蜉蝣属一新种(蜉蝣目:蜉蝣科)(英文)

详细描述了采自安徽黄土坑的一新种：黑翅蜉（Ephemeranigropterasp.nov）的形态特征,并对前人划分蜉蝣属各亚属的标准作了修订。认为将前翅MP2脉与CuA脉在基部连接与否作为划分蜉蝣亚属的标准比较可行。这样,黑翅蜉应归入到蜉蝣属叉蜉亚属（Dicrephemera）。黑翅蜉区别于蜉蝣属其它种的特征为：1）雄成虫前翅外侧大部分呈棕红色,半透明,雌成虫的前翅只具少许斑点,翅透明;2）后翅外侧缘具棕红色斑纹,半透明,而雌成虫后翅不具斑纹,透明,3）雄、雌成虫腹部背板上的斑纹形式及排列;4）雄成虫的尾铗大部分为黑色;5）雄成虫的阳茎的形状独特,且两阳茎紧靠。     

黑竹冲河小裳蜉(Leptophlebia sp.)和蜉蝣(Ephemera sp.)周年生产量

大型底栖动物在河流生态系统中发挥着重要作用。2003年6月至2004年6月间对汉江流域2级河流--黑竹冲河大型底栖动物群落优势种类的生产力进行了为期一周年的调查研究。结果表明,主要优势种小裳蜉(Leptophlebia sp.)和蜉蝣(Ephemera sp.)的生活史均为一年两代,蜉蝣的两个代之间界限比较明显;小裳蜉成虫羽化主要发生在秋季和冬季,而蜉蝣成虫羽化主要发生在夏季和冬季。小裳蜉和蜉蝣种群的生物量和多度均出现两次峰值。采用体长频率法(size-frequencymethod)测算的周年生产量分别为:小裳蜉,38.0362g·m^-2·a^-1,P/B为11.4;蜉蝣,76.0318g·m^-2·a^-1,P/B为11.8。     

南京宽基属蜉蝣一新种(蜉蝣目:细裳蜉科)

1978年5月下旬至11月初在南京中山陵一个小溪的石块下先后采集蜉蝣稚虫十次,计采到宽基属(Choroterpes)蜉蝣稚虫共280头,经带回实验室饲养,其中羽化为亚成虫者共18头(12,6),羽化为成虫者共55头(48,7)。经鉴定,为一新种,描记于后。宽基属是一个广布属,除日人上野益三(Ueno)于1928年描述过我台     

中国蜉蝣一新属新种(蜉蝣目:河花蜉科)

河花蜉科(Potamanthidae)目前在全世界已报道了6属31种,其中在我国发现的有似河花蜉属Potamanthodes新似河花蜉属Neopotamanthodes和Rhoenanthopsis属共3属9种。作者从1982—1984年采自秦岭,大别山的标本中发现一新属新种。因为蜉蝣具有独特的变态类型(原变态),目前把成虫、亚成虫和成熟稚虫以及卵的特征用于分类已成为世界蜉蝣分类研究的趋势。而在国内由于此项工作起步很晚,以前的分类大多只限于对成虫或亚成虫的单一描述。本文则对新属新种的各虫态都进行了记述。     

知识果味派

正哪种动物活得长?哪种动物活得短?最近,火狐狸姐姐收到了好多与动物寿命有关的问题。在经历了毒、怪、便便和奇幻动物之后,哥迷们的口味终于回归了,开始问一些让火狐狸姐姐不那么冒汗的问题。蜉蝣真的"朝生暮死"吗?这个说法嘛,其实半对半错。说它对呢,是因为蜉蝣的一生经过卵、幼虫和成虫几个阶段,当它变为成虫后,只能活几个小时到一天的时间。这么说起     

中国蜉蝣属两异名及一新种记述(蜉蝣目,蜉蝣科)

我国大陆蜉蝣科蜉蝣属Ephemera中的张家界蜉E．zhangjiajiensis Zhang,Gui et You,1995实际是绢蜉E．serica Eaton。1871的同物异名(新异名),湖南蜉E．hunanensis Zhang,Gui et You,1995是梧州蜉E．wuchowensis Hsu,1938的异名(新异名)。本文还报道1新种——红斑蜉Ephemera rufomaculata sp．nov．的成熟稚虫和成虫。本种成虫腹部为棕红色,腹部背板1～2节具大面积的色块,腹部3～9节背板各具3对黑色纵纹,雄性外生殖器具发达的阳端突以及阳茎端部明显向后突出而十分独特,极易与已知种区分。本种稚虫因具有与成虫相似的腹部背板斑纹以及较小的上颚突起也易识别。     

简讯

<正> 第四届国际蜉蝣学会议即将召开 今年9月4日至10日将在捷克斯洛伐克贝奇尼(Bechyne)举行第四届国际蜉蝣学会议。会议将分七个学科进行专题讨论,即分类学、系统学和高级分类学;地区分类学、生物地理学;形态学、解剖学、亚显微结构学;区系学、生态学、寄生虫学、种群力学;发育、生长、生理学;稚虫和成虫的习性、行为学;环境污染和毒理学、指示生物学等。 我国蜉蝣学者首次应邀并将准备参加这一国际学术会议。(归鸿)     

谈谈衰老

任何生物在个体发育的最后阶段,都要进入衰老。衰老是生物体在正常环境条件下,机能的进行性减退,逐渐趋向死亡的现象。凡是自然死亡,都正如恩格斯所说的“死亡不是一个突然事件,而是一个长期的过程”。同一个人,每一瞬间都处在不断的产生与衰亡之中。当然,衰老过程的长短是相对的,可塑性很大,蜉蝣成虫朝生暮死,而澳州的苏铁树已经活了一万二千多年。     

毛诗蜉蝣虫名疏证

毛诗曹风“蜉蝣之羽,衣裳楚楚。心之忧矣,于我归处。蜉蝣之翼,采采衣服。心之忧矣,于我归息。蜉蝣掘阅,麻衣如雪。心之忧矣,于我归说。”这是我国现存文献中关于蜉蝣的最早纪载,亦即后世解释这一虫名的最后根据。日本学者以此名作为Ephemeroptera(蜉蝣目)一目昆虫的名称,我国现今昆虫学上一贯沿用,这是对的。但是唐人孔颖达作毛诗正义,引用了郭璞,陆玑及樊光的说法(郭,陆,樊三人时代有先后,此处依孔颖达所引的次序)。以为蜉蝣是一种甲虫,这就在后来文献中发生了很多混乱,以致最近朱弘复高金声二位同志所著本草綱目昆虫名称注根据本草網目中资料也认为它们可能是属于金龟子科中的一种昆虫。这是必须加以辩正的。为了便于与古代文献作比较起见,兹将蜉蝣目昆虫的生活习性作一个概略的叙述。按     

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．。     

Mayfly locomotory responses to endoparasitic infection and predator presence: the effects on predator encounter rate

SUMMARY. 1. The effects of predaceous stoneflies and endoparasilism by mermithid nematodes on the locomotory behaviour of individual mayflies were studied in the laboratory. The effects of predator- and parasite-induced changes in activity on predator encounter, attack and capture rates were also examined.
2. In response to predator presence non-parasitized mayflies decreased activity, while parasitized mayflies increased activity, in comparison to a control group. As a result, the faster-moving parasitized individuals encountered stonefly predators much more frequently. The frequency of attacks per encounter did not change.
3. In view of this and other studies, two predator-avoidance strategies based on mayfly locomotory and defensive capabilities are proposed: (a) Mayflies that are able effectively to flee a predator's attack and those able to employ a behavioural defence may decrease their mean velocity when a predator is detected, thereby reducing the likelihood of an encounter while allowing foraging to continue; (b) Slower-moving or otherwise defenceless mayflies may immediately move away from the area in which a predator is perceived in order to avoid an encounter.
4. In the absence of a predator, parasitized mayflies demonstrated greatly increased activity. This probably reflects increased foraging in response to the nutritional deficit imposed by the endoparasite. A decrease in upstream movement by parasitized mayflies may also indicate a parasite-imposed energy stress.     

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.     

Habitat suitability modelling for mayflies (Ephemeroptera) in Flanders (Belgium)

Logistic regressions, artificial neural networks, support vector machines, random forests and classification trees were used to predict habitat suitability for mayflies on basis of physical–chemical water characteristics, dominant land use type and structural parameters. As a case-study, the dataset of Flanders was used, which consisted of 4289 samples containing mayflies (presences) and 3315 samples from waters where mayflies were never encountered (absences). For all techniques, data were randomly divided in a training set (two thirds) and a test set (one third). Models were calibrated using a tenfold cross-validation on the training set and subsequently validated using the test set. All techniques delivered good models that were able to discriminate sites with and without mayflies and performance (expressed as percent correctly classified instances and kappa-statistics) was in all cases similar for the training and the test set. Artificial neural networks and random forests performed slightly better compared to the other techniques. Samples with mayflies contained significantly more oxygen, a better developed river structure, higher values for sinuosity and steeper slopes, while samples without mayflies had significantly higher values for ammonium, nitrite, Kjeldahl nitrogen, total phosphorous, orthophosphate, biological and chemical oxygen demand, pH and conductivity. Also land use differed significantly, with mayflies usually present in forests but absent in industrial areas. The prevalence of mayflies gradually increased during the nineties from about 20 to 40%, which corresponded with an improvement of the chemical water quality. During the last decade, however, water quality did not further improve and as a result, mayflies prevalence did not continue to increase. Based on the planned measures, an ensemble forecast using the five mentioned modelling techniques predicted that mayflies prevalence will increase to 46% by 2015 and to 72% by 2027. To meet the requirements of the European Water Framework Directive, which states that all surface waters should obtain a good ecological quality, extra efforts will be needed to decrease nutrient concentrations and to improve habitat quality.     

Bridges as optical barriers and population disruptors for the mayfly <Emphasis Type="Italic">Palingenia longicauda</Emphasis>: an overlooked threat to freshwater biodiversity?

Freshwater biodiversity is declining faster than marine or terrestrial diversity, yet its drivers are much less known. Although dams were shown to negatively affect river habitats, fragmentation by bridges has received less attention and is not as well understood. We tested whether and how bridges present barriers to aquatic insects by studying mass swarmings of Palingenia longicauda mayflies on river Tisza (NE-Hungary). Behavioural observations showed that upon approaching the bridge, upstream-flying mayflies typically turned back and 86% of them never crossed the bridge. Lack of physical contact showed that the bridge was an optical, rather than a mechanical barrier for the polarotactic mayflies. Imaging polarimetry showed that the bridge disrupted the horizontally polarizing channel guiding the flight of mayflies above the river. Energy loss, demonstrated by calorimetry, and time constraints forced females to lay eggs only downstream from the bridge. Counts of larval skins shed by swarming individuals showed nearly 2 to 1 female per male downstream from the bridge, while sex ratio above the bridge was slightly male-biased. We suggest that the surplus of parthenogenetic females, that produce only female larvae, downstream from the bridge may have led to the observed sex-ratio bias since the construction of the bridge (1942). Our results demonstrate that bridges can be optical barriers for aquatic insects and can cause population-level impacts, such as biased sex ratios, in natural populations. Sex ratio biases due to bridges may decrease effective population size and genetic variability, which may have contributed to the recent extinction of this species from most of Europe.     

Diel feeding periodicity, daily ration and prey selection of a riverine population of juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum)

The diel feeding periodicity, daily ration and prey selection of juvenile chinook salmon, Oncorhynchus tshawytscha , were studied in relation to the available prey. Maximum dry weight of food intake occurred about dawn, when mayflies were the major prey, but the greatest number of freshly eaten prey occurred during the afternoon, when chironomids and terrestrial dipterans predominated. Feeding activity at night was low, with smaller mayflies comprising up to 50% of the prey. During the day the young salmon fed selectively on chironomids and the larger mayflies, while trichopterans and terrestrial taxa were under-represented in the diet. Food consumption over the 24-h period averaged 8.3% of the fish dry body weight. Prey abundance in the drift explained about 50% of the composition of the diet. Although the fish selected larger mayflies, size apparently was not a main criterion for selection because chironomids, although smaller than mayflies, were also frequently eaten. Previous dietary experience of the fish and the diel pattern of prey abundance appear to best explain the selective feeding of juvenile chinook salmon.     

Flightlessness in mayflies and its relevance to hypotheses on the origin of insect flight

Until now, only fully winged mayflies have been known. It has been proposed recently that brachyptery could be a missing link in the development of insect flight, via sailing or skimming aquatic insects. To our knowledge, we report here the first documented case of brachyptery in mayflies. The flightless genus Cheirogenesia is endemic to Madagascar, and the adults skim the water surface. This loss of the flight function has induced important physiological changes, such as a shift from lipids to carbohydrates in the energy reserves used during their adult life. Comparison of wing area of living mayflies with fossil species indicates that brachyptery could have already occurred in early flying insects (in the Permian). We argue that flight loss in Cheirogenesia has been made possible by the lack of fish predation in its natural habitats.     

The influence of upstream predation on the expression of fish effects in downstream patches

1. Enclosures were installed in a fishless stream and divided transversely into upstream and downstream sections. Downstream sections were further divided longitudinally, and one of the downstream sections in each enclosure was stocked with juvenile coho salmon ( Oncorhynchus kisutch ), and the other side was left as a fishless control. Densities of juvenile coho were then manipulated in upper sections of enclosures to determine the effect of upstream predation intensity on fish predation effects in downstream sections.
2. Significantly fewer mayflies (primarily Ameletus sp.) were observed grazing on unglazed ceramic tiles in lower enclosure sections with fish present. There was no detectable effect of fish density in upstream enclosure sections on the number of mayflies observed grazing on ceramic tiles in lower sections of the enclosures.
3. There was a significant positive effect of both fish presence and upstream density on chlorophyll a concentrations on ceramic tiles in lower enclosure sections, but not on chlorophyll a on natural gravel substratum.
4. Behavioural experiments with mayflies and coho in streamside troughs suggest that Ameletus sp. responds primarily to mechanical rather than chemical cues from coho parr.     

Differential behavioural responses of mayflies from streams with and without fish to trout odour

1. In streams, mayflies (Order Ephemeroptera) are at risk from fish feeding visually in the water column. The effect of fish odour on the behaviour of Baetis bicaudatus from a fishless stream and a trout stream was investigated in four large oval tanks supplied with water from the fishless stream.
2. For each mayfly population, mayfly positioning on the substratum and movement in the water column (drift) were measured during the day and night, over 3 days. Brook trout ( Salvelinus fontinalis ) odour was added to two tanks to test the effect of a threat from fish.
3. Throughout the experiment more mayflies from the trout stream were observed on the substratum surface and in the water column during the night than the day, but the magnitude of night drift was less in tanks with fish odour.
4. Baetis from the fishless stream also displayed a nocturnal periodicity in drift and positioning, but their night-time drift was not affected by the presence of fish odour. On the first day of the experiment, however, more mayflies were observed on the substratum surface and drifting in tanks without fish odour during the day.
5. Sensitivity to fish odour may enable mayflies to alter their behaviour according to the risk of predation from fish.     

Differential behavioural responses of mayflies from streams with and without fish to trout odour

1. In streams, mayflies (Order Ephemeroptera) are at risk from fish feeding visually in the water column. The effect of fish odour on the behaviour of Baetis bicaudatus from a fishless stream and a trout stream was investigated in four large oval tanks supplied with water from the fishless stream.
2. For each mayfly population, mayfly positioning on the substratum and movement in the water column (drift) were measured during the day and night, over 3 days. Brook trout ( Salvelinus fontinalis ) odour was added to two tanks to test the effect of a threat from fish.
3. Throughout the experiment more mayflies from the trout stream were observed on the substratum surface and in the water column during the night than the day, but the magnitude of night drift was less in tanks with fish odour.
4. Baetis from the fishless stream also displayed a nocturnal periodicity in drift and positioning, but their night-time drift was not affected by the presence of fish odour. On the first day of the experiment, however, more mayflies were observed on the substratum surface and drifting in tanks without fish odour during the day.
5. Sensitivity to fish odour may enable mayflies to alter their behaviour according to the risk of predation from fish.     

How can Asphalt Roads Extend the Range of In Situ Polarized Light Pollution? A Complex Ecological Trap of <Emphasis Type="Italic">Ephemera danica</Emphasis> and a Possible Remedy

When an artificial surface (e.g. an asphalt road) reflects strongly and horizontally polarized light as water bodies do in the nature, polarotactic aquatic insects, like the creek-dwelling Ephemera danica mayflies easily become deceived. After swarming above the creek surface, E. danica females begin their upstream compensatory flight and can be deflected at bridges with an asphalt road and continue their flight above the road surface. Thus, the water-mimicking optical signal of the road may deceive water-seeking polarotactic mayflies and lead them to distant, polarized-light-polluting surfaces, which elicit anomalous oviposition. On an asphalt road crossing a creek, we deployed polarizing insect traps at different distances from the bridge. The traps captured E. danica mayflies and their catch numbers indicated that these mayflies originated from the direction of the bridge, proving that they followed the track of the road. Our results suggest that distant polarized-light-polluting objects along an asphalt road can trap mayflies emerging from a creek crossing the road. The combination of an asphalt road and a man-made in situ (local) polarizing surface forms a complex ecological trap, being capable of luring aquatic insects from greater distances. To eliminate the oviposition of dangered polarotactic aquatic insects emerging from a creek onto the asphalt road crossing the creek, we suggest to deploy strongly and horizontally polarizing water-filled black trays along the edge of the road during the swarming period. Thus, the eggs of the deceived insects can be moved back to the creek in order to assist the conservation of the offspring-generation.