bluuebunny/crossref_metadata_2025_split huggingface dataset:
Teretrius nigrescens against larger grain borer Prostephanus truncatus in African maize stores: biological control at work?
Authors: Holst Niels , Meikle William G. 
Published: December 2010

Summary

Following the accidental introduction of the bostrichid beetle Prostephanus truncatus into East and West Africa around 1980, a classical biological control campaign was launched in 1991; the histerid beetle Teretrius nigrescens was released as a biocontrol agent to prevent the destructive outbreak of the pest in small‐farm maize stores. However, while the campaign has been ongoing, so has discussion in the scientific community about the merits of this campaign and its chances of success.
From published and unpublished data from experimental maize stores in Benin, West Africa, we derived statistical models describing the in‐store insect population dynamics, and were thus able to point out significant biological interactions and to explain the observed lack of biological control.
We found that (i) T. nigrescens reduced significantly the population growth rate of both P. truncatus and the non‐target pest, the weevil Sitophilus zeamais; (ii) T. nigrescens displayed a positive numerical response to both prey species, P. truncatus and S. zeamais; (iii) asymmetric competition existed between the two prey species, S. zeamais was negatively affected by P. truncatus but not vice versa; (iv) T. nigrescens and S. zeamais displayed negative intraspecific density‐dependence whereas P. truncatus was resource‐limited.
We conclude that classical biological control with T. nigrescens is not likely to become successful, mainly due to the predator's intraspecific density‐dependence and its low population growth rate compared with its prey. We recommend that further research on P. truncatus integrated pest management takes into account the farmer as an active agent managing the store.
Synthesis and applications. When biocontrol does not result in satisfactory pest control, as in the case of P. truncatus, farmers should learn how to scout for the pest and take action when a need is detected. In areas where the pest is usually only a minor problem, the agricultural extension service should consider setting up a simple early warning system for their region. When attempts at classical biological control remain unsuccessful, as in the case of P. truncatus now for 10 years, policy‐makers should prioritize training of extension service and farmers in integrated pest management techniques (e.g. need‐based use of insecticides) as a necessary supplement to biocontrol.
Modelling the daily food requirements of wintering great cormorants: a bioenergetics tool for wildlife management
Authors: Gremillet David , Wright Gordon , Lauder ALAN. , Carss David N. , Wanless Sarah 
Published: December 2010

Summary

Great cormorants Phalacrocorax carbo, Linnaeus are large piscivorous birds which occur in Asia, Australia, Africa, Europe and North America. Their European breeding population has increased by at least 15% per annum over the last 15 years, reaching a total of c. 200 000 pairs in the late 1990s. There are concerns that this increase is adversely affecting freshwater fish populations throughout Europe, but real assessment requires a detailed knowledge of cormorant food requirements.
The daily food intake (DFI) of great cormorants has been measured during the breeding season, but little is known about DFI in winter when these poorly insulated birds experience consistently low temperatures. DFI is likely to vary widely according to abiotic and biotic conditions, making predictions about impact particularly difficult.
We modelled DFI for great cormorants wintering at Loch Leven, Scotland, using behavioural data recorded via radio‐tracking of free‐ranging individuals, metabolic measurements obtained from captive birds, and published data. DFI was estimated to be 672 g day−1 (predicted maximum range 441–1095 g day−1), values similar to DFI of great cormorants breeding under temperate conditions and of other aquatic bird species.
During winter great cormorants at Loch Leven decreased their average dive time and increased dive efficiency (higher proportion of time spent underwater). They nonetheless spent 130 min day−1 in the water and allocated more than a third of their daily energy budget to diving.
Synthesis and applications: In view of the need for the sound management of cormorant populations, we present a general bioenergetics model, based on simple behavioural and dietary inputs, that computes an estimate of DFI outside the breeding season for a range environmental conditions and habitats. An interactive computer programme for this model is available (http://www.cepe.c‐strasbourg.fr) to help scientists and managers estimate local values for average, minimum and maximum DFI.
Influence of mechanical cutting and pathogen application on the performance and nutrient storage of Cirsium arvense
Authors: Kluth Stephanie , Kruess Andreas , Tscharntke Teja 
Published: December 2010

Summary 1. In order to develop an effective biological control technique, the influence of mechanical and pathogen treatments on performance and nutrient storage of the weed creeping thistle Cirsium arvense was studied over a 2‐year period. To our knowledge, this is the first study to evaluate the effect of a combination of cutting and application of the rust Puccinia punctiformis as a possible biocontrol organism on thistles. 2. We conducted a complete two‐factorial design using potted plants, with the application of the rust and cutting of thistles as the treatment factors. Treatments were applied once every year in June. 3. Inoculation reduced above‐ground biomass in the first year. First year cutting reduced the number of thistle shoots, but stimulated compensatory growth with an increased growth rate and biomass. Only a second year cutting treatment significantly reduced above‐ and below‐ground biomass, despite an increased growth rate. 4. The number of flower heads was strongly reduced by both cutting and combined treatments. The proportion of fertile flower heads was increased by cutting, whereas the combination treatment strongly reduced it. 5. Analysing storage nutrients, starch concentrations did not differ among treatments. Cutting reduced sugar concentrations, but pathogen infection tended to increase concentrations, resulting in significant interaction effects. Cutting also reduced below‐ground carbon concentrations, but the carbon : nitrogen ratio was not influenced. 6. Synthesis and applications. The traditional mechanical technique of cutting was shown to be effective in reducing plant reproductive success and concentration of storage nutrients. Additional infection with a plant pathogen further restricted sexual reproduction, indicating that combined treatments may be more effective for biological control of perennial weed species. Whilst further studies are needed to establish P. punctiformis as a mycoherbicide, some synergism between repeated cutting and rust inoculation indicates that there is potential for a biological approach to the control of creeping thistle.
North Atlantic summers have warmed more than winters since 1353, and the response of marine zooplankton
Authors: Kamenos Nicholas A. 
Published: December 2010

Modeling and measurements show that Atlantic marine temperatures are rising; however, the low temporal resolution of models and restricted spatial resolution of measurements (
i
) mask regional details critical for determining the rate and extent of climate variability, and (
ii
) prevent robust determination of climatic impacts on marine ecosystems. To address both issues for the North East Atlantic, a fortnightly resolution marine climate record from 1353–2006 was constructed for shallow inshore waters and compared to changes in marine zooplankton abundance. For the first time summer marine temperatures are shown to have increased nearly twice as much as winter temperatures since 1353. Additional climatic instability began in 1700 characterized by ∼5–65 year climate oscillations that appear to be a recent phenomenon. Enhanced summer-specific warming reduced the abundance of the copepod
Calanus finmarchicus
, a key food item of cod, and led to significantly lower projected abundances by 2040 than at present. The faster increase of summer marine temperatures has implications for climate projections and affects abundance, and thus biomass, near the base of the marine food web with potentially significant feedback effects for marine food security.
X-RAY EMISSION FROM OPTICALLY SELECTED RADIO-INTERMEDIATE AND RADIO-LOUD QUASARS
Authors: Miller B. P. , Brandt W. N. , Schneider D. P. , Gibson R. R. , Steffen A. T. , Wu Jianfeng 
Published: December 2010

ABSTRACT
We present the results of an investigation into the X-ray properties of radio-intermediate and radio-loud quasars (RIQs and RLQs, respectively). We combine large, modern optical (e.g., SDSS) and radio (e.g., FIRST) surveys with archival X-ray data from Chandra, XMM-Newton, and ROSAT to generate an optically selected sample that includes 188 RIQs and 603 RLQs. This sample is constructed independently of X-ray properties but has a high X-ray detection rate (85%); it provides broad and dense coverage of the ℓ–z plane, including at high redshifts (22% of objects have z = 2–5), and it extends to high radio-loudness values (33% of objects have R* = 3–5, using logarithmic units). We measure the “excess” X-ray luminosity of RIQs and RLQs relative to radio-quiet quasars (RQQs) as a function of radio loudness and luminosity, and parameterize the X-ray luminosity of RIQs and RLQs both as a function of optical/UV luminosity and also as a joint function of optical/UV and radio luminosity. RIQs are only modestly X-ray bright relative to RQQs; it is only at high values of radio loudness (R* ≳ 3.5) and radio luminosity that RLQs become strongly X-ray bright. We find no evidence for evolution in the X-ray properties of RIQs and RLQs with redshift (implying jet-linked IC/CMB emission does not contribute substantially to the nuclear X-ray continuum). Finally, we consider a model in which the nuclear X-ray emission contains both disk/corona-linked and jet-linked components and demonstrate that the X-ray jet-linked emission is likely beamed but to a lesser degree than applies to the radio jet. This model is used to investigate the increasing dominance of jet-linked X-ray emission at low inclinations.
A Bayesian approach for estimating vertical chlorophyll profiles from satellite remote sensing: proof-of-concept
Authors: Williamson Robert , Field John G. , Shillington Frank A. , Jarre Astrid , Potgieter Anet 
Published: December 2010

Abstract
Williamson, R., Field, J. G., Shillington, F. A., Jarre, A., and Potgieter, A. 2011. A Bayesian approach for estimating vertical chlorophyll profiles from satellite remote sensing: proof-of-concept. – ICES Journal of Marine Science, 68: 792–799. A proof-of-concept demonstration is presented using a novel method for estimating vertical distributions of chlorophyll a (Chl a) from archives of data from ships, combined with remotely sensed data of sea surface temperature, surface Chl a, and wind (U and V vectors) from satellites. Our study area has contrasting hydrographic regimes that include the dynamic southern Benguela upwelling system and the stratified waters of the Agulhas Bank. Cluster analysis is used to identify “typical” Chl a profiles from an archive of profiles recorded in 2002–2008. Bayesian networks were then used to relate characteristic profiles to remotely sensed surface features, subregions, seasons, and depths. The proposed method could be used to predict daily Chl a profiles for each pixel of a satellite image to estimate biomass and subsurface light fields, and these combined with a light algorithm to model primary production for the Benguela large marine ecosystem.
Somatic Complaints in Childhood Functional Abdominal Pain Are Associated With Functional Gastrointestinal Disorders in Adolescence and Adulthood
Authors: Dengler‐Crish Christine M , Horst Sara N , Walker Lynn S 
Published: December 2010

ABSTRACTObjectives:Nongastrointestinal (non‐GI) somatic complaints are common in children and adults with functional gastrointestinal disorders (FGIDs). The aim of the present study was to determine whether non‐GI somatic complaints in children with functional abdominal pain (FAP) were associated with FGIDs in adolescence and young adulthood.Patients and Methods:In a prospective clinic‐based study, children and adolescents (ages 8–16 years) with FAP (n = 188) and well controls (n = 61) completed a validated measure of somatic symptoms. Participants were assessed 4 to 15 years later (as older adolescents and young adults) for presence of current FGIDs as defined by the Rome III criteria.Results:Of the 188 youths with pediatric FAP, 35.6% met criteria for FGIDs at follow‐up. Initial levels of non‐GI somatic symptoms were significantly higher in pediatric FAP participants who subsequently met criteria for FGIDs at follow‐up compared with controls and pediatric FAP participants who did not meet criteria for FGIDs at follow‐up.Conclusions:The association of non‐GI somatic symptoms with FAP in children may identify a group that is at risk for FGIDs later in life.
VirtualLeaf: An Open-Source Framework for Cell-Based Modeling of Plant Tissue Growth and Development
Authors: Merks Roeland M.H. , Guravage Michael , Inzé Dirk , Beemster Gerrit T.S. 
Published: December 2010

AbstractPlant organs, including leaves and roots, develop by means of a multilevel cross talk between gene regulation, patterned cell division and cell expansion, and tissue mechanics. The multilevel regulatory mechanisms complicate classic molecular genetics or functional genomics approaches to biological development, because these methodologies implicitly assume a direct relation between genes and traits at the level of the whole plant or organ. Instead, understanding gene function requires insight into the roles of gene products in regulatory networks, the conditions of gene expression, etc. This interplay is impossible to understand intuitively. Mathematical and computer modeling allows researchers to design new hypotheses and produce experimentally testable insights. However, the required mathematics and programming experience makes modeling poorly accessible to experimental biologists. Problem-solving environments provide biologically intuitive in silico objects (“cells”, “regulation networks”) required for setting up a simulation and present those to the user in terms of familiar, biological terminology. Here, we introduce the cell-based computer modeling framework VirtualLeaf for plant tissue morphogenesis. The current version defines a set of biologically intuitive C++ objects, including cells, cell walls, and diffusing and reacting chemicals, that provide useful abstractions for building biological simulations of developmental processes. We present a step-by-step introduction to building models with VirtualLeaf, providing basic example models of leaf venation and meristem development. VirtualLeaf-based models provide a means for plant researchers to analyze the function of developmental genes in the context of the biophysics of growth and patterning. VirtualLeaf is an ongoing open-source software project (http://virtualleaf.googlecode.com) that runs on Windows, Mac, and Linux.
Understanding what controls the spatial distribution of fish populations using a multi‐model approach
Authors: PLANQUE BENJAMIN , LOOTS CHRISTOPHE , PETITGAS PIERRE , LINDSTRøM ULF , VAZ SANDRINE 
Published: December 2010

AbstractUnderstanding and predicting the distribution of organisms in heterogeneous environments lies at the heart of ecology. The spatial distribution of fish populations observed in the wild results from the complex interactions of multiple controls both external or internal to the fish populations. Whilst species distribution models (SDMs) have been mostly concerned with static description of species distribution as a function of environmental constraints, models of animal movements (MAMs) have focussed on the dynamic nature of spatial distribution of groups of individuals under a number of constraints external and internal to the population. Besides SDMs and MAMs, modelling the spatial distribution of fish populations can be achieved by models that are fundamentally static (like SDMs) but can also incorporate many hypotheses on the control of fish spatial distribution (like MAMs). The hypotheses underlying these models need to make sense at the population level ‐ rather than at the individual or species level –we term these ‘population distribution models’ (PDMs). PDMs are statistical models that rely on several hypotheses, which include: (i) control through geographical attachment, (ii) environmental conditions, (iii) density‐dependent habitat selection, (iv) spatial dependency, (v) population demographic structure, (vi) species interactions and (vii) population memory. We review the basis behind each of these conceptual models and we examine corresponding numerical applications. We argue that the conceptual models are complementary rather than competing, that existing numerical applications are still rarely compared and combined, and that PDMs can offer a statistical framework to achieve this. We recommend that the numerical models associated with different hypotheses be constructed within such a common general framework. This will permit evaluation, comparison and combination of the multiple hypotheses on fish spatial distribution. It will ultimately lead to a more comprehensive understanding of the factors controlling the spatial distribution of fish populations and to more accurate predictions in which model uncertainty is accounted for.
Understanding what controls the spawning distribution of North Sea whiting (Merlangius merlangus) using a multi‐model approach
Authors: LOOTS CHRISTOPHE , VAZ SANDRINE , PLANQUE BENJAMIN , KOUBBI PHILIPPE 
Published: December 2010

AbstractThe processes that control the spatial distribution of North Sea whiting (Merlangius merlangus) spawning adults are investigated using a statistical multi‐model approach. Models of external and internal controls on the population, such as environmental conditions, spatial constraints, present or past spatial distribution, and demographic state of the population, are evaluated, compared and ranked to select those that are the best able to predict the observed distribution of spawning adults. Model selection is greatly influenced by the selection method, either based on data fitting or prediction, as well as by the threshold value used to stop the selection. Model selection based on prediction tends to select simpler models than selection based on data fitting. The hypotheses underlying the selected models are inferred to play a significant role in controlling North Sea whiting spatial distribution. The multi‐model inference approach developed in this study enables comparison of several theoretical concepts and hypotheses and the results provide important clues on the processes involved in the control of the spatial distribution of whiting. We conclude that whiting has a high spatial fidelity to spawning site which can be linked to either geographical attachment or year‐to‐year persistence of the spatial distribution of the population. Environmental factors – temperature and salinity – appear to influence the geographical extent of spawning whiting distribution, whereas local abundance levels are primarily controlled by internal factors, i.e., population size and spatial segregation between ages.
A matter of timing: the role of ocean conditions in the initiation of spawning migration by late‐run Fraser River sockeye salmon (Oncorhynchus nerka)
Authors: THOMSON RICHARD E. , HOURSTON ROY A. S. 
Published: December 2010

AbstractYear 1995 marked the start of a major shift to earlier river entry of late‐run Fraser River sockeye salmon (Oncorhynchus nerka) en route to the spawning grounds. Earlier entry has typically been accompanied by considerably greater in‐river mortality. We examine this behavioral change using correlation analyses between the entry timing of the Adams River and Weaver Creek stocks and the surface marine conditions encountered by the stocks during their homing migration from the northeast Pacific several months earlier. For Adams stocks, maximum correlation is between entry timing and offshore winds, such that the weaker the wind stress in the direction of the prevailing surface currents in early July, the earlier the river entry in late summer. For Weaver stocks, maximum correlation is with salinity, such that the lower the surface salinity along the coast in August, the earlier the river entry. We hypothesize that oceanic changes lead to changes in late‐run sockeye physiology which then leads to changes in behavior. Physiological changes are postulated to arise from two types of preconditioning: Type‐1 occurs in the offshore region, whereby the weaker the prevailing currents that normally hinder eastward migration, the more endogenous energy available for maturation and the earlier the river entry. Type‐2 occurs in coastal regions, whereby the lower the salinity, the more rapid the osmoregulatory adaptation to freshwater (and possible susceptibility to water‐borne pathogens) and the earlier the entry. Results suggest that the earlier entry that began in the mid‐1990s is linked to weaker ocean currents and lower coastal salinities.
The role of environmental conditions and exploitation in determining dynamics of redfish (Sebastes species) in the Northwest Atlantic
Authors: DEVINE JENNIFER A. , HAEDRICH RICHARD L. 
Published: December 2010

AbstractThe six stocks of redfish (Sebastes spp.) in the Northwest Atlantic have been fished for the past 60 years, during which time they have also experienced considerable variability in environmental conditions. Despite their close proximity and with life‐history features characteristic of many deep‐sea fishes (long‐lived, slow‐growing, late‐maturing, relatively low fecundity), each redfish stock has displayed quite different dynamics. Some have been able to support apparently sustainable fisheries, whereas others have been forced to close. The causes of such differences are unclear. We used dynamic factor analysis to determine the relative impacts of exploitation (days fishing for redfish, days fishing for shrimp, days fished by all fisheries, catch in the redfish fishery, total redfish catch) and environment (North Atlantic Oscillation, surface temperature, salinity, shallow, middle, and deep bottom temperatures) on trends of abundance in each stock over the years 1960–2004. The results showed that a mix of exploitation and environmental variability, with various and different lag times, accounted for observed trends. The Gulf of St. Lawrence stock was affected most by exploitation. Flemish Cap and northern Newfoundland‐Labrador stocks were mostly affected by environmental factors with longer time lags than more southerly stocks. We conclude that management of redfish must take into account individual responses to exploitation and environment over the time periods during which such factors operate, often decades or more, as opposed to the usual practice of reviewing only dynamics of the past few years. Deep‐sea populations cannot be managed on the same scales as shelf fisheries.