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131.
Colony nutritional status modulates worker responses to foraging recruitment pheromone in the bumblebee Bombus terrestris 总被引:2,自引:1,他引:1
Mathieu Molet Lars Chittka Ralph J. Stelzer Sebastian Streit Nigel E. Raine 《Behavioral ecology and sociobiology》2008,62(12):1919-1926
Foraging activity in social insects should be regulated by colony nutritional status and food availability, such that both
the emission of, and response to, recruitment signals depend on current conditions. Using fully automatic radio-frequency
identification (RFID) technology to follow the foraging activity of tagged bumblebees (Bombus terrestris) during 16,000 foraging bouts, we tested whether the cue provided by stored food (the number of full honeypots) could modulate
the response of workers to the recruitment pheromone signal. Artificial foraging pheromones were applied to colonies with
varied levels of food reserves. The response to recruitment pheromones was stronger in colonies with low food, resulting in
more workers becoming active and more foraging bouts being performed. In addition to previous reports showing that in colonies
with low food successful foragers perform more excited runs during which they release recruitment pheromone and inactive workers
are more prone to leave the nest following nectar influx, our results indicate that evolution has shaped a third pathway that
modulates bumblebee foraging activity, thus preventing needless energy expenditure and exposure to risk when food stores are
already high. This new feedback loop is intriguing since it involves context-dependent response to a signal. It highlights
the integration of information from both forager-released pheromones (signal) and nutritional status (cue) that occurs within
individual workers before making the decision to start foraging. Our results support the emerging view that responses to pheromones
may be less hardwired than commonly acknowledged.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
132.
Thomas C. Ings Nigel E. Raine Lars Chittka 《Behavioral ecology and sociobiology》2009,63(8):1207-1218
Studies of innate colour preference and learning ability have focused on differences at the species level, rather than variation among populations of a single species. Initial strength and persistence of colour preferences are likely to affect colour choices of naïve flower visitors. We therefore study the influence of both the strength and persistence of innate colour preference (for blue) on an operant learning task (associating food reward with yellow flowers) in two populations of the bumblebee Bombus terrestris. We found that both strength and persistence of blue preference differed significantly between populations: B. terrestris dalmatinus had a weaker and less persistent blue preference than B. terrestris audax. These differences in preference also influenced learning performance. Considering only landing behaviours, one-trial learning occurred in the majority (73%) of bees, and was achieved sooner in B. terrestris dalmatinus because of its weaker blue preference. However, compared to landing behaviours the relative frequency of approach flights to rewarding and unrewarding flower types changed more slowly with task experience in both populations. When considering both approaches and landings, the rate of learning, following the first rewarded learning trial, was faster in B. terrestris audax than B. terrestris dalmatinus. However, the net effects of population differences in blue preference and learning dynamics result in similar final levels of task performance. Our results provide new evidence of behavioural differences among isolated populations within a single species, and raise intriguing questions about the ecological significance and adaptive nature of colour preference. 相似文献
133.
Hardiman Nigel Dietz Kristina Charlotte Bride Ian Passfield Louis 《Environmental management》2017,59(1):68-76
Environmental Management - Land managers of natural areas are under pressure to balance demands for increased recreation access with protection of the natural resource. Unintended dispersal of... 相似文献
134.
Testing the limits of social resilience in ant colonies 总被引:4,自引:0,他引:4
Sarah J. Backen A. B. Sendova-Franks Nigel R. Franks 《Behavioral ecology and sociobiology》2000,48(2):125-131
Social resilience is the ability of Leptothorax ant colonies to re-assemble after dissociation, as caused, for example, by an emigration to a new nest site. Through social
resilience individual workers re-adopt their spatial positions relative to one another and resume their tasks without any
time being wasted in worker respecialisation. Social resilience can explain how an efficient division of labour can be maintained
throughout the trials and tribulations of colony ontogeny including the, often substantial, period after the queen dies when
the ability to conserve worker social relationships may be essential for efficiency to be maintained. The mechanism underlying
social resilience is, therefore, expected to be robust even in the absence of many of the colony’s components, such as the
queen, the brood and even a large proportion of the workers. Such losses are likely, given the ecology of this genus. Using
sociotomy experiments, we found that social resilience can occur in the absence of the queen. Furthermore, the spatial component
of social resilience can occur even when the queen, the brood, as well as a large proportion of the workers, are all absent
simultaneously and hence many of the tasks are missing. We conclude, therefore, that social resilience is indeed robust. This
does not, however, preclude worker flexibility in response to changes in task supply and demand. We propose a possible sorting
mechanism based on worker mobility levels which might explain the robustness underlying this phenomenon.
Received: 25 October 1999 / Accepted: 1 April 2000 相似文献
135.
Nigel N. Clark David L. McKain 《Journal of the Air & Waste Management Association (1995)》2013,63(3):432-442
ABSTRACT In-use emissions from vehicles using heavy-duty diesel engines can be significantly higher than the levels obtained during engine certification. These higher levels may be caused by a combination of degradation of engine components, poor engine maintenance, degradation or failure of emissions after-treatment devices, and engine and emissions system tampering. A direct comparison of in-use vehicle emissions with engine certification levels, however, is not possible without removing an engine from the vehicle in order to perform engine dynamometer emissions testing. The goal of this research was to develop a chassis test procedure that mimics the engine performance, and as such the expected emissions levels, from the engine certification emissions test prescribed in the U.S. Code of Federal Regulations. Emissions measurements were taken from two engines during testing on an engine dynamometer using the transient heavy-duty Federal Test Procedure (FTP). Additionally, each engine was installed in an appropriate vehicle, and emissions measurements were taken using a chassis dynamometer while employing a vehicle driving schedule 相似文献
136.
Noa Pinter-Wollman Julia Hubler Jo-Anne Holley Nigel R. Franks Anna Dornhaus 《Behavioral ecology and sociobiology》2012,66(10):1407-1420
How social insect colonies behave results from the actions of their workers. Individual variation among workers in their response to various tasks is necessary for the division of labor within colonies. A worker may be active in only a subset of tasks (specialist), perform all tasks (elite), or exhibit no particular pattern of task activity (idiosyncratic). Here we examine how worker activity is distributed among and within tasks in ants of the genus Temnothorax. We found that workers exhibited elitism within a situation, i.e., in particular sets of tasks, such as those associated with emigrations, nest building, or foraging. However, there was weak specialization for working in a particular situation. A few workers exhibited elitism across all situations, i.e., high performance in all tasks in all situations. Within any particular task, the distribution of activity among workers was skewed, with few ants performing most of the work and most ants performing very little of the work. We further found that workers persisted in their task preference over days, with the same individuals performing most of the work day after day. Interestingly, colonies were robust to the removal of these highly active workers; they were replaced by other individuals that were previously less active. This replacement was not short-lived; when the removed individuals were returned to the colony, not all of them resumed their prior high activity levels, and not all the workers that replaced them reduced their activity. Thus, even though some workers specialize in tasks within a particular situation and are persistent in performing them, task allocation in a colony is plastic and colonies can withstand removal of highly active individuals. 相似文献
137.
Keryn I. Paul John S. Larmour Stephen H. Roxburgh Jacqueline R. England Micah J. Davies Hamish D. Luck 《Environmental monitoring and assessment》2017,189(8):416
Stem diameter is one of the most common measurements made to assess the growth of woody vegetation, and the commercial and environmental benefits that it provides (e.g. wood or biomass products, carbon sequestration, landscape remediation). Yet inconsistency in its measurement is a continuing source of error in estimates of stand-scale measures such as basal area, biomass, and volume. Here we assessed errors in stem diameter measurement through repeated measurements of individual trees and shrubs of varying size and form (i.e. single- and multi-stemmed) across a range of contrasting stands, from complex mixed-species plantings to commercial single-species plantations. We compared a standard diameter tape with a Stepped Diameter Gauge (SDG) for time efficiency and measurement error. Measurement errors in diameter were slightly (but significantly) influenced by size and form of the tree or shrub, and stem height at which the measurement was made. Compared to standard tape measurement, the mean systematic error with SDG measurement was only ?0.17 cm, but varied between ?0.10 and ?0.52 cm. Similarly, random error was relatively large, with standard deviations (and percentage coefficients of variation) averaging only 0.36 cm (and 3.8%), but varying between 0.14 and 0.61 cm (and 1.9 and 7.1%). However, at the stand scale, sampling errors (i.e. how well individual trees or shrubs selected for measurement of diameter represented the true stand population in terms of the average and distribution of diameter) generally had at least a tenfold greater influence on random errors in basal area estimates than errors in diameter measurements. This supports the use of diameter measurement tools that have high efficiency, such as the SDG. Use of the SDG almost halved the time required for measurements compared to the diameter tape. Based on these findings, recommendations include the following: (i) use of a tape to maximise accuracy when developing allometric models, or when monitoring relatively small changes in permanent sample plots (e.g. National Forest Inventories), noting that care is required in irregular-shaped, large-single-stemmed individuals, and (ii) use of a SDG to maximise efficiency when using inventory methods to assess basal area, and hence biomass or wood volume, at the stand scale (i.e. in studies of impacts of management or site quality) where there are budgetary constraints, noting the importance of sufficient sample sizes to ensure that the population sampled represents the true population. 相似文献
138.
Nigel N. Clark Ronald P. Jarrett Christopher M. Atkinson 《Journal of the Air & Waste Management Association (1995)》2013,63(9):76-84
ABSTRACT Diesel particulate matter (PM) is a significant contributor to ambient air PM10 and PM2.5 particulate levels. In addition, recent literature argues that submicron diesel PM is a pulmonary health hazard. There is difficulty in attributing PM emissions to specific operating modes of a diesel engine, although it is acknowledged that PM production rises dramatically with load and that high PM emissions occur during rapid load increases on turbocharged engines. Snap-acceleration tests generally identify PM associated with rapid transient operating conditions, but not with high load. To quantify the origin of PM during transient engine operation, continuous opacity measurements have been made using a Wager 650CP full flow exhaust opacity meter. Opacity measurements were taken while the vehicles were operated over transient driving cycles on a chassis dynamometer using the West Virginia University (WVU) Transportable Heavy Duty Vehicle Emissions Testing Laboratories. Data were gathered from Detroit Diesel, Cummins, Caterpillar, and Navistar heavy-duty (HD) diesel engines. Driving cycles used were the Central Business District (CBD) cycle, the WVU 5-Peak Truck cycle, the WVU 5-Mile route, and the New York City Bus (NYCB) cycle. Continuous opacity measurements, integrated over the entire driving cycle, were compared to total integrated PM mass. In addition, the truck was subjected to repeat snap-acceleration tests, and PM was collected for a composite of these snap-acceleration tests. Additional data were obtained from a fleet of 1996 New Flyer buses in Flint, MI, equipped with electronically controlled Detroit Diesel Series 50 engines. Again, continuous opacity, regulated gaseous emissions, and PM were measured. The relationship between continuous carbon monoxide (CO) emissions and continuous opacity was noted. In identifying the level of PM emissions in transient diesel engine operation, it is suggested that CO emissions may prove to be a useful indicator and may be used to apportion total PM on a continuous basis over a transient cycle. The projected continuous PM data will prove valuable in future mobile source inventory prediction. 相似文献
139.
This paper summarises the methodology and results of work involved in the investigation of energy demand in six Chinese villages included in the SUCCESS Project. The procedures used to collect data associated with local energy demand are explained and the approach to data analysis is explained. Results are provided in terms for delivered energy consumption, as an indicator of energy demand; primary energy consumption, as an indicator of energy resource depletion; and carbon dioxide emissions, as an indicator of global climate change. Similarities and differences between results for this sample of villages are considered. The important causes of differences in results are investigated. 相似文献
140.
Traumatic events are a particular type of stressor that may affect police officers engaged in front line duties. In this study, specific types of social support predicted to buffer the psychological and physical health effects of trauma are drawn from theory and empirical evidence in the area of post‐traumatic stress. Social support, measured as the content of communication, and the ease of talking about trauma was tested with 527 working police officers who responded to a questionnaire survey. Hierarchical regression analysis showed that the communication variables contributed to the variance in post‐traumatic stress disorder and physical symptoms with differential effects for different aspects of communication. Analysis of the effects of traumatic stress on symptoms for sub‐groups at different levels of communication showed that some types of communication, such as the ease of talking about trauma or positive communications about work, moderate the effects of stress for police officers, in that higher levels are associated with a weaker trauma–strain relationship. However, some types of communication buffered stress only at moderate levels and other types may not be protective. These results are discussed in terms of the types and sources of social support that are likely to buffer post‐traumatic stress at work. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献