Evolutionary and ecological implications of cardenolide sequestration in the monarch butterfly

Summary Monarch butterflies sequester cardenolides from their larval host plants in the milkweed genusAsclepias for use in defense against predation. Of 108Asclepias species in North America, monarchs are known to feed as larvae on 27. Research on 11 of these has shown that monarchs sequester cardenolides most effectively, to an asymptote of approximately 350 g/0.1 g dry butterfly, from plants with intermediate cardenolide contents rather than from those with very high or very low cardenolide contents. SinceAsclepias host plant species are distributed widely in space and time across the continent, monarchs exploit them by migration between breeding and overwintering areas. After overwintering in central Mexico, spring migrants east of the Rocky Mountains exploit three predominantAsclepias species in the southern USA that have moderately high cardenolide contents. Monarchs sequester cardenolides very effectively from these species. First generation butterflies are thus well protected against predators and continue the migration north. Across the northern USA and southern Canada most summer breeding occurs on a fourthAsclepias species and in autumn most of these monarchs migrate back to Mexican overwintering sites. The ecological implications of this cycle of cardenolide sequestration for the evolution of monarch migration are discussed.     

广西大瑶山蝶类调查

报道采自广西大瑶山蝶类１２４种（含亚种）,分属于１１科８１属。     

安徽省蝶类分布新记录

为了对安徽省蝶类资源及其分布进行深入研究,2001—2004年间对省内的蝶类资源作了进一步考查,共发现安徽省蝶类新记录23种另2型,其中有2种在《中国蝶类志》及《中国蝴蝶分类与鉴定》中未见记载.据统计,安徽省目前被记录的蝴蝶种类为12科157属309种.     

上海地区常见蝴蝶幼虫识别

对上海地区13种常见蝴蝶的幼虫进行了采集、饲养、鉴定，对每种幼虫的形态特征和主要寄主进行了描述，并附有整体图片，此外，还编写了上海地区常见的13种蝴蝶幼虫的检索表．     

Conchoecia mesadenia,a new species of abyssopelagic halocyprid ostracod related to C. dasyophthalma Müller, 1906

A new species of bathypelagic planktonic ostracod is described and a comparative study made between it and the closely-related species Conchoecia dasyophthalma Müller, 1906. The new species occurs deeper in the water column than C. dasyophthalma, it is smaller and can easily be recognized by its size and the unusual position of the right asymmetrical gland.     

高炉煤气流速对蝶阀区域粉尘沉降特性影响

高炉煤气含有大量粉尘,易沉积于管道三偏心蝶阀阀座密封面底部而造成阀板卡塞或损坏,影响高炉生产并造成严重经济损失。为获取管道内部高炉煤气流速对蝶阀区域粉尘沉降规律的影响机理,使用Pro/E建立了蝶阀及其区域流场的三维模型,基于ANSYS Workbench软件的FLUENT模块,采用标准k-ε湍流模型和DPM模型,对3种高炉煤气流速条件下的蝶阀区域粉尘运动轨迹进行了模拟分析。结果表明:流速为8m/s工况下,粉尘沉积质量随阀板开度增大而呈现先降后升的趋势,而12m/s和16m/s工况下,粉尘沉积质量随阀板开度增大而降低;阀板开度15°工况下,粉尘沉积率随高炉煤气流速增大而升高,而45°和75°工况下,粉尘沉积率随高炉煤气流速增大而降低。研究结果可为高炉煤气管道蝶阀区域粉尘自动清除装置的研制提供理论参考。     

横断山南部边缘地区蝶类调查研究

横断山南部边缘地区调查获得蝶类258种,隶属于10科,128属.其中蛱蝶最多,为65种;其次是灰蝶和弄蝶,分别是51种和50种,这3科蝴蝶占总数约2/3(166/258).优势种12个(4.7%)、常见种91个(35.3%)、少见种43个(16.7%)、罕见种112个(43.3%);个体数分布的规律接近对数级数法则.仅3个横断山特有种符合本调查区域处于边缘的性质,东洋种占总数的79.1%,说明了本地区蝴蝶东洋区的基本属性.     

基于FPGA的高速FFT处理器的设计与实现

针对高速实时信号处理的要求,提出了4096点快速傅立叶变换（FFT）处理器在现场可编程门阵列（FPGA）中的设计与实现方法。该方法采用了按频率抽取（DIF）基4算法和6级流水线结构,每级均采用FIFO存储器实现延迟功能,和四路转接器一起共同完成序列的码位抽取。为了避免数据溢出,采用块浮点结构来表示数据,节省了器件资源。实验结果表明,该方法在保证运算精度和实现复杂度的同时,提高了处理器的数据时钟频率和处理速度。     

Co-occurrence of three Aristolochia-feeding Papilionids (Archon apollinus,Zerynthia polyxena and Zerynthia cerisy) in Greek Thrace

Comparative studies of co-occurring species using overlapping resources may help in understanding the mechanisms supporting biotic diversity in species-rich regions, such as the Mediterranean region of Europe. Three Papilionidae butterflies, Archon apollinus, Zerynthia cerisy and Zerynthia polyxena, develop on Aristolochia plants and co-occur in Greek Thrace. We used mark–recapture to describe adult demography and dispersal, and searched for eggs and larvae to assess host plants and microhabitat preferences. Adult flight timing followed a sequence from earliest A. apollinus, through Z. polyxena to late Z. cerisy; this was more prominent in 2010 (warm early spring) than in 2011 (cold delayed spring). Population densities were highest for A. apollinus and lowest for Z. cerisy, whereas dispersal ability followed a reverse pattern. Adults of all three species crossed distances > 3 km and used all habitat types present. Four Aristolochia host plants were used at the study locality: small Aristolochia pallida, intermediate Aristolochia rotunda and Aristolochia hirta, and bulky, late-sprouting Aristolochia clematitis. Both A. apollinus and Z. polyxena used all four Aristolochia species, the former preferring Aristolochia rotunda and Aristolochia hirta, the latter Aristolochia rotunda and Aristolochia pallida. Zerynthia cerisy did not use the early-growing Aristolochia pallida while frequently using the late-growing Aristolochia clematitis. Further parameters affecting oviposition were biotope and canopy closure: early A. apollinus tolerated shady sites but late Z. cerisy avoided them. The simultaneous use of several host plants differing in phenology and habitat requirements, combined with rather high dispersal ability, arguably buffers the butterflies’ population dynamics against yearly variation in weather, while allowing efficient occupation of the diverse Mediterranean landscapes. The regional habitat diversity, created during millennia of human activity, is currently threatened by land abandonment, which may diminish the resource base for the studied butterflies.     

The utilization of two‐metre Countryside Stewardship Scheme grass margins by the gatekeeper Pyronia tithonus (L)

The utilization of 2‐m Countryside Stewardship Scheme (CSS) grass margins by Pyronia tithonus was investigated during the period 1997–2000 at three farms in Essex, UK. The aims of the research were to investigate whether 2‐m grass margins established using the CSS would provide suitable habitat for P. tithonus. Overall, there was no significant difference between P. tithonus abundance on the 2‐m grass margins and the control sections without margins, but significantly more P. tithonus were observed on the 2‐m grass margins in 2000 than in 1997. There was a strong relationship between P. tithonus abundance and the presence of hedgerows, and significantly more P. tithonus were recorded on 2‐m grass margins next to hedgerows than on 2‐m grass margins established in areas without adjacent hedgerows. It was suggested that P. tithonus would benefit most from habitats with 2‐m grass margins sown with a seed mixture containing a range of fine‐leaved grasses and wildflowers, next to a hedgerow, and managed in accordance with current practices.