Temporal Dynamics of Iris Yellow Spot Virus and Its Vector, Thrips tabaci (Thysanoptera: Thripidae), in Seeded and Transplanted Onion Fields

Onion thrips, Thrips tabaci (Lindeman) (Thysanoptera: Thripidae), can reduce onion bulb yield and transmit iris yellow spot virus (IYSV) (Bunyaviridae: Tospovirus), which can cause additional yield losses. In New York, onions are planted using seeds and imported transplants. IYSV is not seed transmitted, but infected transplants have been found in other U.S. states. Transplants are also larger than seeded onions early in the season, and thrips, some of which may be viruliferous, may preferentially colonize larger plants. Limited information is available on the temporal dynamics of IYSV and its vector in onion fields. In 2007 and 2008, T. tabaci and IYSV levels were monitored in six seeded and six transplanted fields. We found significantly more thrips in transplanted fields early in the season, but by the end of the season seeded fields had higher levels of IYSV. The percentage of sample sites with IYSV-infected plants remained low (<12%) until August, when infection levels increased dramatically in some fields. The densities of adult and larval thrips in August and September were better predictors of final IYSV levels than early season thrips densities. For 2007 and 2008, the time onions were harvested may have been more important in determining IYSV levels than whether the onions were seeded or transplanted. Viruliferous thrips emigrating from harvested onion fields into nonharvested ones may be increasing the primary spread of IYSV in late-harvested onions. Managing T. tabaci populations before harvest, and manipulating the spatial arrangement of fields based on harvest date could mitigate the spread of IYS

Exploring VIIRS Continuity with MODIS in an Expedited Capability for Monitoring Drought-Related Vegetation Conditions

Vegetation has been effectively monitored using remote sensing time-series vegetation index (VI) data for several decades. Drought monitoring has been a common application with algorithms tuned to capturing anomalous temporal and spatial vegetation patterns. Drought stress models, such as the Vegetation Drought Response Index (VegDRI), often use VIs like the Normalized Difference Vegetation Index (NDVI). The EROS expedited Moderate Resolution Imaging Spectrora-diometer (eMODIS)-based, 7-day NDVI composites are integral to the VegDRI. As MODIS satellite platforms (Terra and Aqua) approach mission end, the Visible Infrared Imaging Radiometer Suite (VIIRS) presents an alternate NDVI source, with daily collection, similar band passes, and moderate spatial resolution. This study provides a statistical comparison between EROS expedited VIIRS (eVIIRS) 375-m and eMODIS 250-m and tests the suitability of replacing MODIS NDVI with VIIRS NDVI for drought monitoring and vegetation anomaly detection. For continuity with MODIS NDVI, we calculated a geometric mean regression adjustment algorithm using 375-m resolution for an eMODIS-like NDVI (eVIIRS’) eVIIRS’ = 0.9887 × eVIIRS − 0.0398. The resulting statistical comparisons (eVIIRS’ vs. eMODIS NDVI) showed correlations consistently greater than 0.84 throughout the three years studied. The eVIIRS’ VegDRI results characterized similar drought patterns and hotspots to the eMODIS-based VegDRI, with near zero bias

Evaluation of onion cultivars for resistance to onion thrips (Thysanoptera: Thripidae) and Iris Yellow spot virus.

ABSTRACT Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), a worldwide pest of onion, Allium cepa L., can reduce onion yield by Ͼ50% and be even more problematic when it transmits Iris yellow spot virus (family Bunyaviridae, genus Tospovirus, IYSV). Because T. tabaci is difÞcult to control with insecticides and other strategies, Þeld studies on onion, Allium cepa L., resistance to T. tabaci and IYSV were conducted in 2007 and 2008 in two locations in New York state. Forty-nine cultivars were evaluated for resistance by counting the number of larvae weekly and recording leaf damage. In another experiment, the impact of T. tabaci and IYSV on plant growth and yield was examined by spraying half of the plants with an insecticide. Eleven of the 49 cultivars had very little leaf damage and were considered resistant to T. tabaci. Visual assessment indicated that all resistant cultivars had yellow-greenÐ colored foliage, whereas the other 38 had blue-greenÐ colored foliage. The visual assessment of color agreed with data on color taken with a HunterLab Ultra Scan XE colorimeter. The onions ÔColorado 6Õ and ÔNMSU 03-52-1Õ had the lowest numbers of T. tabaci, suggesting strong antibiosis and/or antixenosis. The other nine cultivars had variable numbers of T. tabaci, indicating a possible combination of categories of resistance. In the nonprotected treatments there were signiÞcant reductions in plant height and plant weight in most of the resistant cultivars, but there were reductions in bulb weight only in a few of them. The average of plants infected with IYSV was 10% in 2007 and 60% in 2008. Our Þndings indicate potential for developing onion resistance to T. tabaci as part of an overall integrated pest management strategy but suggest difÞculties in identifying resistance to IYSV. RESUMEN El trips de la cebolla, Thrips tabaci Lindeman (Thysanoptera: Thripidae), una plaga a nivel mundial de la cebolla, Allium cepa L., causa pé rdidas en rendimiento (Ͼ50%) y puede ser aun mas problemática cuando transmite Iris yellow spot virus (familia Bunyaviridae, genero Tospovirus, IYSV) causante de la mancha amarilla. Debido a que T. tabaci es difṍcil de controlar con insecticidas y otros mé todos, estudios en campo sobre resistencia de la cebolla a T. tabaci se llevaron a cabo en 2007 y 2008 en dos lugares en el estado de Nueva York. Cuarenta y nueve genotipos fueron evaluados por medio de conteos de numero de larvas y evaluaciones del dañ o a la hoja. En otro experimento, se estimo el impacto de T. tabaci y el virus en el crecimiento de la planta y el rendimiento aplicando insecticida en la mitad de las plantas. Once de los 49 genotipos presentaron poco dañ o y fueron considerados resistentes a T. tabaci. Observaciones visuales indicaron que los genotipos resistentes tuvieron hojas de color verde-amarillo y los otros tuvieron hojas de color verde-azul, esto coincide con medidas de color tomadas con el &quot;HunterLab Ultra Scan XE colorimeter.&quot; ÔColorado 6Õ y ÔNMSU 03-52-1Õ tuvieron los nú meros mas bajos de T. tabaci, sugiriendo un alto nivel de antibiosis y/o antixenosis. Los otros nueve genotipos presentaron nú meros variables de T. tabaci indicando una posible combinació n de categorṍas de resistencia. Se observaron reducciones signiÞcativas en altura y peso de la planta en la mayorṍa de los genotipos resistentes, pero solo en unos pocos genotipos en el peso del bulbo. El promedio de plantas infectadas con IYSV fue del 10% en el 2007 y del 60% en el 2008. Estos resultados indican un desarrollo potencial de resistencia de la cebolla a T. tabaci como táctica para el manejo integrado de esta plaga, pero revelan diÞcultades para identiÞcar resistencia a IYSV

Forest Drought Response Index (ForDRI): A New Combined Model to Monitor Forest Drought in the Eastern United States

Monitoring drought impacts in forest ecosystems is a complex process because forest ecosystems are composed of different species with heterogeneous structural compositions. Even though forest drought status is a key control on the carbon cycle, very few indices exist to monitor and predict forest drought stress. The Forest Drought Indicator (ForDRI) is a new monitoring tool developed by the National Drought Mitigation Center (NDMC) to identify forest drought stress. ForDRI integrates 12 types of data, including satellite, climate, evaporative demand, ground water, and soil moisture, into a single hybrid index to estimate tree stress. The model uses Principal Component Analysis (PCA) to determine the contribution of each input variable based on its covariance in the historical records (2003–2017). A 15-year time series of 780 ForDRI maps at a weekly interval were produced. The ForDRI values at a 12.5km spatial resolution were compared with normalized weekly Bowen ratio data, a biophysically based indicator of stress, from nine AmeriFlux sites. There were strong and significant correlations between Bowen ratio data and ForDRI at sites that had experienced intense drought. In addition, tree ring annual increment data at eight sites in four eastern U.S. national parks were compared with ForDRI values at the corresponding sites. The correlation between ForDRI and tree ring increments at the selected eight sites during the summer season ranged between 0.46 and 0.75. Generally, the correlation between the ForDRI and normalized Bowen ratio or tree ring increment are reasonably good and indicate the usefulness of the ForDRI model for estimating drought stress and providing decision support on forest drought management

Potential caveats in land surface model evaluations using the US drought monitor: roles of base periods and drought indicators

The US drought monitor (USDM) has been widely used as an observational reference for evaluating land surface model (LSM) simulation of drought. This study investigates potential caveats in such evaluation when the USDM and LSMs use different base periods and drought indices to identify drought. The retrospective national water model (NWM) v2.0 simulation (1993&ndash;2018) was used to exemplify the evaluation, supplemented by North American land data assimilation system phase 2 (NLDAS-2). Over their common period (2000&ndash;2018), in distinct contrast with the USDM which shows high drought occurrence (&gt;50%) in the western half of the continental US (CONUS) and the southeastern US with low occurrence (&lt;30%) elsewhere, the NWM and NLDAS-2 based on soil moisture percentiles (SMPs) consistently show higher drought occurrence (30%&ndash;40%) in the central and southeastern US than the rest of the CONUS. Much of the differences between the LSMs and USDM, particularly the strong LSM underestimation of drought occurrence in the western and southeastern US, are not attributed to the LSM deficiencies, but rather the lack of long-term drought in the LSM simulations due to their relatively short lengths. Specifically, the USDM integrates drought indices with century-long periods of record, which enables it to capture both short-term (&lt;6 months) drought and long-term (⩾6 months) drought, whereas the relatively short retrospective simulations of the LSMs allows them to adequately capture short-term drought but not long-term drought. In addition, the USDM integrates many drought indices whereas the NWM results are solely based on the SMP, further adding to the inconsistency. The high occurrence of long-term drought in the western and southeastern US in the USDM is further found to be driven collectively by the post-2000 long-term warm sea surface temperature (SST) trend, cold Pacific decadal oscillation and warm Atlantic multi-decadal oscillation, all of which are typical leading patterns of global SST variability that can induce drought conditions in the western, central, and southeastern US. Our findings highlight the effects of the above caveats and suggest that LSM evaluation should stay qualitative when the caveats are considerable. &nbsp;</p

The Milky Way Tomography with SDSS: III. Stellar Kinematics

We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r<20 and proper-motion measurements derived from SDSS and POSS astrometry, including ~170,000 stars with radial-velocity measurements from the SDSS spectroscopic survey. Distances to stars are determined using a photometric parallax relation, covering a distance range from ~100 pc to 10 kpc over a quarter of the sky at high Galactic latitudes (|b|>20 degrees). We find that in the region defined by 1 kpc <Z< 5 kpc and 3 kpc <R< 13 kpc, the rotational velocity for disk stars smoothly decreases, and all three components of the velocity dispersion increase, with distance from the Galactic plane. In contrast, the velocity ellipsoid for halo stars is aligned with a spherical coordinate system and appears to be spatially invariant within the probed volume. The velocity distribution of nearby ($Z<1$ kpc) K/M stars is complex, and cannot be described by a standard Schwarzschild ellipsoid. For stars in a distance-limited subsample of stars (<100 pc), we detect a multimodal velocity distribution consistent with that seen by HIPPARCOS. This strong non-Gaussianity significantly affects the measurements of the velocity ellipsoid tilt and vertex deviation when using the Schwarzschild approximation. We develop and test a simple descriptive model for the overall kinematic behavior that captures these features over most of the probed volume, and can be used to search for substructure in kinematic and metallicity space. We use this model to predict further improvements in kinematic mapping of the Galaxy expected from Gaia and LSST.Comment: 90 pages, 26 figures, submitted to Ap

Plasma Insulin-like Growth Factors, Insulin-like Binding Protein-3, and Outcome in Metastatic Colorectal Cancer: Results from Intergroup Trial N9741

Insulin-like growth factor (IGF)-I and IGF-II stimulate neoplastic cell growth and inhibit apoptosis, whereas IGF-binding protein-3 (IGFBP-3) inhibits the bioavailability of IGF-I and has independent proapoptotic activity. We examined the influence of baseline plasma levels of IGF-I, IGF-II, IGFBP-3, and C-peptide on outcome among patients receiving first-line chemotherapy for metastatic colorectal cancer