145 research outputs found
Foraging Distance of the Argentine Ant in California Vineyards.
Argentine ants, Linepithema humile (Mayr) (Hymenoptera: Formicidae), form mutualisms with hemipteran pests in crop systems. In vineyards, they feed on honeydew produced by mealybugs and soft scales, which they tend and protect from natural enemies. Few options for controlling Argentine ants are available; one of the more effective approaches is to use liquid baits containing a low dose of an insecticide. Knowledge of ant foraging patterns is required to estimate how many bait stations to deploy per unit area. To measure how far ants move liquid bait in vineyards, we placed bait stations containing sugar water and a protein marker in plots for 6 d, and then collected ants along transects extending away from bait stations. The ants moved an average of 16.08 m and 12.21 m from bait stations in the first and second years of the study, respectively. Marked ants were found up to 63 m from bait stations; however, proportions of marked ants decreased exponentially as distance from the bait station increased. Results indicate that Argentine ants generally forage at distancesvineyards, thus suggesting that insecticide bait stations must be deployed at intervals of 36 m or less to control ants. We found no effect of insecticide on distances that ants moved the liquid bait, but this may have been because bait station densities were too low to affect the high numbers of Argentine ants that were present at the study sites
Potential host ranges of three Asian larval parasitoids of Drosophila suzukii
AbstractAsobara japonica (Hymenoptera: Braconidae), Ganaspis brasiliensis and Leptopilina japonica (Hymenoptera: Figitidae) are Asian larval parasitoids of spotted wing drosophila, Drosophila suzukii (Diptera: Drosophilidae). This study evaluated these parasitoids' capacity to attack and develop from 24 non-target drosophilid species. Results showed that all three parasitoids were able to parasitize host larvae of multiple non-target species in artificial diet; A. japonica developed from 19 tested host species, regardless of the phylogenetic position of the host species, L. japonica developed from 11 tested species; and G. brasiliensis developed from only four of the exposed species. Success rate of parasitism (i.e., the probability that an adult wasp successfully emerged from a parasitized host) by the two figitid parasitoids was low in hosts other than the three species in the melanogaster group (D. melanogaster, D. simulans, and D. suzukii). The failure of the figitids to develop in most of the tested host species appears to correspond with more frequent encapsulation of the parasitoids by the hosts. The results indicate that G. brasiliensis is the most host specific to D. suzukii, L. japonica attacks mainly species in the melanogaster group and A. japonica is a generalist, at least physiologically. Overall, the developmental time of the parasitoids increased with the host's developmental time. The body size of female A. japonica (as a model species) was positively related to host size, and mature egg load of female wasps increased with female body size. We discuss the use of these parasitoids for classical biological control of D. suzukii
Absence of Evidence Is Not Evidence of Absence: The Color-Density Relation at Fixed Stellar Mass Persists to z ~ 1
We use data drawn from the DEEP2 Galaxy Redshift Survey to investigate the
relationship between local galaxy density, stellar mass, and rest-frame galaxy
color. At z ~ 0.9, we find that the shape of the stellar mass function at the
high-mass (log (M*/Msun) > 10.1) end depends on the local environment, with
high-density regions favoring more massive systems. Accounting for this stellar
mass-environment relation (i.e., working at fixed stellar mass), we find a
significant color-density relation for galaxies with 10.6 < log(M*/Msun) < 11.1
and 0.75 < z < 0.95. This result is shown to be robust to variations in the
sample selection and to extend to even lower masses (down to log(M*/Msun) ~
10.4). We conclude by discussing our results in comparison to recent works in
the literature, which report no significant correlation between galaxy
properties and environment at fixed stellar mass for the same redshift and
stellar mass domain. The non-detection of environmental dependence found in
other data sets is largely attributable to their smaller samples size and lower
sampling density, as well as systematic effects such as inaccurate redshifts
and biased analysis techniques. Ultimately, our results based on DEEP2 data
illustrate that the evolutionary state of a galaxy at z ~ 1 is not exclusively
determined by the stellar mass of the galaxy. Instead, we show that local
environment appears to play a distinct role in the transformation of galaxy
properties at z > 1.Comment: 10 pages, 5 Figures; Accepted for publication in MNRA
The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts
We describe the design and data sample from the DEEP2 Galaxy Redshift Survey,
the densest and largest precision-redshift survey of galaxies at z ~ 1
completed to date. The survey has conducted a comprehensive census of massive
galaxies, their properties, environments, and large-scale structure down to
absolute magnitude M_B = -20 at z ~ 1 via ~90 nights of observation on the
DEIMOS spectrograph at Keck Observatory. DEEP2 covers an area of 2.8 deg^2
divided into four separate fields, observed to a limiting apparent magnitude of
R_AB=24.1. Objects with z < 0.7 are rejected based on BRI photometry in three
of the four DEEP2 fields, allowing galaxies with z > 0.7 to be targeted ~2.5
times more efficiently than in a purely magnitude-limited sample. Approximately
sixty percent of eligible targets are chosen for spectroscopy, yielding nearly
53,000 spectra and more than 38,000 reliable redshift measurements. Most of the
targets which fail to yield secure redshifts are blue objects that lie beyond z
~ 1.45. The DEIMOS 1200-line/mm grating used for the survey delivers high
spectral resolution (R~6000), accurate and secure redshifts, and unique
internal kinematic information. Extensive ancillary data are available in the
DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into
one of the richest multiwavelength regions on the sky. DEEP2 surpasses other
deep precision-redshift surveys at z ~ 1 in terms of galaxy numbers, redshift
accuracy, sample number density, and amount of spectral information. We also
provide an overview of the scientific highlights of the DEEP2 survey thus far.
This paper is intended as a handbook for users of the DEEP2 Data Release 4,
which includes all DEEP2 spectra and redshifts, as well as for the
publicly-available DEEP2 DEIMOS data reduction pipelines. [Abridged]Comment: submitted to ApJS; data products available for download at
http://deep.berkeley.edu/DR4
The Sloan Digital Sky Survey Quasar Catalog IV. Fifth Data Release
We present the fourth edition of the Sloan Digital Sky Survey (SDSS) Quasar
Catalog. The catalog contains 77,429 objects; this is an increase of over
30,000 entries since the previous edition. The catalog consists of the objects
in the SDSS Fifth Data Release that have luminosities larger than M_i = -22.0
(in a cosmology with H_0 = 70 km/s/Mpc, Omega_M = 0.3, and Omega_Lambda = 0.7)
have at least one emission line with FWHM larger than 1000 km/s, or have
interesting/complex absorption features, are fainter than i=15.0, and have
highly reliable redshifts. The area covered by the catalog is 5740 sq. deg. The
quasar redshifts range from 0.08 to 5.41, with a median value of 1.48; the
catalog includes 891 quasars at redshifts greater than four, of which 36 are at
redshifts greater than five. Approximately half of the catalog quasars have i <
19; nearly all have i < 21. For each object the catalog presents positions
accurate to better than 0.2 arcsec. rms per coordinate, five-band (ugriz)
CCD-based photometry with typical accuracy of 0.03 mag, and information on the
morphology and selection method. The catalog also contains basic radio,
near-infrared, and X-ray emission properties of the quasars, when available,
from other large-area surveys. The calibrated digital spectra cover the
wavelength region 3800--9200A at a spectral resolution of ~2000. The spectra
can be retrieved from the public database using the information provided in the
catalog. The average SDSS colors of quasars as a function of redshift, derived
from the catalog entries, are presented in tabular form. Approximately 96% of
the objects in the catalog were discovered by the SDSS.Comment: 37 pages, Accepted for publication in A
The Metallicity Distribution Functions of SEGUE G and K dwarfs: Constraints for Disk Chemical Evolution and Formation
We present the metallicity distribution function (MDF) for 24,270 G and
16,847 K dwarfs at distances from 0.2 to 2.3 kpc from the Galactic plane, based
on spectroscopy from the Sloan Extension for Galactic Understanding and
Exploration (SEGUE) survey. This stellar sample is significantly larger in both
number and volume than previous spectroscopic analyses, which were limited to
the solar vicinity, making it ideal for comparison with local volume-limited
samples and Galactic models. For the first time, we have corrected the MDF for
the various observational biases introduced by the SEGUE target selection
strategy. The SEGUE sample is particularly notable for K dwarfs, which are too
faint to examine spectroscopically far from the solar neighborhood. The MDF of
both spectral types becomes more metal-poor with increasing |Z|, which reflects
the transition from a sample with small [alpha/Fe] values at small heights to
one with enhanced [alpha/Fe] above 1 kpc. Comparison of our SEGUE distributions
to those of two different Milky Way models reveals that both are more
metal-rich than our observed distributions at all heights above the plane. Our
unbiased observations of G and K dwarfs provide valuable constraints over the
|Z|-height range of the Milky Way disk for chemical and dynamical Galaxy
evolution models, previously only calibrated to the solar neighborhood, with
particular utility for thin- and thick-disk formation models.Comment: 70 pages, 25 figures, 7 tables. Accepted by The Astrophysical Journa
The Sloan Digital Sky Survey Quasar Catalog I. Early Data Release
We present the first edition of the Sloan Digital Sky Survey (SDSS) Quasar
Catalog. The catalog consists of the 3814 objects (3000 discovered by the SDSS)
in the initial SDSS public data release that have at least one emission line
with a full width at half maximum larger than 1000 km/s, luminosities brighter
than M_i^* = -23, and highly reliable redshifts. The area covered by the
catalog is 494 square degrees; the majority of the objects were found in SDSS
commissioning data using a multicolor selection technique. The quasar redshifts
range from 0.15 to 5.03. For each object the catalog presents positions
accurate to better than 0.2" rms per coordinate, five band (ugriz) CCD-based
photometry with typical accuracy of 0.05 mag, radio and X-ray emission
properties, and information on the morphology and selection method. Calibrated
spectra of all objects in the catalog, covering the wavelength region 3800 to
9200 Angstroms at a spectral resolution of 1800-2100, are also available. Since
the quasars were selected during the commissioning period, a time when the
quasar selection algorithm was undergoing frequent revisions, the sample is not
homogeneous and is not intended for statistical analysis.Comment: 27 pages, 4 figures, 4 tables, accepted by A
Redating the earliest evidence of the mid-Holocene relative sea-level highstand in Australia and implications for global sea-level rise.
Reconstructing past sea levels can help constrain uncertainties surrounding the rate of change, magnitude, and impacts of the projected increase through the 21st century. Of significance is the mid-Holocene relative sea-level highstand in tectonically stable and remote (far-field) locations from major ice sheets. The east coast of Australia provides an excellent arena in which to investigate changes in relative sea level during the Holocene. Considerable debate surrounds both the peak level and timing of the east coast highstand. The southeast Australian site of Bulli Beach provides the earliest evidence for the establishment of a highstand in the Southern Hemisphere, although questions have been raised about the pretreatment and type of material that was radiocarbon dated for the development of the regional sea-level curve. Here we undertake a detailed morpho- and chronostratigraphic study at Bulli Beach to better constrain the timing of the Holocene highstand in eastern Australia. In contrast to wood and charcoal samples that may provide anomalously old ages, probably due to inbuilt age, we find that short-lived terrestrial plant macrofossils provide a robust chronological framework. Bayesian modelling of the ages provide improved dating of the earliest evidence for a highstand at 6,880±50 cal BP, approximately a millennium later than previously reported. Our results from Bulli now closely align with other sea-level reconstructions along the east coast of Australia, and provide evidence for a synchronous relative sea-level highstand that extends from the Gulf of Carpentaria to Tasmania. Our refined age appears to be coincident with major ice mass loss from Northern Hemisphere and Antarctic ice sheets, supporting previous studies that suggest these may have played a role in the relative sea-level highstand. Further work is now needed to investigate the environmental impacts of regional sea levels, and refine the timing of the subsequent sea-level fall in the Holocene and its influence on coastal evolution
The Sloan Digital Sky Survey Quasar Catalog V. Seventh Data Release
We present the fifth edition of the Sloan Digital Sky Survey (SDSS) Quasar
Catalog, which is based upon the SDSS Seventh Data Release. The catalog, which
contains 105,783 spectroscopically confirmed quasars, represents the conclusion
of the SDSS-I and SDSS-II quasar survey. The catalog consists of the SDSS
objects that have luminosities larger than M_i = -22.0 (in a cosmology with H_0
= 70 km/s/Mpc Omega_M = 0.3, and Omega_Lambda = 0.7) have at least one emission
line with FWHM larger than 1000 km/s or have interesting/complex absorption
features, are fainter than i > 15.0 and have highly reliable redshifts. The
catalog covers an area of 9380 deg^2. The quasar redshifts range from 0.065 to
5.46, with a median value of 1.49; the catalog includes 1248 quasars at
redshifts greater than four, of which 56 are at redshifts greater than five.
The catalog contains 9210 quasars with i < 18; slightly over half of the
entries have i< 19. For each object the catalog presents positions accurate to
better than 0.1" rms per coordinate, five-band (ugriz) CCD-based photometry
with typical accuracy of 0.03 mag, and information on the morphology and
selection method. The catalog also contains radio, near-infrared, and X-ray
emission properties of the quasars, when available, from other large-area
surveys. The calibrated digital spectra cover the wavelength region 3800-9200
Ang. at a spectral resolution R = 2000 the spectra can be retrieved from the
SDSS public database using the information provided in the catalog. Over 96% of
the objects in the catalog were discovered by the SDSS. We also include a
supplemental list of an additional 207 quasars with SDSS spectra whose archive
photometric information is incomplete.Comment: Accepted, to appear in AJ, 7 figures, electronic version of Table 2
is available, see
http://www.sdss.org/dr7/products/value_added/qsocat_dr7.htm
Cosmological parameters from SDSS and WMAP
We measure cosmological parameters using the three-dimensional power spectrum
P(k) from over 200,000 galaxies in the Sloan Digital Sky Survey (SDSS) in
combination with WMAP and other data. Our results are consistent with a
``vanilla'' flat adiabatic Lambda-CDM model without tilt (n=1), running tilt,
tensor modes or massive neutrinos. Adding SDSS information more than halves the
WMAP-only error bars on some parameters, tightening 1 sigma constraints on the
Hubble parameter from h~0.74+0.18-0.07 to h~0.70+0.04-0.03, on the matter
density from Omega_m~0.25+/-0.10 to Omega_m~0.30+/-0.04 (1 sigma) and on
neutrino masses from <11 eV to <0.6 eV (95%). SDSS helps even more when
dropping prior assumptions about curvature, neutrinos, tensor modes and the
equation of state. Our results are in substantial agreement with the joint
analysis of WMAP and the 2dF Galaxy Redshift Survey, which is an impressive
consistency check with independent redshift survey data and analysis
techniques. In this paper, we place particular emphasis on clarifying the
physical origin of the constraints, i.e., what we do and do not know when using
different data sets and prior assumptions. For instance, dropping the
assumption that space is perfectly flat, the WMAP-only constraint on the
measured age of the Universe tightens from t0~16.3+2.3-1.8 Gyr to
t0~14.1+1.0-0.9 Gyr by adding SDSS and SN Ia data. Including tensors, running
tilt, neutrino mass and equation of state in the list of free parameters, many
constraints are still quite weak, but future cosmological measurements from
SDSS and other sources should allow these to be substantially tightened.Comment: Minor revisions to match accepted PRD version. SDSS data and ppt
figures available at http://www.hep.upenn.edu/~max/sdsspars.htm
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