display highly elaborate flowers and have evolved a trap-release mechanism. Chemical cues often act in unison with other sensory cues to refine the imitation.
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Research Interests: Network and Intracellular
Research Interests: Multidisciplinary, Movement, Female, Animals, Male, and 6 moreFeeding Behavior, PLoS one, Time Factors, Larva, Moths, and Aedes
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Birgus latro (L.) is the largest terrestrial hermit crab in the world. The species is widely distributed on remote Indo-Pacific islands of the tropics, but it is rapidly declining and is currently classified as data deficient on the IUCN... more
Birgus latro (L.) is the largest terrestrial hermit crab in the world. The species is widely distributed on remote Indo-Pacific islands of the tropics, but it is rapidly declining and is currently classified as data deficient on the IUCN red list. This review provides a synopsis of both published and unpublished data on the biology and ecology of B. latro.
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Outer dendritic segments of olfactory receptor neurons tuned to sex pheromone components were measured morphometrically on the antenna of male European corn borers. Ostrinia nubilalis, to determine if a correlation exists between the... more
Outer dendritic segments of olfactory receptor neurons tuned to sex pheromone components were measured morphometrically on the antenna of male European corn borers. Ostrinia nubilalis, to determine if a correlation exists between the diameter of the outer dendritic segment and the spike amplitude. The olfactory sensilla investigated each contained three receptor cells. Two cells were each specific for one of the two pheromone components, (Z)-11-tetradecenyl acetate (Z11-14:OAc) and (E)-11-tetradecenyl acetate (E11-14:OAc). Two strains of cornborers (Z and E) differ as to which of the two pheromone components is the main one. In both strains a large difference could be observed between the spike amplitudes elicited in the receptor cells by the two pheromone components, the main component always eliciting the large spike. In F1-hybrids (EZ) of these two strains, producing both pheromone components in similar quantities, the spike amplitudes were equal in the two pheromone-specific receptor cells. The third cell responded specifically to a behavioural antagonist. (Z)-9-tetradecenyl acetate (Z9-14:OAc) in both the parental and hybrid strains, and always showed the smallest spike amplitude. In a morphometric study, the outer dendritic segments were shown to differ more in diameter between the largest and second largest cell in the two parental strains than in the hybrid strain, while the smallest diameter cell did not differ between the different strains. These results imply that receptor cells with larger diameter produce spikes with greater amplitude. The data also show that all three types of receptor neurons display outer dendritic segments with strong variation in the diameter along the length of the segment, and with a pronounced taper towards the tip.
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W.-Q. WU, B. S. HANSSON and C. LOFSTEDT Department of Ecology, Lund University, Sweden ... Abstract. In addition to the pheromone components (2)-5-decenyl, (2)-7-dodecenyl and (Z)-9-tetradecenyl acetate (ZS-lO:OAc, Z7-12:OAc and... more
W.-Q. WU, B. S. HANSSON and C. LOFSTEDT Department of Ecology, Lund University, Sweden ... Abstract. In addition to the pheromone components (2)-5-decenyl, (2)-7-dodecenyl and (Z)-9-tetradecenyl acetate (ZS-lO:OAc, Z7-12:OAc and Z9-14:OAc), it has previously been ...
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Abstract. Receptor neurones with high selectivity and sensitivity to plant odours were found within short sensilla trichodea on the antenna of both female and male Spodoptera littoralis (Boisd.)(Lepidoptera: Noctuidae) by using... more
Abstract. Receptor neurones with high selectivity and sensitivity to plant odours were found within short sensilla trichodea on the antenna of both female and male Spodoptera littoralis (Boisd.)(Lepidoptera: Noctuidae) by using single-sensillum recording techniques. In 112 ...
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ABSTRACT Olfactory responses from the entire antenna and from single antennal sensilla of the male turnip moth, Agrotis segetum (Lepidoptea: Noctuidae Schiff.), were recorded after stimulation of the antenna with the sex pheromone... more
ABSTRACT Olfactory responses from the entire antenna and from single antennal sensilla of the male turnip moth, Agrotis segetum (Lepidoptea: Noctuidae Schiff.), were recorded after stimulation of the antenna with the sex pheromone component, (Z)-5-decenyl acetate (Z5-10:OAc), and three sulphur analogues of this compound. Adaptation of olfactory receptor neurones tuned to Z5-10:OAc was investigated after pre-exposure of these receptor neurones to the key stimulus and to the three sulphur analogues. Both electro-antennographic and single sensillum recordings revealed that the sulphur analogues had a significantly decreased effect compared to the natural stimulus. The pre-exposure experiments demonstrated that no further inhibition of neural activity was observed than could be expected from receptor neurone adaptation. Earlier reports, describing sulphur analogues as possible hyperagonists acting on moth pheromone receptor neurones, are not supported by the present study.
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ABSTRACT. Pheromone and plant volatile perception was studied with electroantennogram and single sensillum techniques in male and female turnip moths, Agrotis segetum Schiff. Lepidoptera, Noctuidae. The female is insensitive to the... more
ABSTRACT. Pheromone and plant volatile perception was studied with electroantennogram and single sensillum techniques in male and female turnip moths, Agrotis segetum Schiff. Lepidoptera, Noctuidae. The female is insensitive to the pheromone components and her ...
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The structures of different types of arthropod sensilla are compared and theories regarding the evolution of these sensory organs are presented. Arthropod sensilla are built according to a common plan, and are probably homologous to... more
The structures of different types of arthropod sensilla are compared and theories regarding the evolution of these sensory organs are presented. Arthropod sensilla are built according to a common plan, and are probably homologous to scolopidia. Certain similarities in the structure of sensilla in different arthropod groups can be the result of adaptations to specific environments. The structure of sensilla in insect groups, which are regarded to be ancestral, do not appear to be less sophisticated than in groups considered to be more advanced. The different types of pore systems, as well as the structural differentiations of insect olfactory sensillar types remain unexplained. Olfactory sensilla display a large degree of similarity among terrestrial arthropods, whereas crustacean sensilla diverge in structure. In holometabolous insects larval sensilla appear to be structurally quite advanced, and more complex than in the adult. During the ontogeny of both sensilla and scolopidia, these are differentiated in an epithelial layer, resulting in the formation of both sensory and enveloping cells. The developmental patterns of sensilla in the studied insect groups are similar. During the development of sensilla apoptotic process are usually active.
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In mosquitoes, precise and efficient finding of a host animal is crucial for survival. One of the poorly understood aspects of mosquito blood-feeding behavior is how these insects target an optimal site in order to penetrate the skin and... more
In mosquitoes, precise and efficient finding of a host animal is crucial for survival. One of the poorly understood aspects of mosquito blood-feeding behavior is how these insects target an optimal site in order to penetrate the skin and blood vessels without alerting the host animal. Here we provide new findings that a piercing structure of the mouthpart of the mosquitoes, the stylet, is an essential apparatus for the stage in blood feeding. Indeed, the stylet possesses a number of sensory hairs located at the tip of the stylet. These hairs house olfactory receptor neurons that express two conventional olfactory receptors of Aedes aegypti (AaOrs), AaOr8 and AaOr49, together with the odorant co-receptor (AaOrco). In vivo calcium imaging using transfected cell lines demonstrated that AaOr8 and AaOr49 were activated by volatile compounds present in blood. Inhibition of gene expression of these AaOrs delayed blood feeding behaviors of the mosquito. Taken together, we identified olfacto...
In a behavioral dual-choice test the orientational response of third-instar larvae of Spodoptera littoralis to a certain odor could be increased, following a former experience of the odor. The odorants used were either the odor of a... more
In a behavioral dual-choice test the orientational response of third-instar larvae of Spodoptera littoralis to a certain odor could be increased, following a former experience of the odor. The odorants used were either the odor of a previously eaten host plant or a synthetic plant odor presented in conjunction with food. Inexperienced third-instar larvae were either neutral or demonstrated a weak attraction to the odors, whereas experienced larvae were highly attracted. Furthermore it was demonstrated that the larvae did not generalize between the odor previously experienced and a novel odor.
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Olfactory studies have expanded beyond the study of single compound odor perception to explore the processing of complex mixtures and blends. The spatiotemporal presentation of blend stimuli is a challenging task requiring volatiles with... more
Olfactory studies have expanded beyond the study of single compound odor perception to explore the processing of complex mixtures and blends. The spatiotemporal presentation of blend stimuli is a challenging task requiring volatiles with diverse chemical and physical properties to be presented as a unified stimulus. This not only necessitates accurate control of the timing and homogeneity of the odor stream, but requires attention to the concentration of each blend component presented. We have developed a novel, multicomponent stimulus system for use in olfactory experiments that is capable of presenting up to 8 different odors simultaneously or in sequence at defined concentrations and time scales. Each odor is separated to minimize physical or chemical interactions, and stimulations are performed from a saturated headspace of the odor solution. Stimulus concentrations can be measured empirically or estimated using common gas laws. Photoionization detector measurements show that stimuli could be presented as cohesive blends or single components at frequencies of at least 10Hz without leakage or contamination. Solid phase microextraction measurements also show that the concentration of each component could be equilibrated through regulation of each component line's flow rate based on the different partial vapor pressures of the odorants. This device provides a unique method for introducing complex volatile mixtures for olfactory studies in a variety of animal taxa and allows for accurate control of odor intensities in both time and space.
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Pheromone detecting sensory neurons in moths are known to be highly sensitive and selective. Female-emitted sexual pheromones are normally mixtures of a few to several components. However, not much is known about how receptor neurons... more
Pheromone detecting sensory neurons in moths are known to be highly sensitive and selective. Female-emitted sexual pheromones are normally mixtures of a few to several components. However, not much is known about how receptor neurons respond to blends of compounds. In the present study we investigated how four physiological types of pheromone component-selective neurons responded to binary mixtures or to the complete blend in the turnip moth Agrotis segetum. We found that responses to mixtures only rarely differed from that to the excitatory component alone. The mixture interactions were exclusively suppressive and occurred only at high concentrations. Therefore we conclude that the, in A. segetum, commonly observed mixture interactions observed in higher brain centra are mainly the result of central nervous processing and that information about the pheromone components reaches the antennal lobes virtually unaltered. In addition, we found a physiological type of receptor neuron, responding selectively to one of the female-emitted pheromone components, that has previously not been observed in the Swedish population.
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ABSTRACT The pine sawfly pheromone precursor 3,7-dimethyl-2-pentadecanol (diprionol) was quantified by gas chromatography in different body parts of virgin female Neodiprion sertifer. About one-third of the total amount (approx. 10 ng per... more
ABSTRACT The pine sawfly pheromone precursor 3,7-dimethyl-2-pentadecanol (diprionol) was quantified by gas chromatography in different body parts of virgin female Neodiprion sertifer. About one-third of the total amount (approx. 10 ng per female) was found in each of head + thorax, abdominal segments 1–3, and the remaining abdomen. Diprionol was also found in the respective parts of pupae, but in lower amounts. This suggests that at least the final steps of the pheromone biosynthesis take place in many parts of the body, possibly in the cuticle. The diprionol content remained relatively constant over the whole lifetime of virgin females. By using coupled gas chromatography-electroantennogram detection three active compounds in the acetylated female extract were observed. These corresponded to the pheromone, (2S,3S,7S)-diprionyl acetate, and its homologues with the chain shortened by one and two carbons respectively, as determined by gas chromatography-mass spectrometry. In addition, the homologue having a chain elongated by one carbon was found. The homologues occurred in amounts of 2–5% of the diprionyl acetate. When synthetic homologues were tested in the field, alone or in combination with diprionyl acetate, they were not behaviourally active to male sawflies, despite their electroantennogram activity. A threo-isomer of diprionol, most likely (2S,3R,7R), was present in the females in amounts less than 0.5% of the (2S,3S,7S)-content. The acetate of this threo-isomer is known as both synergist and inhibitor to the (2S,3S,7S)-isomer. trans-Perillenal was found in the abdominal segments 1–3 of both males and females and its possible biosynthetic relationship to diprionol is discussed.
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Abstract Oviposition in Spodoptera littoralis was strongly deterred by a mixture of six compounds, benzaldehyde and the five terpenes carvacrol, eugenol, nerolidol, phytol and thymol, identified from conspecific larval frass. If one of... more
Abstract Oviposition in Spodoptera littoralis was strongly deterred by a mixture of six compounds, benzaldehyde and the five terpenes carvacrol, eugenol, nerolidol, phytol and thymol, identified from conspecific larval frass. If one of the compounds was excluded from ...
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Insects show behavioural plasticity based on their physiological state. Deprivation from a resource will normally make them more responsive to it or to perform behaviour increasing the probability of encountering such a resource.... more
Insects show behavioural plasticity based on their physiological state. Deprivation from a resource will normally make them more responsive to it or to perform behaviour increasing the probability of encountering such a resource. Modulation of the olfactory system has been shown mainly in the central nervous system, but also in the periphery. In this study, antennal sensitivity of females of the Egyptian cotton leaf worm Spodoptera littoralis to different plant and sex pheromone odours was measured using electroantennography (EAG). Different mating status, age, and feeding status were used to investigate peripheral changes in olfactory responses. Virgin females were found to be more sensitive to plant odours and sex pheromone compared to mated females. Age also had an impact on antennal sensitivity, 2 and 4 days old females being more sensitive than just-emerged ones. Such an increase in sensitivity could be explained by maturation of olfactory receptor neurons after emergence or by an increase in motivation as the available expected life time remaining decreases. Finally, feeding status did not modify the antennal sensitivity of females. A peripheral modulation could thus be demonstrated in the olfactory system of female Spodoptera littoralis at certain life stages.
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Olfactory single sensillum responses of male and female caddisflies Rhyacophila nubila (Trichoptera: Rhyacophilidae) were examined with the tungsten penetration technique to investigate the presence of receptor neurons tuned to potential... more
Olfactory single sensillum responses of male and female caddisflies Rhyacophila nubila (Trichoptera: Rhyacophilidae) were examined with the tungsten penetration technique to investigate the presence of receptor neurons tuned to potential sex pheromone components. The compounds tested in the experiment were heptan-2-one, nonan-2-one, (R)-heptan-2-ol, and (R)-nonan-2-ol, which have all been found to be present in female abdominal glands, plus the two antipodes (S)-heptan-2-ol and (S)-nonan-2-ol. Four types of receptor neurons were found in equal proportions in males and females. One type responded primarily to heptan-2-one. A second type responded primarily to (R)-heptan-2-ol and a third type primarily to its enantiomer (S)-heptan-2-ol. The fourth type of receptor neuron responded to nonan-2-one, (R)-nonan-2-one, and (S)-nonan-2-ol, with a bias to nonan-2-one. The receptor neurons responding to the tested compounds made up a great majority of the contacted neurons in both males and females.
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... That receptor cells tuned to a behavioural antagonist may have a lower specificity than receptors for conspecific pheromone components is known also from other Lepidoptera, eg Agrotis segetum (Lofstedt et al., 1982) and Mamestra suasa... more
... That receptor cells tuned to a behavioural antagonist may have a lower specificity than receptors for conspecific pheromone components is known also from other Lepidoptera, eg Agrotis segetum (Lofstedt et al., 1982) and Mamestra suasa (Lucas and Renou, 1989). ...
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Electroantennographic and single sensillum recordings were performed on male pine sawfly, Neodiprion sertifer, antennae. Responses to the sex pheromone component (2S, 3S, 7S)- 3,7-dimethyl-2-pentadecenyl (diprionyl) acetate (SSS:OAc), to... more
Electroantennographic and single sensillum recordings were performed on male pine sawfly, Neodiprion sertifer, antennae. Responses to the sex pheromone component (2S, 3S, 7S)- 3,7-dimethyl-2-pentadecenyl (diprionyl) acetate (SSS:OAc), to the behavioral inhibitor (2S, 3R, 7R)-diprionyl acetate (SRR:OAc), to the six other enantiomers of diprionyl acetate, and to the biosynthetic precursor diprionol were recorded. Responses to trans-perillenal, a monoterpene identified in female gland extracts and to (2S, 3S, 7S)-diprionyl propionate (SSS:OPr), a field attractant for N. sertifer and some related sawfly species were also recorded. EAG recordings demonstrated a high antennal sensitivity to SSS:OAc and to SSS:OPr. A somewhat lower response was elicited by SRR:OAc. Single sensillum recordings revealed 8-12 different cells firing in each sensillum, corresponding to the number of cells observed in earlier morphological investigations. Out of these cells all, except one, responded to SSS:OAc and to SSS:OPr. No differences in the response to the two components could be observed. The largest amplitude cell in each sensillum was specifically tuned to the behavioral antagonist, SRR:OAc. The pheromone perception system encountered in male pine sawflies thus differs clearly from that observed in moths.
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This account describes novel mushroom body organization in a coleopteran insect, the African fruit chafer Pachnoda marginata. Each of its prominent mushroom bodies possesses a pair of simple calyces comprising two populations of Kenyon... more
This account describes novel mushroom body organization in a coleopteran insect, the African fruit chafer Pachnoda marginata. Each of its prominent mushroom bodies possesses a pair of simple calyces comprising two populations of Kenyon cells, the dendrites of which are organized into a central and an annular zone. Kenyon cells of the central zone extend their dendrites downward and toward the perimeter of the calyx. Their axon-like processes in the pedunculus are densely packed to make up a distinctive shaft of neuropil. Toward the front of the brain, the shafts, one from each calyx, bifurcate to provide a pair of subdivisions in the medial and vertical lobes. Dendrites of Kenyon cells supplying the annular zone extend from the calyx perimeter toward its center. Axons from the annular zones of both calyces together provide a sleeve of axons that ensheaths the two shafts. Sleeve axons bifurcate to provide a second pair of divisions in each of the lobes. These arrangements provide each lobe with a discrete representation of the two Kenyon cell populations of the two calyces. Kenyon cells supplying the central zone have dendritic morphologies reminiscent of class II clawed Kenyon cells that supply the gamma lobes in other taxa. Kenyon cells supplying axons to the sleeve are suggestive of class III Kenyon cell morphologies described from cockroaches and termites. Elaborate intrinsic neurons, comparable to exotic intrinsic neurons in the honey bee gamma lobes, have processes that interact with shaft axons. The present observations suggest that mushroom bodies of Pachnoda represent either a basal organization entirely lacking class I Kenyon cells or an evolutionary modification in which there is no clear morphological distinction of class I and II Kenyon cells. In either case, cellular organization in Pachnoda's mushroom body is simple compared with that of other taxa.
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Journal of Chemical Ecology, Vol. 19, No. 1, 1993 ... ELECTROPHYSIOLOGICAL AND BEHAVIORAL RESPONSES OF TURNIP MOTH MALES, Agrotis segetum 1 TO FLUORINATED PHEROMONE ANALOGS ... WU WENQI, 2 MARIE BENGTSSON, 3 BILL S. HANSSON, 2 TOMMY ...