6,736 research outputs found

    Use of Spotted Knapweed/Star Thistle (Asterales: Asteraceae) as the Primary Source of Nectar by Early Migrating Monarch Butterflies (Lepidoptera: Nymphalidae) from Beaver Island, Michigan

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    Recent observations over the past decade suggest that the invasive star thistle (aka spotted knapweed (Centaurea stoebe L.) provides much of the nectar that supports monarch butterflies (Danaus plexippus) in their pre-migratory and early migratory flight from the Beaver Island archipelago, an isolated chain of islands located in northern Lake Michigan. With the advent and continuation of global climate change, the opportunistic evolutionary changes that may take place between migrating monarchs and their dependence on non-native nectariferous plants, prior to migration, is worth further documentation and examination

    Measuring the Effects of ā€œOpportunistic Defenseā€ of the Bracken Fern, \u3ci\u3e(Pteridium Aquilinum)\u3c/i\u3e by Patrolling Ants (Hymenoptera: Formicidae) at Pierce Cedar Creek Institute in South Central Michigan

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    In this study we show that in South Central Michigan (Pierce Cedar Creek Institute) eight ant species patrol bracken fern (Pteridium aquilinum) during the sensitive crozier growth stage. At times these ants remove herbivorous insects from rapidly expanding fronds. A new method for analyzing herbivory of bracken fern is employed to measure chewing damage to the fronds. Our results show that ants do in fact remove some herbivores from bracken fronds during the crozier stage; however, statistical analyses comparing the amount of chewing damage between treated and untreated fronds at the end of the growing season show no statistical difference

    Spiraling Flight Behavior May Integrate the Biological Compass Systems of Migratory North American Monarch Butterflies, (Danaus plexippus, L.)

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    Here I report a unique spiraling flight and orientation behavior (comprising multiple clockwise and counterclockwise circles coupled by extended figure-8 patterns) observed in free-flying ā€œlateā€ migratory monarchs released under sunny ambient field conditions from a location with an unobstructed view of the sky. Following this spiraling flight, migrants continue to fly at very high altitudes until a final orientation and migratory flight direction is established with vanishing bearings statistically concentrated to the SW/W. These results provide preliminary evidence for the possible calibration and use of an inclination magnetic compass that can be used under all local free-flying field conditions. During this spiraling flight, migrating monarch butterflies are proposed to be measuring the direction and inclination of the continuously varying local magnetic field, in a manner analogous to the figure-8 pattern performed to calibrate digital compasses. This behavioral research focuses on the vital pre-migratory orientation and flight behavior that may provide a key behavioral link explaining how migrating monarch butterflies using a time-compensated sun compass system could also integrate the biophysical input from the polarized UV sensitive dorsal rim area (DRA) and the cellular cryptochrome (CRY) system linked to the proposed inclination-based magnetic compass system residing in the distal end of the antennae

    Use of Spotted Knapweed/Star Thistle (Asterales: Asteraceae) as the Primary Source of Nectar by Early Migrating Monarch Butterflies (Lepidoptera: Nymphalidae) from Beaver Island, Michigan

    Get PDF
    Recent observations over the past decade suggest that the invasive star thistle (aka spotted knapweed (Centaurea stoebe L.) provides much of the nectar that supports monarch butterflies (Danaus plexippus) in their pre-migratory and early migratory flight from the Beaver Island archipelago, an isolated chain of islands located in northern Lake Michigan. With the advent and continuation of global climate change, the opportunistic evolutionary changes that may take place between migrating monarchs and their dependence on non-native nectariferous plants, prior to migration, is worth further documentation and examination

    Driver vs. manager perceptions of commonly used safety practices in commercial motor vehicle operations

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    This research investigated the perceptions of Commercial Motor Vehicle Operators and Safety Professionals regarding 35 commonly implemented practices used to improve operating safety. Several differences were found in how drivers of different backgrounds rated various practices, and between the drivers and safety managers. These differences were found to be persistent even when combined with measures of safety performance and experience. Managers tended to overvalue (relative to drivers) practices related to hiring, while drivers tended to overvalue (relative to managers) practices related to company support and reward systems. Motor Carriers, insurers, and regulators could consider areas of agreement with respect to high value practices as actionable for increased investment of resources. At the same time, resources allocated toward areas of low perceived value could be reduced

    Measuring the Effects of ā€œOpportunistic Defenseā€ of the Bracken Fern, \u3ci\u3e(Pteridium Aquilinum)\u3c/i\u3e by Patrolling Ants (Hymenoptera: Formicidae) at Pierce Cedar Creek Institute in South Central Michigan

    Get PDF
    In this study we show that in South Central Michigan (Pierce Cedar Creek Institute) eight ant species patrol bracken fern (Pteridium aquilinum) during the sensitive crozier growth stage. At times these ants remove herbivorous insects from rapidly expanding fronds. A new method for analyzing herbivory of bracken fern is employed to measure chewing damage to the fronds. Our results show that ants do in fact remove some herbivores from bracken fronds during the crozier stage; however, statistical analyses comparing the amount of chewing damage between treated and untreated fronds at the end of the growing season show no statistical difference

    Safety attitudes and behavioral intentions of municipal waste disposal drivers

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    The Theory of Planned Behavior was used to study factors useful for predicting Behavioral Intentions to commit unsafe acts while driving for commercial drivers working for municipal waste management operations centers. The Theory of Planned Behavior was found to be moderately effective in predicting behavioral intentions, particularly through the constructs of Attitude and Perceived Control. Driver perceptions of safety climate, self-assessed personal safety performance, risk aversion, and attitudes toward behavioral factors associated with engaging in risky behaviors while operating motor vehicles were studied. Risk aversion and driver perception of their own safety performance were also useful predictors of intention

    The Sensitivity of the IceCube Neutrino Detector to Dark Matter Annihilating in Dwarf Galaxies

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    In this paper, we compare the relative sensitivities of gamma-ray and neutrino observations to the dark matter annihilation cross section in leptophilic models such as have been designed to explain PAMELA data. We investigate whether the high energy neutrino telescope IceCube will be competitive with current and upcoming searches by gamma-ray telescopes, such as the Atmospheric Cerenkov Telescopes (ACTs) (HESS, VERITAS and MAGIC), or the Fermi Gamma Ray Space Telescope, in detecting or constraining dark matter particles annihilating in dwarf spheroidal galaxies. We find that after ten years of observation of the most promising nearby dwarfs, IceCube will have sensitivity comparable to the current sensitivity of gamma-ray telescopes only for very heavy (m_X > 7 TeV) or relatively light (m_X < 200 GeV) dark matter particles which annihilate primarily to mu+mu-. If dark matter particles annihilate primarily to tau+tau-, IceCube will have superior sensitivity only for dark matter particle masses below the 200 GeV threshold of current ACTs. If dark matter annihilations proceed directly to neutrino-antineutrino pairs a substantial fraction of the time, IceCube will be competitive with gamma-ray telescopes for a much wider range of dark matter masses.Comment: 7 pages, 3 figures. v2: references added and minor revisions. v3: as published in PRD
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