2,926 research outputs found
Root Weevil (Coleoptera: Curculionidae) and Ground Beetle (Coleoptera: Carabidae) Immigration into Strawberry Plots Protected by Fence or Portable Trench Barriers
Physical exclusion shows some potential as a novel root weevil control strategy, but barriers to root weevil immigration may also exclude beneficial insects, such as ground beetles. A field study was undertaken in 1997 to assess the impact of two physical barriers—portable plastic trenches and aluminum fences with Teflon tape—on root weevil and ground beetle immigration into plots of strawberry, Fragaria x ananassa (Duchesne). Barypeithes pellucidus (Boheman) and Nemocestes incomptus (Horn), each comprised 43% of the root weevils caught at the site. Most (86%) of the ground beetles caught in control plots were longer than 1 cm, the width of the gap in the portable trench top. Trenches excluded 75 and 63% of B. pellucidus and N. incomptus, respectively, without significantly reducing immigration of large (<1 cm) ground beetles. Fences excluded 65, 84, and 99% of B. pellucidus, N. incomptus, and large ground beetles, respectively. Adding diatomaceous earth to trenches did not increase their efficacy, and fences without Teflon tape excluded ground beetles but not root weevils. The reduction in the population of root weevils and other strawberry pests caused by the use of barriers reduced damage to strawberry plant leaves and increased strawberry plant survival relative to unprotected control plots. Advantages and disadvantages of these physical control tools are discussed with a view to creating superior tools for root weevil exclusion, compatible with an integrated pest management approach. Portable trenches may offer a means of selectively excluding root weevils but not ground beetles
Moisture tempers impairment of adult Otiorhynchus sulcatus (Coleoptera: Curculionidae) climbing ability by fluoropolymer, talc dust, and lithium grease
As part of a project to develop tools for the physical exclusion of flightless root weevils, adult black vine weevils (BVW), Otiorhynchus sulcatus (F.), were placed in open enclosures with smooth walls of glass, plastic or aluminum to test their ability to escape by climbing. Enclosure walls were left untreated or were treated with substances known to reduce insect climbing ability: fluoropolymer, powdered talc and lithium grease. No BVW escapes were observed under dry conditions, but all treatments allowed some escapes under wet conditions, suggesting that moisture helps BVW adults scale treated surfaces. The results help explain the ability of root weevils to overcome physical barriers under field conditions
Importance of Collection Overhangs on the Efficacy of Exclusion Fences for Managing Cabbage Flies (Diptera: Anthomyiidae)
Fine nylon mesh fences (135 cm high) with varying lengths of downward-sloping collection overhangs were evaluated for efficacy in excluding the female cabbage flies Delia radicum (L.) from plots of radish, Raphanus sativus (L.). During three trials conducted in 1994 and 1995, fences without overhangs, fences with 12.5-cm overhangs, or fences with 50-cm overhangs were tested against fences with standard 25-cm overhangs and unfenced control plots. In fenced plots with standard 25-cm overhangs, the mean number of D. radicum females caught on yellow sticky traps placed within plots was 85% less than those caught in corresponding control plots. The mean numbers of D. radicum females caught in fenced enclosures with no overhangs, 12.5-cm overhangs, or 50-cm overhangs, were 61, 67, and 94% less than those caught in corresponding control plots, respectively. The mean proportion of radishes damaged by D. radicum larvae inside enclosures with 25-cm overhangs was 62% less than in corresponding control plots. The mean proportions of radishes damaged inside fences with no overhangs, 12.5-cm overhangs, or 50-cm overhangs were 33, 59, and 81% less than those caught in corresponding control plots, respectively. Results are discussed in terms of defining an appropriate fence design for commercial use
Generalized focus point and mass spectra comparison of highly natural SUGRA GUT models
Supergravity grand unified models (SUGRA GUTs) are highly motivated and allow
for a high degree of electroweak naturalness when the superpotential parameter
mu~ 100-300 GeV (preferring values closer to 100 GeV). We first illustrate that
models with radiatively-driven naturalness enjoy a generalized focus-point
behavior wherein all soft terms are correlated instead of just scalar masses.
Next, we generate spectra from four SUGRA GUT archetypes: 1. SO(10) models
where the Higgs doublets live in different 10-dimensional irreducible
representations (irreps), 2. models based on SO(10) where the Higgs multiplets
live in a single 10-dimensional irrep but with D-term scalar mass splitting, 3.
models based on SU(5) and 4. a more general SUGRA model with 12 independent
parameters. Electroweak naturalness implies for all models a spectrum of light
higgsinos with m(higgsinos)< 300 GeV and gluinos with m(gluino)< 2-4 TeV.
However, masses and mixing in the third generation sfermion sector differ
distinctly between the models. These latter differences would be most easily
tested at a linear e^+e^- collider with \sqrt{s}~ multi-TeV-scale but
measurements at a 50-100 TeV hadron collider are also possible.Comment: 28 pages with 38 .png frames; some references added for version
Supergravity gauge theories strike back: There is no crisis for SUSY but a new collider may be required for discovery
More than 30 years ago, Arnowitt-Chamseddine-Nath (ACN) and others
established the compelling framework of supergravity gauge theories (SUGRA) as
a picture for the next step in beyond the Standard Model physics. We review the
current SUGRA scenario in light of recent data from LHC8 collider searches and
the Higgs boson discovery. While many SUSY and non-SUSY scenarios are highly
disfavored or even excluded by LHC, the essential SUGRA scenario remains intact
and as compelling as ever. For naturalness, some non-universality between
matter and Higgs sector soft terms is required along with substantial trilinear
soft terms. SUSY models with radiatively-driven naturalness (RNS) are found
with high scale fine-tuning at a modest ~10%. In this case, natural SUSY might
be discovered at LHC13 but could also easily elude sparticle search endeavors.
A linear e^+e^- collider with \sqrt{s}>2m(higgsino) is needed to provide the
definitive search for the required light higgsino states which are the hallmark
of natural SUSY. In the most conservative scenario, we advocate inclusion of a
Peccei-Quinn sector so that dark matter is composed of a WIMP/axion admixture
i.e. two dark matter particles.Comment: Contribution to The Proceedings of the Richard Arnowitt Memorial
Symposium; 18 pages with 17 figures; revised version includes 3 added figures
and some typo corrections; v3 includes some added references and one updated
figur
Superparticle phenomenology from the natural mini-landscape
The methodology of the heterotic mini-landscape attempts to zero in on
phenomenologically viable corners of the string landscape where the effective
low energy theory is the Minimal Supersymmetric Standard Model with localized
grand unification. The gaugino mass pattern is that of mirage-mediation. The
magnitudes of various SM Yukawa couplings point to a picture where scalar soft
SUSY breaking terms are related to the geography of fields in the compactified
dimensions. Higgs fields and third generation scalars extend to the bulk and
occur in split multiplets with TeV scale soft masses. First and second
generation scalars, localized at orbifold fixed points or tori with enhanced
symmetry, occur in complete GUT multiplets and have much larger masses. This
picture can be matched onto the parameter space of generalized mirage
mediation. Naturalness considerations, the requirement of the observed
electroweak symmetry breaking pattern, and LHC bounds on m(gluino) together
limit the gravitino mass to the m_{3/2}~ 5-60 TeV range. The mirage unification
scale is bounded from below with the limit depending on the ratio of squark to
gravitino masses. We show that while natural SUSY in this realization may
escape detection even at the high luminosity LHC, the high energy LHC with
\sqrt{s}=33 TeV could unequivocally confirm or exclude this scenario. It should
be possible to detect the expected light higgsinos at the ILC if these are
kinematically accessible, and possibly also discriminate the expected
compression of gaugino masses in the natural mini-landscape picture from the
mass pattern expected in models with gaugino mass unification. The thermal WIMP
signal should be accessible via direct detection searches at the multi-ton
noble liquid detectors such as Xenon-nT or LZ.Comment: 33 pages with 32 .png figure
A COMPARISON OF MULTIFACTOR PRODUCTIVITY CALCULATIONS OF THE U.S. AGRICULTURAL SECTOR
Productivity Analysis,
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