| 1. |
- Anton, Sylvia, et al.
(författare)
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Central nervous processing of sex pheromones in two strains of the European corn borer Ostrinia nubilalis (Lepidoptera : Pyralidae)
- 1997
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Ingår i: Journal of Experimental Biology. - 0022-0949. ; 200:7, s. 1073-1087
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Tidskriftsartikel (refereegranskat)abstract
- Antennal lobe neurones were investigated in the pyralid moth Ostrinia nubilalis using intracellular recording and staining techniques. Response characteristics of antennal lobe neurones from males in the so-called E and Z strains, in F1 hybrids and in parental backcrosses were studied. The antennal lobe of a male O. nubilalis comprises approximately 30 ordinary glomeruli and three enlarged glomeruli making up the macroglomerular complex (MGC). Receptor neurones enter the antennal lobe via the antennal nerve and arborize in single glomeruli. Intracellularly stained, pheromone-responding projection neurones in both parental strains arborized in different glomeruli within the MGC, irrespective of their response characteristics. Neurones were grouped according to their specificity to single pheromone components and to pheromone blends. Component-specific, blend-specific and generalist neurones were found. Specificity only occurred at low stimulus concentrations and disappeared as concentrations increased. Although all neuronal types were present in both pheromone strains and crossings, differences in abundance and sensitivity were found. In the parental strains, neurones responding to the major pheromone component and to the respective strain-specific blend were more abundant than neurones responding to the minor component and the blend produced by the other strain. Neurones investigated in ZxE hybrids responded similarly to those of E-strain males, whereas neurones in EZxZ paternal backcrosses responded similarly to those of Z males. In the hybrids and paternal backcrosses, hybrid-blend-specific neurones were present that were not found in parental-strain males.
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| 2. |
- Anton, Sylvia, et al.
(författare)
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Developmental changes in the structure and function of the central olfactory system in gregarious and solitary desert locusts
- 2002
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Ingår i: Microscopy Research and Technique. - : Wiley. - 1059-910X .- 1097-0029. ; 56:4, s. 281-291
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Desert locusts are guided by olfactory cues in different behavioural contexts. In order to understand the basis for the variable olfactory guided behaviour displayed by different developmental stages and by solitary and gregarious locusts, we investigated their central olfactory system with neuroanatomical and neurophysiological methods. The primary olfactory centre of the brain, the antennal lobe (AL), increases in size during development due to an increased number and size of glomeruli. These glomeruli are innervated by a constant number of projection neurons that display increased dendritic arborizations during the development of the locust. The anatomical parameters do not differ between gregarious and solitary locusts, In parallel with the observed neuroanatomical changes, neurophysiological changes in response spectra and response specificity of AL neurons were found. During development, the percentage of neurons responding specifically to aggregation pheromone components decreases, whereas an increase in both pheromone-generalists and plant-pheromone generalist neurons is observed. The percentage of neurons responding to green leaf volatiles, however, remains constant. A decrease in the number of nymph blend-specific neurons was also observed. Our data show that anatomical and physiological properties of the AL and its neurons to a large extent reflect the changes in olfactory guided behaviour during development and between phases. The majority of our results are also in accordance with findings that the number of olfactory receptor neurons increases during development, resulting in increasing convergence on AL neurons.
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| 3. |
- Gadenne, C, et al.
(författare)
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Central processing of sex pheromone stimuli is differentially regulated by juvenile hormone in a male moth
- 2000
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Ingår i: Journal of Insect Physiology. - 1879-1611. ; 46:8, s. 1195-1206
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In the male moth, Agrotis ipsilon, the neuronal basis for juvenile hormone (JH)-linked modulation of sex pheromone responsiveness was investigated following stimulation of the antenna with i) an extract of female pheromone gland, ii) the synthetic pheromone blends from A. ipsilon and a closely related species, A. segetum, and iii) single components of the A. ipsilon blend. Response characteristics of olfactory interneurons were studied in the antennal lobe (AL) at different ages and with manipulated JH levels using intracellular recording techniques. Blend-specific, generalist and component-specific neurons were identified and described according to their response pattern. The proportion of low threshold AL interneurons increased significantly with age for all stimuli tested. Changes were, however, less pronounced for the minor single components. The proportion of low threshold AL interneurons in allatectomized (JH-deprived) mature males was significantly lower for all stimuli than in intact mature males. A large proportion of low threshold AL interneurons responding to the pheromone blends, but not as pronounced for single pheromone components, could be restored/induced by injecting JH either into JH-deprived mature males or into young immature males. The specificity for the species-specific blend compared to the A. segetum blend increased with age and JH injections.
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| 4. |
- Gadenne, C, et al.
(författare)
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Transient post-mating inhibition of behavioural and central nervous responses to sex pheromone in an insect
- 2001
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 268:1476, s. 1631-1635
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Tidskriftsartikel (refereegranskat)abstract
- Mating is costly for both male and female insects and should therefore only occur if it is likely to be successful. Within one scotophase, which is the dark period of the light cycle, male moths can only produce one single spermatophore, which is transferred to the female during mating. Remating within the same scotophase would thus be unsuccessful. We tested the hypothesis that newly mated males of the moth Agrotis ipsilon have developed an energy-saving strategy based on the transient inhibition of their sexual behaviour, thus avoiding unsuccessful remating. Agrotis ipsilon males do not copulate more than once during the same scotophase. Moreover, newly mated males do not respond behaviourally to the female sex pheromone although electroantennograms showed that their peripheral olfactory system is fully functional. However, intracellular recordings of antennal lobe neurons showed that the sensitivity for the synthetic sex pheromone blend decreased as compared with that of unmated males. Both the sexual behaviour and the sensitivity of the antennal lobe neurons were restored when tested during the next scotophase. Our results show a fast, transient neuronal plasticity that 'switches off' the olfactory system, which could prevent males from mating unsuccessfully.
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| 5. |
- Greiner, Birgit, et al.
(författare)
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Central processing of plant volatiles in Agrotis ipsilon males is age-independent in contrast to sex pheromone processing.
- 2002
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Ingår i: Chemical Senses. - 1464-3553. ; 27:1, s. 8-45
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Tidskriftsartikel (refereegranskat)abstract
- Male moths rely on female sex pheromones to find their mating partner and on plant volatiles for the detection of food sources. In the noctuid moth, Agrotis ipsilon, plasticity of central sex pheromone processing has been shown previously in the antennal lobe. The sensitivity of antennal lobe interneurons increases with age and juvenile hormone level. Here we investigated whether age affects not only central sex pheromone processing, but also central processing of plant volatiles in A. ipsilon males. Intracellular recordings of antennal lobe interneurons were made in males of different ages after stimulation of the antennae with seven different plant volatiles. The sensitivity and specificity of the antennal lobe interneurons for any of the plant volatiles tested did not change with age. From these results we conclude that the sensitivity of the antennal lobe interneurons involved in central plant volatile processing is age-independent and that the action of juvenile hormone is specific for central sex pheromone processing in A. ipsilon males.
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| 6. |
- Hansson, Bill S, et al.
(författare)
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Function and Morphology of the Antennal Lobe: New Developments
- 2000
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Ingår i: Annual Review of Entomology. - : Annual Reviews. - 0066-4170 .- 1545-4487. ; 45, s. 203-231
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The antennal lobe of insects has emerged as an excellent model for olfactory processing in the CNS. In the present review we compile data from areas where substantial progress has been made during recent years: structure-function relationships within the glomerular array, integration and blend specificity, time coding and the effects of neuroactive substances and hormones on antennal lobe processing.
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| 7. |
- Ignell, Rickard, et al.
(författare)
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Juvenile-hormone-mediated plasticity of aggregation behaviour and olfactory processing in adult desert locusts
- 2001
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Ingår i: Journal of Experimental Biology. - 1477-9145. ; 204:2, s. 249-259
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Tidskriftsartikel (refereegranskat)abstract
- In desert locusts Schistocerca gregaria, aggregation behaviour is elicited by aggregation pheromones. In this study, we show that the behavioural response to the major and most potent adult aggregation pheromone component, phenylacetonitrile, is age- and juvenile-hormone-dependent. Furthermore, we show that juvenile hormone influences the responsiveness of olfactory interneurons in the antennal lobe to aggregation pheromone, whereas the responsiveness of antennal receptor neurons is not changed. Old locusts and locusts injected with juvenile hormone, in contrast to young locusts and locusts deprived of juvenile hormone through allatectomy, i.e. after surgical removal of the gland producing this hormone, do not display any aggregation behaviour, as indicated by long-term behavioural observations. The lack of positive olfactory-guided behaviour coincides with an impairment of the central olfactory system, which displays a lower number of neurons responding to aggregation pheromone. Indirect and direct actions of juvenile hormone at different levels of the central nervous system may thus contribute to the regulation and modulation of behavioural responsiveness in the locust.
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| 8. |
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| 9. |
- Ignell, Rickard, et al.
(författare)
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The Antennal Lobe of Orthoptera - Anatomy and Evolution
- 2001
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Ingår i: Brain, Behavior and Evolution. - : S. Karger AG. - 0006-8977 .- 1421-9743. ; 57:1, s. 1-17
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The first odor-processing neuropils of insects comprise glomeruli, islets of neuropil, that are supplied by olfactory receptor neurons and give rise to efferent axons to higher brain centers. Glomeruli size and organization varies in a taxon-specific manner across the Insecta, suggesting possible correlates between their organization and chemosensory behaviors in different insect groups. Comparative studies of antennal lobe glomeruli within the Orthoptera have been used to infer how the various taxon-specific arrangements of odorant-processing structures (glomeruli) might have evolved. The cellular arrangements in glomeruli have been surveyed using anterograde filling and Golgi impregnation of antennal receptor neurons projecting to the antennal lobe in Stenopelmatidae, Tettigoniidae, Gryllidae, Tetrigidae and Acrididae. These taxa, which represent the two sub-orders of Orthoptera, reveal a high correlation between the neural architecture of the glomeruli and structures within the glomeruli. Using a recent molecular phylogeny of the Orthoptera we have mapped the occurrence of glomerular characteristics to infer the evolution of antennal lobe structures in orthopterans. The functional implications of these results are discussed.
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| 10. |
- Ignell, Rickard, et al.
(författare)
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The maxillary palp sensory pathway of Orthoptera
- 2001
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Ingår i: Arthropod Structure & Development. - 1467-8039. ; 29:4, s. 295-305
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Tidskriftsartikel (refereegranskat)abstract
- Primary sensory projections and arborisations of higher-order neurons associated with the maxillary palps were examined in Tettigoniidae, Gryllidae, Tetrigidae and Acrididae representing the two sub-orders of Orthoptera, Ensifera and Caelifera. Anterograde filling and Golgi impregnation of maxillary receptor neurons revealed two patterns of innervation, the ensiferous and the caeliferous type. In both ensiferans and caeliferans, receptor neurons arborised within the tritocerebrum, the antennal motor- and mechano-sensory centre and the lobus glomerulatus. In ensiferans, additional areas of innervation were found in the lobus glomerulatus and in a previously undescribed neuropil, here referred to as the accessory lobus glomerulatus. In relation to the anatomical data a putative functional segregation of the neuropil into gustatory-, olfactory- and mechano-sensory centres is implied.
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