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4632. Chemical cues mediating aphid location by natural enemies

Creator:
Michaud, J.P., Hatano, Eduard, Kunert, Grit, and Weisser , W.
Type:
article, model:article, and TEXT
Subject:
Aphid, natural enemies, host selection, semiochemicals, and infochemical
Language:
English
Description:
There is increasing evidence that chemical cues play a pivotal role in host selection by the natural enemies of aphids. We use Vinson's (1976) division of the host selection process into habitat location, host location and host acceptance for both parasitoids and predators and review what is known about the role of semiochemicals in aphid selection by natural enemies. For habitat location (i.e. detection of the host plant), volatiles emitted by plants after aphid attack have been described for a number of plant-aphid interactions. These synomones indicate not only the presence of an aphid host plant to the predator or parasitoid, but also the presence of aphids. Volatiles emitted from undamaged host plants are often attractive to aphid parasitoids, but less so for predators. Host location by the natural enemy on the food plant is guided by semiochemicals that mostly originate from the aphids, in particular aphid alarm pheromone, honeydew, or the smell of the aphid itself. Host acceptance is guided by contact chemicals for both predators and parasitoids. In parasitoids, host recognition may be based on visual cues or on contact chemicals on the aphid's cuticle, whereas host acceptance is ultimately based on as yet unknown substances within the aphid's hemolymph. While it appears that many predators and parasitoids are attracted to the same semiochemicals, synergistic and antagonistic interactions among chemical substances have only rarely been investigated. More research into model systems is needed, not only to identify important semiochemicals, but also to determine their range of attraction. Recent progress in the development of analytical techniques has created new opportunities to improve our understanding of the chemical ecology of aphid-natural enemy interactions in the coming years.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

4633. Chemical defence of the warningly coloured caterpillars of Methona themisto (Lepidoptera: Nymphalidae: Ithomiinae)

Creator:
Massuda, Kamila F. and Trigo, José R.
Type:
article, model:article, and TEXT
Subject:
Aposematism, Brunfelsia uniflora, Camponotus crassus, Gallus gallus domesticus, learning, Lycosa erythrognatha, predation, Solanaceae, and unpalatability
Language:
English
Description:
The caterpillars of the butterfly Methona themisto (Nymphalidae: Ithomiinae) are conspicuously coloured and feed exclusively on Brunfelsia uniflora (Solanaceae), a plant that is rich in secondary plant substances, which suggests the caterpillars are chemically protected against predators. Results of experiments indicate that predators determine the survival of Methona themisto caterpillars in the field and laboratory bioassays that this organism is eaten by ants and spiders but not chicks. Both the conspicuous orange and black striped colouration and chemical compounds of Methona themisto caterpillars seem to be related to protection against predation by visually hunting predators. Chicks ate proportionally more of the cryptically coloured 1st instar caterpillars than of the conspicuously coloured later instar caterpillars. That Methona themisto caterpillars are chemically defended is supported by the activity of the dichloromethanic extract of 5th instars in preventing predation by chicks. Caterpillars of Methona themisto are aposematic as they are both (1) unpalatable, and (2) their warning signal is easily recognized by potential predators. Chicks learned to avoid the aposematic 3rd or 5th instar caterpillars after one encounter. Mealworms painted to look like caterpillars were also rejected by chicks that had previously encountered Methona caterpillars. Naïve chicks did not avoid eating the painted mealworms, which indicates they do not innately avoid this specific colour pattern.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

4634. Chemical stability of assembly pheromone of argasid ticks (Ixodoidea: Argasidae)

Creator:
Dusbábek, František, Zahradníčková, Helena, and Šimek, Petr
Format:
print
Type:
model:internalpart and TEXT
Subject:
assembly pheromone, guanine, xanthine, hypoxanthine, uric acid, tick excreta, purine degradation, Argas persicus, and Omithodoros moubata
Language:
English
Description:
Chemical stability and aggregation activity of assembly pheromone of argasid ticks and its synthetic purine analogues were studied during long-lasting storage at room temperature as the potential components of attractant/acaricide mixtures. Guanine spherules from dry excreta of Omithodoros moubata Murray, 1877 were very stable in their chemical composition and did not suffer from purine degradation. However, an intensive purine conversion into uric acid occurred in samples of the fluid of the excreta of Argas persicus (Oken, 1818) and to a lesser extent also in an artificial mixture of synthetic guanine, xanthine and hypoxanthine in saline. The presence of bacteria Bacillus sp. and the moulds Talaromyces flavus (syn. Pénicillium dangeardii) and Aspergillus carbonarius, isolated from some samples, might explain the enzymic degradation of purines. The suspension of guanine hydrochloride in saline or in saline with ethanol (1 : 1 v/v) as a potential acaricide solvent, and with diatomaceous earth as the pheromone carrier, was very stable and no guanine degradation occurred. This proved to be suitable for potential use mixed with acaricides for tick control. The assembly of A. persicus males, on most of the substrates tested, was very high up to day 77 of experiment but decreased significantly on day 114-119 in samples of synthetic analogue of assembly pheromone variant 1 in which the absolute amount of guanine in solutions strongly decreased or disappeared completely.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4635. Chemical sympathectomy restores baroreceptor-heart rate reflex and heart rate variability in rats with chronic nitric oxide deficiency

Creator:
Chaswal, M., Das, J., Prasad, J., Katyal, A., and Fahim, M.
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, oxid dusnatý, nitric oxide, NG-nitro-L-arginine methyl ester, sympathectomy, 6-hydroxydopamine, autonomic dysfunction, 14, and 612
Language:
English
Description:
Nitric oxide (NO) plays a crucial role not only in regulation of blood pressure but also in maintenance of cardiac autonomic tone and its deficiency induced hypertension is accompanied by cardiac autonomic dysfunction. However, underlying mechanisms are not clearly defined. We hypothesized that sympathetic activation mediates hemodynamic and cardiac autonomic changes consequent to deficient NO synthesis. We used chemical sympathectomy by 6-hydroxydopamine to examine the influence of sympathetic innervation on baroreflex sensitivity (BRS) and heart rate variability (HRV) of chronic NG-nitro-L-arginine methyl ester (L-NAME) treated adult Wistar rats. BRS was determined from heart rate responses to changes in systolic arterial pressure achieved by intravenous administration of phenylephrine and sodium nitroprusside. Time and frequency domain measures of HRV were calculated from 5-min electrocardiogram recordings. Chronic L-NAME administration (50 mg/kg per day for 7 days orally through gavage) in control rats produced significant elevation of blood pressure, tachycardia, attenuation of BRS for bradycardia and tachycardia reflex and fall in time as well as frequency domain parameters of HRV. Sympathectomy completely abolished the pressor as well as tachycardic effect of chronic L-NAME. In addition, BRS and HRV improved after removal of sympathetic influence in chronic L-NAME treated rats. These results support the concept that an exaggerated sympathetic activity is the principal mechanism of chronic L-NAME hypertension and associated autonomic dysfunction., M. Chaswal, S. Das, J. Prasad, A. Katyal, M. Fahim., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4636. Cheminement d’un humaniste. Kitāb al-isrā’ ilā al-maqām al-asrā dans la pensée d’Ibn ‘Arabī (1165–1241)

Creator:
Wronecka, Joanna
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
islam, Ibn Arabi, Arab philosophy, Islamic mysticism, and religion
Language:
English
Description:
In the article “Cheminement d’un humaniste” the author presents the results of her research on a small treatise Kitāb al-isrā’ ilā maqām al-asrā (Nigh Journey). She established a critical edition of the text in Arabic on the basis of a comparison of the limited number of manuscripts available in Dār al-Kutub al Masrīyya in Cairo. She then translated “Kitāb al-isrā’” into Polish. Kitāb al-isrā’ is one of the most important early works, written by Ibn Arabi after his great visionary experience in Fez, in 1198. It describes in rhymed prose his mystical ascension, meeting in the spiritual realities of the prophets in the seven heavens and being brought to the fullest realization of his own reality. Ibn Arabi’s ascension is a dream, a vision of a heart. These divine events determine the way forward for his ultimate role as the perfect man (insān kāmil) or the Seal of Muhammadian Sainthood.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

4637. Chemotaxonomical characterisation of males of Bombus lucorum (Hymenoptera: Apidae) collected in the Czech Republic

Creator:
Urbanová, Klára, Valterová, Irena, Hovorka, Oldřich , and Kindl, Jiří
Type:
article, model:article, and TEXT
Subject:
Hymenoptera, Apidae, Bombus lucorum, bumblebees, marking pheromone, labial gland secretion, chemosystematics, and ethyl (Z)-9-tetradecenoate
Language:
English
Description:
Labial gland secretions of 26 males of the bumblebee Bombus lucorum (L.), collected in the Czech Republic, were analysed. The secretions consisted of 60 compounds; ethyl (Z)-9-tetradecenoate was the main component (average 53%). Although the males varied in colour, their labial gland secretions were similar in composition, which indicated they belonged to one species. Chemically the B. lucorum occurring in the Czech Republic correspond to the earlier described "blonde form" of this species.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

4638. Chen Chieh-jen´s artwork and post-1987 art in Taiwan: from the body as a political instrument to the recuperation of the Self

Creator:
Sanz Giménez, Susana
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Chen Chieh-jen, contemporary art in Taiwan, body, history, and politics
Language:
English
Description:
Chen Chieh-jen is currently the most renowned contemporary Taiwanese artist, participating in numerous worldwide art biennals and exhibitions. Firstly, this paper will narrate how Chen managed to become an artist, while, at the same time, an anylysis of Taiwan´s sociopolitical and cultural history will be presented. The analysis will be from an unusual viewpoint: that of Taiwanese contemporary art, a field of study marginalized by Western Scholars in Taiwanese Studies. The testimonies of its protagonists, Taiwanese artists, will also be included. Secondly, the lifting of a 40 year period of martial law in 1987 symbolizes the kickoff point for the development of contemporary Taiwanese art. Chen Chieh-jen, as many other Taiwanese artists, participated in this process. making use of his body to state his sociopolitical stance. This paper will demonstrate how the body became one of the main focal points in contemporary art in Taiwan. Having been hidden by censorship, the body was turned into an instrument of political condemnation, an even a key element in the local claim of Taiwanese identity. And finally, we will analyze how Chen Chien-jen developed his own artistic interpretation of the body, beginning with his political performances and moving onto the recovery of his personal identity and story through the medium of his black and white photographic series.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

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