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331.
Federico Cappa Claudia Bruschini Maria Cipollini Giuseppe Pieraccini Rita Cervo 《Die Naturwissenschaften》2014,101(2):149-152
The ability to discriminate among nestmates and non-nestmate is essential to defend social insect colonies from intruders. Over the years, nestmate recognition has been extensively studied in the honeybee Apis mellifera; nevertheless, the quantitative perceptual aspects at the basis of the recognition system represent an unexplored subject in this species. To test the existence of a cuticular hydrocarbons’ quantitative perception threshold for nestmate recognition cues, we conducted behavioural assays by presenting different amounts of a foreign forager’s chemical profile to honeybees at the entrance of their colonies. We found an increase in the explorative and aggressive responses as the amount of cues increased based on a threshold mechanism, highlighting the importance of the quantitative perceptual features for the recognition processes in A. mellifera. 相似文献
332.
333.
Claudia Dreller Robert E. Page Jr. M. Kim Fondrk 《Behavioral ecology and sociobiology》1999,45(3-4):227-233
Pollen storage in a colony of Apis mellifera is actively regulated by increasing and decreasing pollen foraging according to the “colony's needs.” It has been shown that
nectar foragers indirectly gather information about the nectar supply of the colony from nestmates without estimating the
amount of honey actually stored in the combs. Very little is known about how the actual colony need is perceived with respect
to pollen foraging. Two factors influence the need for pollen: the quantity of pollen stored in cells and the amount of brood.
To elucidate the mechanisms of perception, we changed the environment within normal-sized colonies by adding pollen or young
brood and measured the pollen-foraging activity, while foragers had either direct access to them or not. Our results show
that the amount of stored pollen, young brood, and empty space directly provide important stimuli that affect foraging behavior.
Different mechanisms for forager perception of the change in the environment are discussed.
Received: 13 June 1998 / Accepted after revision: 25 October 1998 相似文献
334.
Helena I. S. Nogueira Claudia Adduce Elsa Alves Mário J. Franca 《Environmental Fluid Mechanics》2014,14(2):519-540
The present work experimentally investigates the dynamics of unsteady gravity currents produced by lock-release of a saline mixture into a fresh water tank. Seven different experimental runs were performed by varying the density of the saline mixture in the lock and the bed roughness. Experiments were conducted in a Perspex flume, of horizontal bed and rectangular cross section, and recorded with a CCD camera. An image analysis technique was applied to visualize and characterize the current allowing thus the understanding of its general dynamics and, more specifically, of the current head dynamics. The temporal evolution of both head length and mass shows repeated stretching and breaking cycles: during the stretching phase, the head length and mass grow until reaching a limit, then the head becomes unstable and breaks. In the instants of break, the head aspect ratio shows a limit of 0.2 and the mass of the head is of the order of the initial mass in the lock. The average period of the herein called breaking events is seen to increase with bed roughness and the spatial periodicity of these events is seen to be approximately constant between runs. The rate of growth of the mass at the head is taken as a measure to assess entrainment and it is observed to occur at all stages of the current development. Entrainment rate at the head decreases in time suggesting this as a phenomenon ruled by local buoyancy and the similarity between runs shows independence from the initial reduced gravity and bed roughness. 相似文献
335.
Elaine S. Fileman Penelope K. Lindeque Rachel A. Harmer Claudia Halsband Angus Atkinson 《Marine Biology》2014,161(11):2479-2494
Meroplankton are seasonally important contributors to the zooplankton, particularly at inshore sites, yet their feeding ecology is poorly known relative to holoplankton. While several studies have measured feeding in decapod larvae, few studies have examined the feeding rates of decapod larvae on natural prey assemblages throughout the reproductive season. We conducted 8 feeding experiments with Necora puber, Liocarcinus spp. and Upogebia spp. zoea larvae collected from the L4 monitoring site off Plymouth (50°15.00′N, 4°13.02′W) during spring–summer 2009 and 2010. This period spanned moderate-to-high food availability (0.5–1.6 µg chl-a L?1), but a great range in food composition with small cells <20 µm dominating in 2010. Daily rations averaged 17, 60 and 22 % of body C for the 3 respective decapod species. Clearance rates differed according to prey type, and all 3 decapod genera showed evidence of selection of dinoflagellates. Importantly, small cells including nano- and pico-plankton were ingested, this being demonstrated independently by flow cytometric analysis of the feeding experiments and molecular analysis. PCR-based analysis of the haptophyte portion of the diet revealed ingestion of Isochrysis galbana by decapod larvae in the bottle incubations and Isochrysis galbana and Phaeocystis globosa by decapod larvae collected directly from the field. This study has shown that pico- and nano-sized plankton form an important supplement to the diverse and variable diet of decapod larvae. 相似文献
336.
Claudia Westhus Line V. Ugelvig Edouard Tourdot Jürgen Heinze Claudie Doums Sylvia Cremer 《Behavioral ecology and sociobiology》2014,68(10):1701-1710
Repeated pathogen exposure is a common threat in colonies of social insects, posing selection pressures on colony members to respond with improved disease-defense performance. We here tested whether experience gained by repeated tending of low-level fungus-exposed (Metarhizium robertsii) larvae may alter the performance of sanitary brood care in the clonal ant, Platythyrea punctata. We trained ants individually over nine consecutive trials to either sham-treated or fungus-exposed larvae. We then compared the larval grooming behavior of naive and trained ants and measured how effectively they removed infectious fungal conidiospores from the fungus-exposed larvae. We found that the ants changed the duration of larval grooming in response to both, larval treatment and their level of experience: (1) sham-treated larvae received longer grooming than the fungus-exposed larvae and (2) trained ants performed less self-grooming but longer larval grooming than naive ants, which was true for both, ants trained to fungus-exposed and also to sham-treated larvae. Ants that groomed the fungus-exposed larvae for longer periods removed a higher number of fungal conidiospores from the surface of the fungus-exposed larvae. As experienced ants performed longer larval grooming, they were more effective in fungal removal, thus making them better caretakers under pathogen attack of the colony. By studying this clonal ant, we can thus conclude that even in the absence of genetic variation between colony members, differences in experience levels of brood care may affect performance of sanitary brood care in social insects. 相似文献
337.
This paper considers the efforts of United Nations and international agencies to address the threats to Palestinian children arising from Israeli occupation. It contains an account of the reasons why agencies have failed, over many years, to prevent systematic violations by the Israeli authorities and settlers. The discussion is organised around two inter‐related domains: institutional and political. The paper argues that, in the occupied Palestinian territory (oPt), limitations to the ways in which child protection has been conceptualised and pursued in practice are abundantly evident. Nevertheless, political pressure by Western donor governments serves to constrain an approach to child protection that is more preventative in nature, that addresses more explicitly Israeli violations of international law, and that reflects the experience and aspirations of Palestinian children themselves. Ultimately, therefore, the failure to protect Palestinian children must be seen not only as a result of humanitarian miscalculation but also as a consequence of political strategy. 相似文献
338.
Alessandra Colombo Giuseppe Cappelletti Silvia Ardizzone Iolanda Biraghi Claudia L. Bianchi Daniela Meroni Carlo Pirola Francesca Spadavecchia 《Environmental Chemistry Letters》2012,10(1):55-60
Bisphenol A is an endocrine disruptor. Complete mineralization of bisphenol A is therefore a primary environmental issue.
Here, the combination of ozonation and photocatalysis by TiO2 is proposed for the degradation and final mineralization of bisphenol A. TiO2 films deposited onto two sides of an Al lamina show good stability and high surface roughness. We used a specific experimental
setup employing two facing ultraviolet lamps and TiO2 layers, together with an ozone flux. High-performance liquid chromatography–mass spectrometry determinations on bisphenol
A solutions sampled at different reaction times and Fourier Transform Infrared analyses of the oxide at the end of the reaction
were performed to study the reaction intermediates and the overall degradation mechanism. Our results show that pollutant
mineralization achieved with the combined method is far higher, of 55% in the case of 0.3 mM bisphenol A, than those obtained
by individual treatments such as photolysis (<3%), ozonation (6%), photocatalysis (6%), and by other combined processes: photolytic
ozonation (13%) and catalytic ozonation (15%). This finding is explained by the occurrence of highly synergistic effects. 相似文献
339.
Passive air sampling for persistent organic pollutants: introductory remarks to the special issue 总被引:1,自引:0,他引:1
Harner T Bartkow M Holoubek I Klanova J Wania F Gioia R Moeckel C Sweetman AJ Jones KC 《Environmental pollution (Barking, Essex : 1987)》2006,144(2):361-364
There have been a number of developments in the need, design and use of passive air samplers (PAS) for persistent organic pollutants (POPs). This article is the first in a Special Issue of the journal to review these developments and some of the data arising from them. We explain the need and benefit of developing PAS for POPs, the different approaches that can be used, and highlight future developments and needs. 相似文献
340.