河南省蜉蝣新种记述：昆虫纲：蜉蝣目

本文描述了采自河南省伏牛山地区的蜉蝣目３新种,即河南刺翅蜉Ｃｅｎｔｒｏｐｔｉｌｕｍ ｈｅｎａｎｅｎｓｉｓ ｓｐ．ｎｏｖ．长茎锯形蜉Ｓｅｒｒａｔｅｌｌａ ｌｏｎｇｉｐｅｎｎｉｓ ｓｐｎ．ｎｏｖ与黑铗细蜉Ｃａｅｎｉｓ ｎｉｇｒｏｆｏｒｃｅｐｓｓｐ．ｎｏｖ．讨论了它们区别于近似种的特征。     

蜉蝣目化石的研究进展

回顾了世界蜉蝣目化石研究简史,列出已发表的化石种类名录、分布及年代,共40科、124属、218种,其中包括中国的8属13种;描述了不同地质时期主要蜉蝣化石的分类单元和分布地区.简要介绍了蜉蝣分类系统及系统发育、稚虫食性、与其它昆虫的关系和古生态等方面的研究成果.在本文的第2部分,初步分析了目前该类群所存在的一些问题,并对今后的研究工作进行了展望.     

蜉蝣目昆虫染色体制备方法探讨

本文对蜉蝣目昆虫染色体制备方法进行了探讨。以蜉蝣稚虫为材料,经秋水仙素水溶液体外培养,采用显微操作技术,结合空气干燥法,可以获得形态良好、分散适中、着色清晰的生殖细胞染色体,为蜉蝣目昆虫细胞遗传学研究提供了一种简便有效的方法。     

中国扁蜉科二新种记述(昆虫纲,蜉蝣目)

记述采自中国香港的蜉蝣目扁蜉科2新种。根据稚虫和成虫的形态特征,详细描述了中国新纪录属康扁蜉属Compsoneuria 1新种：大埔浯康扁蜉Compsoneuria taipokauensis sp．nov．。该新种的成虫标本由稚虫在实验室内饲养而成。根据稚虫形态特征,详细描述了高翔蜉属1新种：箭鬃高翔蜉Epeorus sagittatus sp．nov．。     

现存蜉蝣翅基纵脉走向及愈合模式(昆虫纲：蜉蝣目)

有翅昆虫翅基纵脉的走向及愈合模式在系统发育重建中占有重要地位。然而,现存蜉蝣翅基纵脉的走向及愈合状况在大部分种类变化极大,无法推测其原始状况,只在极少数种类保留有部分可见残迹。中国拟短丝蜉Siphluriscus chinensis的翅基保留有独立的亚前缘脉弓、部分中脉M和肘脉Cu主干以及前中脉MA及径分脉Rs的走向痕迹。据此并结合红斑蜉Ephemera rufomaculata 和大网脉蜉Chromarcys magnifica翅基的相关特征,本文提出了蜉蝣目主要纵脉基部走向及愈合的基本模式,其要点有：中脉主干在基部与径脉主干独自发出后先接近或愈合后又分离、它们各自分成两支后的前中脉及径分脉又先愈合再分离、肘脉始终独立。这种中脉与径脉先接近或愈合后分离的模式非常接近新翅类的情况而与蜻蜓很不相同(在蜻蜓,中脉与肘脉在基部愈合) 。亚前缘脉弓的作用相信是加强了因翅基骨板发达而相互远离的纵脉间的连结作用。这个假说也可以来解释蜻蜓复杂脉相的形成原因。     

大鳃蜉属在中国的首次记录附一新种记述(蜉蝣目：小蜉科)

报道了中国一新纪录属,即大鳃明了 属Ｔｏｒｌｅｙａ Ｌｅｓｔａｇｅ（１９１７）,并详细描述了该属一新种,宽茎大鳃蜉Ｔ．ｇｒａｎｄｉｐｅｎｎｉｓ Ｚｈｏｕ,Ｓｕ ｅｔ Ｇｕｉ,ｓｐ．ｎｏｖ．的形态特征,并将其与近似种作了比较。     

埃蜉属一新种(蜉蝣目:多脉蜉科)(英文)

在海南省琼中县、陵水县和乐东县发现埃蜉属一新种,定名为海南埃蜉Ephoronhainanensissp.nov,新种与广泛分布于欧洲、亚洲北部（俄罗斯、蒙古、中国东北）的贞洁多脉蜉Ephoronvirgo（Oliver,1791）,相近似,但新种前翅MA脉分支点不与Rs脉第2次分支点位于同一纵线上,而在Rs脉第2次分支点之后;贞洁多脉蜉的前翅MA脉分支点与Rs脉第2次分支点位于同一纵线上。两者有明显的区别。     

中国四节蜉属一新种(蜉蝣目：四节蜉科)

报道了采自江苏省南京紫金山麓四节蜉属一新种逸仙四节蜉Baetis yixiani sp.nov.(成虫、稚虫),该新种稚虫近似于B. laetificus,主要区别为前者腹部第1～７节有7对鳃,而后者腹部第2～７节只有6对鳃。模式标本保存于南京师范大学生物系。     

昆虫界的“四不象”——一新建“螳Xiu目”昆虫简介

该文对2002年5月建立的昆虫新目－螳Xiu目Mantophasmatodea作了简单介绍,并建议了该目之中名。该目是昆虫纲中最小的目,目前已知2属3种,分布于非洲。     

Trade-offs in the response of mayflies to low oxygen and fish predation

Summary We examined how mayfly larvae (Ephemeroptera,Callibaetis montanus) balance the conflicting demands of avoiding both benthic hypoxia and fish predators. Using vertical oxygen and temperature gradients typical of ice-covered lakes, we observed the behavior of mayflies in the presence and absence of fish. In the absence of fish and with adequate oxygen, mayflies spent most of the time on the bottom substrate. As benthic oxygen concentration declined, mayflies increased their activity and moved up in the water column. In the presence of fish and with adequate oxygen, mayflies spent even more time associated with the bottom substrate and reduced their activity levels. As benthic oxygen concentrations declined, mayflies increased their activity and moved up in the water column, but to a lesser extent than when fish were absent. Because of this depression in activity and reluctance to leave the bottom substrate, mayflies endured lower oxygen concentrations in the face of predation threat relative to when fish were absent. Despite this trade-off, benthic hypoxia resulted in increased mortality due to fish predation. Because benthic invertebrates vary in their ability to tolerate hypoxia and in their vulnerability to fish predators, periods of benthic hypoxia could lead to selective predation on some taxa and be an important force structuring benthic invertebrate assemblages.     

Functional morphology of burrowing in the mayflies Hexagenia limbata and Pentagenia vittigera

A video system, consisting of a high-resolution, infrared-sensitive, surveillance television camera, time-date generator, video recorder and high-resolution monitor, was developed for naturalistic observation of the subaquatic activities of larval mayflies. Exemplars were isolated from light, sound and mechanical disturbance, and their burrowing behaviour was recorded for subsequent slow-motion analysis. Larvae of silt-inhabiting Hexagenia limbata were observed to be ploughers that displaced and compacted soft substrate in the excavation of an open tunnel. The head and prothoracic legs had the principal roles in substrate displacement, while the mesothoracic and metathoracic legs drove the body forward. Five stereotyped burrowing cycles were distinguished, although one, termed the Alternate Undercut because of the motions of the prothoracic legs, predominated. Larvae of clay-inhabiting Pentagenia vittigera were observed to chisel and gouge out compacted substrates, also creating an open burrow. Their mandibular tusks were used to dislodge substrate, while the prothoracic legs displaced loosened substrate and widened the opening. The body was driven forward either by strong abdominal flexions or by activity of the mesothoracic and metathoracic legs. Four burrowing cycles were distinguished, two of which, the Tusk Gouge and the Chisel and Sweep, predominated. Differences in proportion and armature of the head and appendages correlated with the different substrate types excavated.     

Global diversity of mayflies (Ephemeroptera, Insecta) in freshwater

The extant global Ephemeroptera fauna is represented by over 3,000 described species in 42 families and more than 400 genera. The highest generic diversity occurs in the Neotropics, with a correspondingly high species diversity, while the Palaearctic has the lowest generic diversity, but a high species diversity. Such distribution patterns may relate to how long evolutionary processes have been carrying on in isolation in a bioregion. Over an extended period, there may be extinction of species, but evolution of more genera. Dramatic extinction events such as the K-T mass extinction have affected current mayfly diversity and distribution. Climatic history plays an important role in the rate of speciation in an area, with regions which have been climatically stable over long periods having fewer species per genus, when compared to regions subjected to climatic stresses, such as glaciation. A total of 13 families are endemic to specific bioregions, with eight among them being monospecific. Most of these have restricted distributions which may be the result of them being the relict of a previously more diverse, but presently almost completely extinct family, or may be the consequence of vicariance events, resulting from evolution due to long-term isolation. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

波纹杂毛虫生物学特性与防治

对波纹杂毛虫幼期形态特征作了详细描述;该虫在福建省1a发生2代,以3—4龄幼虫在地被物中越冬;系统观察了各龄幼虫的取食过程并计算了取食量。开展了室内外防治试验。为该虫综合防治提供了科学依据。     

Life histories, production dynamics and resource utilisation of mayflies (Ephemeroptera) in two tropical Asian forest streams

SUMMARY 1. A 2‐year study of the life histories, production dynamics and resource utilisation of five mayfly species was undertaken in two forest streams in Hong Kong [Tai Po Kau Forest Stream (TPKFS) and Shing Mun River (SMR)]. Afronurus sp. and Cinygmina sp. (Heptageniidae), Procloeon sp. and Baetiella pseudofrequenta (Baetidae), and Choroterpes sp. (Leptophlebiidae) were abundant in both streams and contributed more than 50% of the total mayfly populations. 2. All species had asynchronous larval development with recruitment occurring throughout the year. Mean annual production (all mayflies combined) was 3.1 and 2.0 g dry weight m^?2 year^?1 in SMR and TPKFS, respectively – the higher value at SMR reflecting greater mayfly densities – with more than 70% of production occurring during the wet season. Mayfly production varied between years, decreasing by 5% in TPKFS and 43% in SMR during 1996–97, reflecting lower densities of heptageniids relative to 1995–96. Annual biomass turnover rates (P/B) were high in both sites ranging from 27.2 to 94.6 in TPKFS (Cinygmina sp. and Procloeon sp.) and from 31.8 to 109.8 in SMR (Cinygmina sp. and B. pseudofrequenta). 3. Patterns of daily production in both streams showed that Afronurus sp., Cinygmina sp. and Choroterpes sp. were most productive during the wet season, while Procloeon sp. maintained high production levels throughout the year. The highest daily production of B. pseudofrequenta occurred during the wet season in TPKFS, but in the dry season at SMR. Temporal overlap in production and hence resource utilisation in both streams, calculated using the proportional similarity index (PS), ranged from 0.39 to 0.81. It was highest (0.63–0.81) between pairs of species of Heptageniidae and Baetidae, and lowest between Choroterpes sp. and other mayflies (0.39–0.61). No clear temporal segregation was observed among any species. However, when using the fraction of production attributable to each food, lower PS values were obtained for all species in both sites. In SMR, trophic segregation may have occurred between the two species pairs Procloeon sp.–Cinygmina sp. and Procloeon sp.–Choroterpes sp. (PS=0.17 and 0.03, respectively). 4. A combination of production data and information on the stable isotope signature of mayflies revealed that, during both the wet and dry seasons, more than 50% of total mayfly production in TPKFS was derived from autochthonous foods. In SMR, 68% of production was supported by allochthonous foods during the wet season, and 72% by autochthonous sources in the dry season. Considering that more than 70% of the total production occurred in the wet season, the trophic basis of mayfly production in SMR is mostly allochthonous (58%) while in TPKFS it is mainly of autochthonous origin (66%). The year‐round importance of autochthonous foods in shaded streams such as TPKFS is surprising, but the wet season contribution of allochthonous foods (especially in SMR) may have resulted from depletion of algal biomass during spates.     

谢氏宽漠王的生物学特性及行为

谢氏宽漠王Mantichorulasemenowi是荒漠半荒漠地区的有害昆虫之一。该文主要探讨了该虫的生物学特性和部分行为。该虫 2年发生 1代 ,世代不整齐 ,以成、幼虫越冬。卵期 1 0～ 1 8d ,幼虫共有 7龄 ,化蛹时间为 6月下旬至 8月上旬 ,蛹经过 1 1～ 1 7d羽化为成虫。食性杂。喜光 ,活动有明显的节律性。     

Formation of the chick primitive streak as studied in computer simulations

We have used a computer simulation system to examine formation of the chick primitive streak and to test the proposal (Wei and Mikawa Development 127 (2000) 87) that oriented cell division could account for primitive streak elongation. We find that this proposal is inadequate to explain elongation of the streak. In contrast, a correctly patterned model streak can be generated if two putative mechanisms are operative. First, a subpopulation of precursor cells that is known to contribute to the streak is assigned a specific, but simple, movement pattern. Second, additional cells within the epiblast are allowed to incorporate into the streak based on near-neighbor relations. In this model, the streak is cast as a steady-state system with continuous recruitment of neighboring epiblast cells, egress of cells into deeper layers and an internal pattern of cell movement. The model accurately portrays elongation and maintenance of a robust streak, changes in the composition of the streak and defects in the streak after experimental manipulation.