440 research outputs found
Pathogen avoidance by insect predators
Insects can detect cues related to the risk of attack by their natural enemies. Pathogens are among the natural enemies of insects and entomopathogenic fungi attack a wide array of host species. Evidence documents that social insects in particular have adapted behavioural mechanisms to avoid infection by fungal pathogens. These mechanisms are referred to as 'behavioural resistance'. However, there is little evidence for similar adaptations in non-social insects.
We have conducted experiments to assess the potential of common insect predators to detect and avoid their entomopathogenic fungal natural enemy Beauveria bassiana. The predatory bug Anthocoris nemorum was able to detect and avoid nettle leaves that were treated with B. bassiana. Females laid fewer eggs on leaf halves contaminated with the pathogen. Similarly, females were very reluctant to contact nettle leaves contaminated with the fungus compared to uncontaminated control leaves in âno-choiceâ experiments.
Adult seven spot ladybirds, Coccinella septempunctata, overwinter in the litter layer often in groups. Adult C. septempunctata modified their overwintering behaviour in relation to the presence of B. bassiana conidia in soil and sporulating conspecifics by moving away from sources of infection. Furthermore active (non-overwintering) adult C. septempunctata were also able to detect and avoid B. bassiana conidia on different substrates; bean leaves, soil and sporulating on dead conspecifics.
Our studies show that insect predators have evolved mechanisms to detect and avoid pathogens that they are susceptible to. Fungal pathogens may be significant mortality factors among populations of insect predators, especially long-lived species that must diapause before reproduction. Likewise, actively foraging species are more likely to come in contact with pathogens than predators that sit and wait for prey. These particular groups of insects will benefit from adaptations to avoid pathogens
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A new regime of carbon counting: the practices and politics of accounting for everyday carbon through C02e
Inspired by the commercial desires of global brands and retailers to access the lucrative green consumer market, carbon is increasingly being counted and made knowable at the mundane sites of everyday production and consumption, from the carbon footprint of a plastic kitchen fork to that of an online bank account. Despite the challenges of counting and making commensurable the global warming impact of a myriad of biophysical and societal activities, this desire to communicate a product or service's carbon footprint has sparked complicated carbon calculative practices and enrolled actors at literally every node of multi-scaled and vastly complex global supply chains. Against this landscape, this paper critically analyzes the counting practices that create the âeâ in âCO2eâ. It is shown that, central to these practices are a series of tools, models and databases which, in building upon previous work (Eden, 2012 and Star and Griesemer, 1989) we conceptualize here as âboundary objectsâ. By enrolling everyday actors from farmers to consumers, these objects abstract and stabilize greenhouse gas emissions from their messy material and social contexts into units of CO2e which can then be translated along a product's supply chain, thereby establishing a new currency of âeveryday supply chain carbonâ. However, in making all greenhouse gas-related practices commensurable and in enrolling and stabilizing the transfer of information between multiple actors these objects oversee a process of simplification reliant upon, and subject to, a multiplicity of approximations, assumptions, errors, discrepancies and/or omissions. Further the outcomes of these tools are subject to the politicized and commercial agendas of the worlds they attempt to link, with each boundary actor inscribing different meanings to a product's carbon footprint in accordance with their specific subjectivities, commercial desires and epistemic framings. It is therefore shown that how a boundary object transforms greenhouse gas emissions into units of CO2e, is the outcome of distinct ideologies regarding âwhatâ a product's carbon footprint is and how it should be made legible. These politicized decisions, in turn, inform specific reduction activities and ultimately advance distinct, specific and increasingly durable transition pathways to a low carbon society
Effect of Nucleon Structure Variation in Super-allowed Fermi Beta-decay
There is a well known anomaly between the value of the Fermi decay constant
extracted from super-allowed Fermi beta-decay of nuclear isotriplets and that
required by unitarity of the Cabibbo-Kobayashi-Maskawa matrix. This discrepancy
remains at the level of a few tenths of a percent after the most rigorous
investigation of conventional nuclear and radiative corrections. Within the
framework of the quark-meson coupling model of nuclear matter, which has been
previously applied successfully to phenomena such as nuclear saturation and
nuclear charge symmetry violation, we show that it is possible to understand a
significant fraction of the observed anomaly.Comment: 11 pages with 1 figure and 1 tabl
Red and White Blood Cell Counts Are Associated With Bone Marrow Adipose Tissue, Bone Mineral Density, and Bone Microarchitecture in Premenopausal Women
Bone marrow adipose tissue (BMAT) resides within the bone marrow microenvironment where its function remains poorly understood. BMAT is elevated in anorexia nervosa, a disease model of chronic starvation, despite depletion of other fat depots. In addition to BMAT, the marrow microenvironment also consists of osteoblast and hematopoietic progenitors. BMAT is inversely associated with bone mineral density (BMD) in multiple populations including women with anorexia nervosa, and regulates hematopoiesis in animal models. We hypothesized that BMAT would be associated with circulating populations of hematopoietic cells (red and white blood cells) in humans and performed a post hoc analysis of two studiesâa crossâsectional study and a longitudinal studyâto investigate this hypothesis. We studied 89 premenopausal women crossâsectionally (median age [interquartile range], 27 [24.5, 31.7] years), including 35 with anorexia nervosa. We investigated associations between red blood cell (RBC) and white blood cell (WBC) counts and BMAT assessed by 1Hâmagnetic resonance spectroscopy, BMD assessed by DXA, and bone microarchitecture assessed by HRâpQCT. In addition, we analyzed longitudinal data in six premenopausal women with anorexia nervosa treated with transdermal estrogen for 6âmonths and measured changes in BMAT and blood cell counts during treatment. Crossâsectionally, BMAT was inversely associated with WBC and RBC counts. In contrast, BMD and parameters of bone microarchitecture were positively associated with WBC and RBC. In women with anorexia nervosa treated with transdermal estrogen for 6âmonths, decreases in BMAT were significantly associated with increases in both RBC and hematocrit (rho = â0.83, p = 0.04 for both). In conclusion, we show that BMAT is inversely associated with WBC and RBC in premenopausal women, and there is a potential association between longitudinal changes in BMAT and changes in RBC. These associations warrant further study and may provide further insight into the role and function of this understudied adipose depot. © 2020 American Society for Bone and Mineral Research.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155991/1/jbmr3986.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155991/2/jbmr3986_am.pd
Report on concentrations, lifetimes, and trends of CFCs, halons, and related species
The atmospheric lifetimes of molecules containing chlorine and bromine are the dominant parameters influencing their ability to promote enhanced ozone destruction in the stratosphere. The purpose of this report is to assess the present state of knowledge of the lifetimes of halocarbons using two complementary approaches. First, a time series of measurements of gas concentrations is used together with information on their emissions histories and a computational model of atmospheric circulation and chemistry to infer lifetimes through a mass balance approach. Second, an atmospheric chemical-dynamical model is used with detailed information on the chemistry and spectroscopy of the molecules of interest to calculate lifetimes. The lifetimes determined by these two methods are then compared. Attention is focused most closely on fully halogenated chlorine- and bromine-containing molecules, primarily the chlorofluorocarbons, and the halons, because of their ability to deliver chlorine and bromine to the stratosphere. Some attention will be given to those molecules containing hydrogen, which are subject to removal in the troposphere primarily by reaction with OH and by other processes
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