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51.
In August 2008, the first detection of the spotted wing drosophila, Drosophila suzukii, to the North America mainland in California caused great concern, as the fly was found infesting a variety of commercial fruits. Subsequent detections followed in Oregon, Washington, Florida and British Columbia in 2009; in Utah, North Carolina, South Carolina, Michigan, and Louisiana in 2010; and in Virginia, Montana, Wisconsin, Pennsylvania, New Jersey, Maryland and Mexico in 2011. In Europe, it has been detected in Italy and Spain in 2009 and in France in 2010. Economic costs to the grower from D. suzukii include the increased cost of production (increased labor and materials for chemical inputs, monitoring and other management tools) and crop loss. An effective response to the invasion of D. suzukii requires proper taxonomic identification at the initial phase, understanding basic biology and phenology, developing management tools, transferring information and technology quickly to user groups, and evaluating the impact of the research and extension program on an economic, social, and environmental level. As D. suzukii continues to expand its range, steps must be initiated in each new region to educate and inform the public as well as formulate management tactics suitable for the crops and growing conditions in each.  相似文献   
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Multi-trait indices (MTI) weigh traits based on their importance to facilitate selection in plant and animal improvement. In animal breeding, economic values are used to develop MTIs. For vegetables, economic data valuing traits are rarely available. We posit that varieties with traits valued by growers and processors achieve higher market share and longer life span. Our objective was to develop MTIs predicting success of tomato varieties. Historical data for the California processing tomato industry from 1992 to 2013 provided measurements for yield, soluble solids (Brix), color, pH, market share, and life span for 258 varieties. We used random models to estimate best linear unbiased predictors (BLUPs) for phenotypic traits of each variety, and evaluated trends over time. Yield has been increasing from 2006, while Brix stayed constant. Because yield and Brix are negatively correlated, this trend suggests that Brix influenced selection. The average number of resistances reported in varieties ranking in the top ten increased from 2 to 4.5 between 1992 and 2013. MTIs predicting success from phenotypic traits were developed with general linear models and tested using leave-one-out cross validation. MTIs weighing yield, Brix, pH and color were significantly correlated to success metrics and selected a significantly higher proportion of successful varieties relative to random sampling. The index multiplying yield and brix, suggested in the literature, was not significantly correlated with variety success. The MTIs suggested that fruit quality had less of an influence on variety success than yield. The MTIs developed could help improve gain under selection for quality traits in addition to yield.  相似文献   
53.
Data on 4,411 male and 4,148 female progeny from the University of Missouri-Columbia swine research herd were analyzed to evaluate the associations of sire, breed, weight at birth, and sex of the pigs with the development of congenital splayleg. Statistically significant differences in frequency of splayleg were found among sires and among breeds indicating a genetic influence. Differences in frequencies among male vs female progeny also were found to be statistically significant. The overall frequency among male progeny was 1.74 times that observed among female progeny. Comparison of birth weights of splayleg vs normal pigs showed birth weights to be statistically significantly smaller among affected pigs.  相似文献   
54.
低湿地与土壤湿度的卫星遥感监测与制图   总被引:8,自引:0,他引:8       下载免费PDF全文
戴昌达  T.Vogt 《土壤学报》1995,32(4):377-382
本文介绍应用陆地卫生TM图象数据监测法国莱茵河谷地土壤湿度变化,绘制1:50,000低湿地分布图的技术方法。对夏、秋两个时相的TM图像进行K-L变换等应用处理,获得的第3主分量集中了土壤湿度差异的信息。把两个时相的第3主人量精确配准后,以Hyperboxes分类器进行湿度分类,分出水体、恒湿地、夏秋季潮湿地、冬春季潮湿地、恒干地等5个湿度类别。经实地检验准确可信,表明此方法适合于土壤湿度变化监测与  相似文献   
55.
Cutting scores for 3399 horses representing 327 different sires from the NCHA World Championship Futurities of 1975 through 1983 were used to calculate heritability and yearly change in scores. The analysis yielded a heritability estimate of 19%±5%. Appropriate selection schemes, then, should be successful in bringing about an improvement in cutting score. The analysis of yearly trend, however, indicates that average cutting scores at NCHA futurities are decreasing by 0.78 points per year.  相似文献   
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Seven sediment cores were collected along a transect about20 km off from the mouth of the Po River, in the northernAdriatic Sea (Italy). Cores were characterised by differentdepositional sequences associated with late Pleistocene-Holocene lowstand (LST), transgressive (TST) and highstand (HST) system tracts. Sediment samples were analysed for mercury, copper, nickel, chromium, manganese and iron, aswell as for total organic matter. Metal distributiongenerally showed vertical and spatial variability ascribed tograin size effects with no significant anthropogenicperturbation. Conversely, mercury showed vertical profilescharacterised by surface enrichment, with concentrations inthe upper layer (50–230 ng g-1) exceeding 3–11 times the background value of 20 ng g-1 determined in bottomcores. Surface maxima were attributed to anthropogenic mercurydelivered mainly by the Po River.  相似文献   
59.
Landscape Ecology - Few habitat modeling studies consider multiple spatial or temporal scales; less identify the operative scale of an organism's response to predictor variables. Optimizing...  相似文献   
60.
Landscape Ecology - The southeastern U.S. experiences tornadoes and severe thunderstorms that can economic and ecological damages to forest stands resulting in loss of timber, reduction in...  相似文献   
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