Millennium tree-ring reconstruction of drought variability in the eastern Qilian Mountains, northwest China

Knowledge of natural long-term drought variability is essential for water resource management and planning, especially in arid and sub-arid regions of the world. In the eastern Qilian Mountains of China, long-term drought variability based on high-resolution proxy records such as tree-ring data are still scarce to date. Here we present a new tree-ring chronology from the eastern Qilian Mountains which provides a valuable 1,002-year record (1009–2010 CE) of drought variability. The new reconstruction of June–July 5-month scale standardized precipitation and evapotranspiration index is the first millennium tree-ring estimate of past climate developed in the eastern Qilian Mountains. The record shows that this region has experienced several persistent droughts and pluvials over the past millennium, with significantly drier climate during the fifteenth century and dramatic wetting since the nineteenth century. The low frequency generally agrees with other nearby studies based on both tree-ring data and other proxy data

A dicistrovirus increases pupal mortality in Spodoptera frugiperda by suppressing protease activity and inhibiting larval diet consumption

Understanding interactions between viruses and their hosts is conducive to enabling better application of viruses as biocontrol agents. Certain viruses carried by parasitic wasps enhance the parasitic efficiency of wasp-larvae by protecting them against the immune system of their Lepidopteran host. However, the relationship between prey pests and viruses found in predatory natural enemies remains unclear. Herein, we report the interaction between Arma chinensis virus-1 (AcV-1), originally isolated from a predatory natural enemy, Arma chinensis (Hemiptera: Pentatomidae), and one of its prey species, Spodoptera frugiperda (Lepidoptera: Noctuidae). The results showed that the AcV-1 virus appeared harmful to the novel host S. frugiperda by inhibiting larval diet consumption and increasing pupal mortality. Meanwhile, sequencing data indicated that the virus altered the gene expression profiles of S. frugiperda. KEGG analysis showed that the proteasome and phagosome pathways related to protein degradation and immune response were significantly enriched. Although the expression levels of digestive enzyme genes did not change significantly, the total protease activity of AcV-1 virus-positive individuals was significantly decreased, suggesting that the virus inhibited diet consumption of S. frugiperda via the down-regulation of digestive enzyme activities. These results indicate that a virus initially isolated in a predatory natural enemy can decrease the fitness of its prey species. The virus was found to impact the host proteasome and phagosome pathways related to protein degradation and immunity, providing a potential mechanism to enhance controlling efficiency.</p

Modeling the epidemiological history of plague in Central Asia: Palaeoclimatic forcing on a disease system over the past millennium

<p>Abstract</p> <p>Background</p> <p>Human cases of plague (<it>Yersinia pestis</it>) infection originate, ultimately, in the bacterium's wildlife host populations. The epidemiological dynamics of the wildlife reservoir therefore determine the abundance, distribution and evolution of the pathogen, which in turn shape the frequency, distribution and virulence of human cases. Earlier studies have shown clear evidence of climatic forcing on contemporary plague abundance in rodents and humans.</p> <p>Results</p> <p>We find that high-resolution palaeoclimatic indices correlate with plague prevalence and population density in a major plague host species, the great gerbil (<it>Rhombomys opimus</it>), over 1949-1995. Climate-driven models trained on these data predict independent data on human plague cases in early 20th-century Kazakhstan from 1904-1948, suggesting a consistent impact of climate on large-scale wildlife reservoir dynamics influencing human epidemics. Extending the models further back in time, we also find correspondence between their predictions and qualitative records of plague epidemics over the past 1500 years.</p> <p>Conclusions</p> <p>Central Asian climate fluctuations appear to have had significant influences on regional human plague frequency in the first part of the 20th century, and probably over the past 1500 years. This first attempt at ecoepidemiological reconstruction of historical disease activity may shed some light on how long-term plague epidemiology interacts with human activity. As plague activity in Central Asia seems to have followed climate fluctuations over the past centuries, we may expect global warming to have an impact upon future plague epidemiology, probably sustaining or increasing plague activity in the region, at least in the rodent reservoirs, in the coming decades.</p> <p>See commentary: <url>http://www.biomedcentral.com/1741-7007/8/108</url></p

A Comparative Study on Factors Influencing Food Security in China and India

This paper analyzes and compares the key factors influencing food security in two populous countries (China and India), and categorizes them into three types: agricultural production, economic development and income level, and income distribution. Using the prevalence of undernourishment as an indicator of food security, the paper empirically tests the degree of impact of various factors on food security in both countries using Tobit regression and Newey regression methods. The study finds that improving the level of economic development can significantly enhance food security in both countries; reducing the Gini coefficient has a significant impact on India, but not on China; increasing the agricultural production per capita has a much greater effect on China than on India. Therefore, both countries should take measures that are both similar and different according to their national conditions to improve their food security level

Analysis of the Evolution of Land-Use Types in the Qilian Mountains from 1980 to 2020

The Qilian Mountains (QMs), located in the northeast part of the Qinghai–Tibetan Plateau in China, have a fragile ecological environment, complex and sensitive climate, and diverse land-cover types. It plays an important role in the “Qinghai–Tibetan Plateau Ecological Barrier” and “Northern Sand Control Belt” in China’s “two screens and three belts” ecological security strategy. Based on land use data of 1980, 1990, 1995, 2000, 2005, 2010, 2015, and 2020, we utilized GIS technology, land use dynamic degree, and land use transition matrixes to analyze the spatial and temporal evolution of land use in the QMs from 1980 to 2020. The results showed the following: (1) From 1980 to 2020, grassland, forest land, and unused land were the main land-use types in the QMs, and the proportion of construction land accounted for only 0.31% of all land-use types. (2) The single land use dynamic degree showed that the dynamic degree of construction land was the highest and the fastest change rate from 2010 to 2015. The comprehensive land use dynamic degree showed that the intensity of land-use change was relatively drastic in the three time periods of 1990–1995, 1995–2000, and 2015–2020. (3) The land-use types in the study area switched infrequently during 2000–2005, 2005–2010, and 2010–2015. (4) The main transition directions of land-use types were grassland and unused land to other land-use types. These changes altered the spatial distributions of different land-use types. The study is critical for understanding the spatial and temporal change patterns of land-use change in the QMs and providing guidance for the optimization of land use in the study area and the improvement of regional eco-environmental protection

Analysis of the Evolution of Land-Use Types in the Qilian Mountains from 1980 to 2020

The Qilian Mountains (QMs), located in the northeast part of the Qinghai&ndash;Tibetan Plateau in China, have a fragile ecological environment, complex and sensitive climate, and diverse land-cover types. It plays an important role in the &ldquo;Qinghai&ndash;Tibetan Plateau Ecological Barrier&rdquo; and &ldquo;Northern Sand Control Belt&rdquo; in China&rsquo;s &ldquo;two screens and three belts&rdquo; ecological security strategy. Based on land use data of 1980, 1990, 1995, 2000, 2005, 2010, 2015, and 2020, we utilized GIS technology, land use dynamic degree, and land use transition matrixes to analyze the spatial and temporal evolution of land use in the QMs from 1980 to 2020. The results showed the following: (1) From 1980 to 2020, grassland, forest land, and unused land were the main land-use types in the QMs, and the proportion of construction land accounted for only 0.31% of all land-use types. (2) The single land use dynamic degree showed that the dynamic degree of construction land was the highest and the fastest change rate from 2010 to 2015. The comprehensive land use dynamic degree showed that the intensity of land-use change was relatively drastic in the three time periods of 1990&ndash;1995, 1995&ndash;2000, and 2015&ndash;2020. (3) The land-use types in the study area switched infrequently during 2000&ndash;2005, 2005&ndash;2010, and 2010&ndash;2015. (4) The main transition directions of land-use types were grassland and unused land to other land-use types. These changes altered the spatial distributions of different land-use types. The study is critical for understanding the spatial and temporal change patterns of land-use change in the QMs and providing guidance for the optimization of land use in the study area and the improvement of regional eco-environmental protection

Analysis of the Evolution of Land-Use Types in the Qilian Mountains from 1980 to 2020

The Qilian Mountains (QMs), located in the northeast part of the Qinghai–Tibetan Plateau in China, have a fragile ecological environment, complex and sensitive climate, and diverse land-cover types. It plays an important role in the “Qinghai–Tibetan Plateau Ecological Barrier” and “Northern Sand Control Belt” in China’s “two screens and three belts” ecological security strategy. Based on land use data of 1980, 1990, 1995, 2000, 2005, 2010, 2015, and 2020, we utilized GIS technology, land use dynamic degree, and land use transition matrixes to analyze the spatial and temporal evolution of land use in the QMs from 1980 to 2020. The results showed the following: (1) From 1980 to 2020, grassland, forest land, and unused land were the main land-use types in the QMs, and the proportion of construction land accounted for only 0.31% of all land-use types. (2) The single land use dynamic degree showed that the dynamic degree of construction land was the highest and the fastest change rate from 2010 to 2015. The comprehensive land use dynamic degree showed that the intensity of land-use change was relatively drastic in the three time periods of 1990–1995, 1995–2000, and 2015–2020. (3) The land-use types in the study area switched infrequently during 2000–2005, 2005–2010, and 2010–2015. (4) The main transition directions of land-use types were grassland and unused land to other land-use types. These changes altered the spatial distributions of different land-use types. The study is critical for understanding the spatial and temporal change patterns of land-use change in the QMs and providing guidance for the optimization of land use in the study area and the improvement of regional eco-environmental protection.</jats:p