Changing patterns of the East Asian monsoon drive shifts in migration and abundance of a globally important rice pest

Numerous insects including pests and beneficial species undertake windborne migrations over hundreds of kilometers. In East Asia, climate-induced changes in large-scale atmospheric circulation systems are affecting wind-fields and precipitation zones and these, in turn, are changing migration patterns. We examined the consequences in a serious rice pest, the brown planthopper (BPH, Nilaparvata lugens) in East China. BPH cannot overwinter in temperate East Asia, and infestations there are initiated by several waves of windborne spring or summer migrants originating from tropical areas in Indochina. The East Asian summer monsoon, characterized by abundant rainfall and southerly winds, is of critical importance for these northward movements. We analyzed a 42-year dataset of meteorological parameters and catches of BPH from a standardized network of 341 light-traps in South and East China. We show that south of the Yangtze River during summer, southwesterly winds have weakened and rainfall increased, while the summer precipitation has decreased further north on the Jianghuai Plain. Together, these changes have resulted in shorter migratory journeys for BPH leaving South China. As a result, pest outbreaks of BPH in the key rice-growing area of the Lower Yangtze River Valley (LYRV) have declined since 2001. We show that these changes to the East Asian summer monsoon weather parameters are driven by shifts in the position and intensity of the Western Pacific subtropical high (WPSH) system that have occurred during the last 20 years. As a result, the relationship between WPSH intensity and BPH immigration that was previously used to predict the size of the immigration to the LYRV has now broken down. Our results demonstrate that migration patterns of a serious rice pest have shifted in response to the climate-induced changes in precipitation and wind pattern, with significant consequences for the population management of migratory pests.     

Impact of the green tea ingredient epigallocatechin gallate and a short pentapeptide (Ile-Ile-Ala-Glu-Lys) on the structural organization of mixed micelles and the related uptake of cholesterol

Background

High levels of blood cholesterol are conventionally linked to an increased risk of developing cardiovascular disease (Grundy, 1986). Here we examine the molecular mode of action of natural products with known cholesterol-lowering activity, such as for example the green tea ingredient epigallocatechin gallate and a short pentapeptide, Ile-Ile-Ala-Glu-Lys.

Early gap successional pathways in a Fagus-Acer forest preserve: pattern and determinants

Abstract. Many theories of forest succession imply that terrestrial plant community composition within a region tends to converge toward a climax community. That is, given similar climatic and edaphic conditions, succession at different sites within an area will lead to comparable species compositions, a pattern referred to as successional convergence. In this study, we examine changes in plant composition within forest canopy gaps over a 17-yr period to identify potential patterns of successional convergence and to ascertain the factors controlling the successional pathway. To do so, we: (1) sampled 36 forest canopy gaps in Hueston Woods Nature Preserve in 1977, 1981, 1985, 1989 and 1993, (2) evaluated changes in the similarity of gap composition over this period, and (3) examined gap composition in each year as a function of variables describing gap habitat, seed source proximity, and disturbance history. Results indicated an initial pattern of successional divergence, with gaps exhibiting increased dissimilarity over the first 10–12 years of succession. We attribute this initial period of divergence to the effects of differential seed inputs from edge individuals and heterogeneity of available light due to differences in gap size. Recent surveys, however, indicated that gap composition has become more similar as competition within gaps has become more intense. In these samples, gap composition is closely linked to site conditions, including slope, soil conditions, and site exposure. Finally, while these patterns may suggest equilibrium-oriented dynamics, non-equilibrium processes such as repeat disturbances are also evident at Hueston Woods and will likely play an important role in determining future successional pathways.     

On the encoding of movement vectors by honeybees. Are distance and direction represented independently?

Honeybees flying repeatedly over the same trajectory link it to an associated visual stimulus such that on viewing the stimulus they perform a trajectory in the habitual direction. To test if trajectory length can also be linked to a visual stimulus, bees were trained to fly through a multi-comparmented maze. Bees flew through a multi-compartmented maze. In one compartment a short trajectory could be linked to a stripe pattern oriented at 45° to the horizontal. In another compartment a longer trajectory could be linked to 135° stripes. Bees made both associations: their trajectories were short when viewing 45° stripes and longer when viewing 135° stripes. 90° stripes evoked trajectories of intermediate length.To test if distance and direction are linked independently to stripe orientation, a bee's trajectory was linked to 135° stripes in one compartment and to 45° stripes in another. These trajectories were the same length but differed in their horizontal direction by 60° or by 120°. 90° stripes evoked trajectories of intermediate direction which were shorter than those elicited by either training pattern. Bees were also trained to generate one long and one short trajectory with directions 120° apart. The trajectories elicited by 90° stripes were then biased towards the direction of the long training vector. Length and direction are not treated separately. The rules for combining trajectories resemble those of vector averaging.     

A method for the analysis of temporal changes in vegetation pattern at the landscape level

A new approach to study temporary changes in small landscape units is proposed, based on vegetation-complex relevés (sigma relevés). The method is introduced using extensively grazed or abandoned heathland and Nardus-sward landscapes in the Black Forest as examples. Thirty-six sigma relevés of the years 1979–80 are compared with those of 1989–90. Each of the compared plot areas covers on the average 2–4 hectares, and has a diversity of about 20 different vegetation types. The vegetation complex relevés can be ordered to 3 different types which characterize landscape ecological zones dependant on former rural management.As a result of the comparison 2 main developments which have a spatial differentiation in the Black Forest are confirmed and documentated:

Vegetation differentiation and secondary succession on a limestone hill in southern Poland

Abstract. The vegetation of the SkoHzanka Reserve, situated on a limestone hill near Krakow, was examined over a 30 year period, using the Braun-Blanquet method. With the help of a numerical classification eight types of grassland communities were distinguished, belonging to the classes Sedo-Scleranthetea, Nardo-Callunetea and Festuco-Brometea, and 11 types of woodland communities, both remnants of ancient woodlands from the classes Querco-Fagetea and Vaccinio-Piceetea and more recent woods. In the case of grasslands the results of detrended correspondence analysis (DCA) indicated that the largest variation was associated with the soil type. Woods on sandy soils are very different from those on calcareous soils, and the younger recent woods are very different from the ancient woodlands. An analysis of historical cartographic material and aerial photographs shows that in the last few decades the area of recent woods has increased considerably at the expense of grasslands. Changes in species diversity in the woods during secondary succession and their successional convergence were examined and discussed. It was found that young and mature woods on sandy soils are more similar to each other than young and mature woods on calcareous soils. These differences are mainly related to the fact that many woodland herb species growing in rich, broadleaved ancient woods are unable to colonize recent woods since they have a limited colonization capacity.     

Evolution of major pattern models and processes of alluvial forest of the Rhine in the rift valley (France/Germany)

In the rift valley (North-East of France/South-West of Germany), the Rhine runs freely for 300 km from South to North. The absence of natural obstacles allows the development of a very regular profile of the river. We have therefore an opportunity to study very gradual modifications of the alluvial forest communities of the fluvial corridor from upstream to downstream, according to the gradual evolution of the ecological factors, related to slope decrease and hydrological modifications.We describe, from Basel to Mainz:

四川中亚热带扁刺栲-华木荷群系不同演替阶段林内小气候的比较

 对四川瓦屋山地区扁刺栲(Castanopsis platyacantha)-华木荷(Schima sinense)群系不同演替阶段（灌木、10年和40年生扁刺栲-华木荷群落）的林内小气候进行了连续2年的定位观测研究。主要结果是：40年生的扁刺栲-华木荷群落内的地温、空气温度、相对湿度、光照强度和降雨等气候指标的数量大小及其变幅最低,10年生的次之,灌丛的最大。这些结果暗示了扁刺栲-华木荷群落在恢复演替过程中,随着植被的发育和各层次结构的完善,林内小气候环境朝着更为阴、凉、冷、湿的环境演进,且其波动性减弱,