Emergence pattern,microhabitat choice,and population structure of the Maghribian endemic Gomphus lucasii Selys, 1849 (Odonata: Gomphidae) in northeastern Algeria

Emergence of Gomphus lucasii Selys, 1849, an unstudied Maghreb endemic, was synchronised by overwintering in the final stadium in the Seybouse River in northeastern Algeria. Regular collections revealed that half of the annual population emerged during 10 days, showing a typical ‘spring species’ emergence pattern. Sex ratio was slightly male biased (51%). Males and females did not differ in vertical stratification. Emergence support choice was not random, but rather depended on support height, body size, and daily population density. Mortality was caused mainly by ants, although deformity of tenerals and bird predation were also important factors. Gomphus lucasii has been assessed as vulnerable (International Union for Conservation of Nature (IUCN) Red List), and the information provided in our study will be helpful in future conservation efforts.     

Distribution Patterns and Habitat Characterization of Elmidae and Hydraenidae (Insecta: Coleoptera) in the Weidlingbach Near Vienna,Austria

A total of 870 adult and 831 larval Elmidae and Hydraenidae were caught from September 1995 to September 1996 at the Weidlingbach, a fourth order tributary of the Danube near Vienna, Austria, using a Heß sampler at 14 sampling stations from source to mouth. Elmis maugetii (Latreille ) and Riolus subviolaceus (Müller ) accounted for 66.3% of the total, whereas Hydraena gracilis (Germar ) was the most abundant Hydraenidae species. Based on head width, instars 1–6 were collected in E. maugetii, instars 2–6 in R. subviolaceus and instars 3–6 in Limnius volckmari (Panzer ) and Riolus cupreus (Müller ); from the remaining species, only instars 4–6 were sampled. E. maugetii was most abundant on coarse, moss-covered substrates (median = 22.2 mm) exposed to high water velocity (median = 69.4 cm/s; range = 6.0–117.6 cm/s); the latter was also true for R. subviolaceus although it favoured smaller sediment grain sizes (median = 10.7 mm). Sites exposed to only moderate flow and with abundant filiform algae were preferred by Esolus parallelepipedus (Müller ) and L. volckmari, whereas the Hydraenidae species, Esolus angustatus (Müller ), R. cupreus and Oulimnius tuberculatus (Müller ) were collected mostly at sites with moderate current speed and abundant moss-covered pebbles of various size. Species richness and population density increased from source to mouth. At the spring sampling site Elmidae and Hydraenidae were completely lacking.     

Spatial and temporal abundance,substrate partitioning and species co-occurrence in a guild of Neotropical blackflies (Diptera: Simuliidae)

Blackfly larvae were sampled monthly from two smallNeotropical mountain streams 500 m apart from each other in northernVenezuela during a 15-month period, and ten habitat variables weremeasured at two altitudes (800 and 900 m) to determine local spatialand temporal variations in abundance, stream variables, speciesco-occurrence, and substrate preference within the blackflyguild. The blackfly species composition of each stream was the same,with five species (in order of abundance): Simulium ochraceumWalker s.l., S. paynei Vargas, S. metallicum Bellardicytospecies E, Simulium sp., and S. horacioi Okazawa &Onishi. There were clear differences in community structurebetween streams (not among altitudes), although S. ochraceums.l. was the most abundant species in both habitats. Principal component andcorrelation analyses revealed that structural (great depth, width,flow, and discharge) and chemical (low conductivity) factors werethe stream variables best associated to the spatial distribution ofmost blackfly species. Blackfly abundance was greater in the largerstream. Larvae were most abundant on submerged rocks and fallenleaves, although the patterns of substrate use within the guildrevealed substrate partitioning among most blackfly species.There was one general annual peak of abundance at the end of therainy season. We suggest that blackfly community structure in theseNeotropical headwaters streams, over the small spatial scaleexamined here, is largely influenced by interactions among streamsize and velocity-related factors (width, streamflow, discharge andsubstrate availability-stability) and the rainfall regime.     

番茄潜叶蛾幼虫和卵在新疆大棚番茄的空间分布型及理论抽样数

【目的】明确新疆新发外来入侵生物番茄潜叶蛾幼虫和卵在不同种群密度下的垂直分布、空间分布型和理论抽样数,探索田间易观察的危害症状和幼虫密度的关系,为田间取样和调查提供理论指导。【方法】在察布查尔县连续调查3个大棚同一品种京番502杂交一代上的番茄潜叶蛾的不同种群密度,利用聚集度指标及Iwao回归分析,计算并分析了番茄潜叶蛾卵和幼虫在不同种群密度下的空间分布型、垂直分布和理论抽样数,分析危害叶片数、虫道长度和虫道数与幼虫密度的动态关系。【结果】计算并统计番茄潜叶蛾幼虫和卵的空间分布聚集度指标的均值m、扩散系数C、扩散型指数I、负二项分布值K、平均拥挤度m~*、聚块指数m~*/m、扩散指数CA和种群聚集均数λ。番茄潜叶蛾卵主要集中在上部,占比43.9%～100%。幼虫主要集中在下部,占比53.3%～100%。番茄潜叶蛾幼虫数与虫道数、虫道长度或为害叶片数的比值随为害加剧呈动态变化。番茄潜叶蛾幼虫和卵Iwao直线回归方程拟合公式为m~*=1.9114+1.2055m (R~2=0.9703)和m~*=0.0536+1.4147m (R~2=0.9014)。根据空间分布型参数,在D=0.1、0. 2和0. 3时,幼虫的理论抽样数模型分别为n=1118. 4/x+78. 9、n=279. 6/x+19.7、n=124.3/x+8.8,卵的理论抽样数模型分别为n=404.8/x+159.3、n=101.2/x+39.8、n=45.0/x+17.7,该模型适用于不同虫口密度下的田间抽样。【结论】在京番502杂交一代上,番茄潜叶蛾幼虫为m=0.6头·株~(-1)以上,卵在达到密度最大值前,均呈聚集性分布。番茄潜叶蛾成虫偏好在幼嫩的叶片产卵,随植株被害加剧该偏好略有减弱。当番茄潜叶蛾幼虫的虫口密度为10和30头·株~(-1)时,建议分别取样50和30株;当卵量为10和30粒·株~(-1)时,分别取样50和45株。     

西花蓟马在黄瓜和架豆上的空间分布型及理论抽样数

西花蓟马Frankliniella occidentalis（Pergande）已在北京部分蔬菜园区成功定居,对蔬菜生产造成危害。为了解该虫在蔬菜田的种群空间分布型,指导田间取样,本文应用几种聚集度指标的计算公式以及Taylor、Iwao的回归方程式,分析和测定了西花蓟马的种群空间分布格局。结果表明：在黄瓜和架豆上西花蓟马的空间分布型一致,均为聚集分布型;该虫的空间分布型不受种群密度的影响,并且也不随取样时间的变化而变化。种群数量动态研究显示西花蓟马成虫和若虫在黄瓜植株的中部叶片分布较多（从顶部向下数第4叶至第17叶片上成、若虫的分布数量多于其他叶片上的数量）,未展开的叶片、嫩叶和下部老叶危害较轻。用Iwao回归法中α、β参数计算出在允许误差范围内的理论抽样数。     

桑蓟马在桑树中空间分布的研究

桑蓟马Pseudodendrothrips mori是桑树的一种主要害虫。它的寄生直接影响供桑叶的质量和产量。我们通过泰勒幂法则和Morisita的散度指标对桑树蓟马在植株和桑园内的空间分布进行检验,结果显示:P.mori种群在植株内和桑园里的分布都存在局部化。桑树中蓟马的分布在树内显示出幼虫蓟马位于低层(从上面叶子起5-10层),但成虫更喜欢上层(从上面叶子起1-5层)。同一植株叶子的不同方向上蓟马密度没有出现明显变化。桑园内蓟马主要分布在桑园东部、南部和北部的植株上,中部,西部植株上的蓟马密度较低。P.mori的成虫和幼虫在叶子上的分布呈现明显聚集化。     

Genetic homogeneity of the Sedgling Nehalennia speciosa (Odonata: Coenagrionidae) indicates a single Würm glacial refugium and trans‐Palaearctic postglacial expansion

The phylogeographic structures of taiga species often support the hypothesis of East Palaearctic refugia for these taxa, but the phylogeographic structures of northern temperate and southern boreal bog species are still poorly understood. Therefore, we analysed the genetic diversity and differentiation of a stenotopic damselfly, Nehalennia speciosa, across its trans‐Palaearctic range by means of sequencing two mitochondrial gene fragments, 16S rRNA‐ND1 and cytochrome c oxidase II. Only four single nucleotide polymorphisms were detected over the 1130 sequenced nucleotides. This low genetic diversity and differentiation and thus the lack of phylogeographic structure imply postglacial expansion from a single Würm Ice Age refugium, most likely located in the Far East of Asia, i.e. Manchurian refugium. From here, the species could have colonized large parts of the Palaearctics, including Europe, during the postglacial.     

Spatial Distribution of the Nematode Fauna and Production of Three Nematodes (Tobrilus gracilis,Monhystera stagnalis,Ethmolaimus pratensis) in the Profundal of Piburger See (Austria, 913 m a.s.l)

The species composition and the spatial distribution of the nematode fauna of Piburger See is discussed briefly. The study then concentrates on the three species (Tobrilus gracilis, Monhystera stagnalis, Ethmolaimus pratensis) which form the lake's profundal nematode fauna between depths of roughly 8 and 13 meters. This profundal fauna is separated by a distinct metalimnetic abundance minimum from the very diverse littoral community. In addition to taxonomic and ecological considerations, the zonation of the three species within their main habitat is described, and life cycles cohort production as well as annual production are evaluated from the field data. Total annual nematode production within the profundal habitat (8–13 m) in Piburger See amounts to 11.6 kg per hectare. 65 % of which are contributed by T. gracilis, 22 % by M. stagnalis and 13 % by E. pratensis. For the whole area under observation (6 to 13.5 m, including the scarcely populated border zones) mean annual nematode production is 7 kg per hectare.     

Distribution and population dynamics of ostracodes (Crustacea,Ostracoda) in a karstic lake: Lake Banyoles (Catalonia,Spain)

Qualitative and quantitative benthic samples were collected monthly between December 1986 and December 1987 from several stations at various depths and basins in the karstic Lake Banyoles (Catalonia, Spain), to study the spatial distribution and seasonality of ostracodes. A total of eight ostracode species were found in the lake. Of these, Candona neglecta Sars, Isocypris beauchampi Paris and Cypria ophtalmica Jurine were the most common ostracodes at all depth stations. Darwinula stevensoni Brady & Robertson, Ilyocypris species (I. bradyi Sars and I. gibba (Ramdohr)), Cyprideis torosa (Jones) and Cyclocypris ovum Jurine, on the other hand, were confined to sublittoral and littoral areas of the lake.Substrate and organic matter content appeared to be relevant factors determining the distribution of ostracode species at the different stations. The highest abundance of ostracodes were in the sublittoral (Basin IV–7 m and Basin I-5 m) where the substrate was coarse and sediment had a high organic matter content (>35% LOI). Low oxygen levels in the hypolimnetic waters (i.e. < 1 mg l^–1) may explain the absence of ostracodes at deeper zones in stations where the anoxic period lasts more than four months. On the other hand, low temperatures seem to favour the development of C. neglecta and D. stevensoni, while with higher temperatures I. beauchampi, C. torosa and C. ovum increased their abundances. However, no clear pattern can be observed, so ostracode species in Lake Banyoles, apparently, have non-seasonal life histories.     

The Reaction of Mytilus trossulus Larvae (Bivalvia,Mytilidae) to Desalination and Increase of Water Column Temperature

Under homogeneous salinity and temperature conditions and uniform daylight, the early larvae of the Pacific mussel Mytilus trossulus (blastulae and trochophores) accumulated in the uppermost layer of water column, while the late larvae tend to concentrate at the bottom. In a water column with a temperature or salinity gradient, the early larvae accumulated at the surface even when the salinity and temperature conditions were incompatible with their life activity. The distribution of the late larvae was different as they were able to leave water of unfavorable temperature and salinity and accumulate at the bottom.     

Southeastern Pacific humpback whales (Megaptera novaeangliae) and their breeding grounds: Distribution and habitat preference of singers and social groups off the coast of Ecuador

Understanding the distribution, habitat preference, and social structure of highly migratory species at important life history stages (e.g., breeding and calving) is essential for conservation efforts. We investigated the spatial distribution and habitat preference of humpback whale social groups and singers, in relation to depth categories (<20 m, 20–50 m, and >50 m) and substrate type (muddy and mixed) on a coastal southeastern Pacific breeding ground. One hundred and forty‐three acoustic stations and 304 visual sightings were made at the breeding ground off the coast of Esmeraldas, Ecuador. Spatial autocorrelation analysis suggested singers were not randomly distributed, and Neu's method and Monte Carlo simulations indicated that singers frequented depths of <20 m and mixed substrate. Singletons, and groups with a calf displayed a preference for shallower waters (0–20 m), while pairs and groups with a calf primarily inhabited mixed bottom substrates. In contrast, competitive groups showed no clear habitat preference and exhibited social segregation from other whales. Understanding the habitat preference and distribution of humpback whales on breeding and calving grounds vulnerable to anthropogenic disturbance provides important baseline information that should be incorporated into conservation efforts at a regional scale.     

Effects of Predation Risk and Food Availability on the Activity,Habitat Use,Feeding Behavior and Mating Behavior of a Pond Water Strider,Gerris marginatus (Hemiptera)

By experimentally manipulating predation risk and food availability, we explored the effects of these factors on refuge use, general activity, feeding activity, and mating activity of adults of the pond water strider Gerris marginatus. Predation risk (from adult backswimmers Notonecta undulata) profoundly influenced the behavior of G. marginatus, reducing mating activity, general activity in males and females, decreasing feeding activity in females and increasing the use of refuge by both sexes. Surprisingly, variations in food availability failed to produce significant effects on any of these behavior patterns. Risk x food interactions were also not statistically significant for any gerrid behavior. The significant responses to predators all changed in directions that should decrease the risk of predation for G. marginatus.     

云南元江芒果园桔小实蝇成虫日活动规律及空间分布格局

利用甲基丁香酚引诱剂和黄板对桔小实蝇Bactrocera dorsalis成虫日活动规律及飞行高度进行了研究,同时根据多种聚集度指标对桔小实蝇成虫的空间分布格局进行了分析。结果表明:元江县挂果期芒果园内桔小实蝇日活动量高峰出现在10:00、16:00左右,活动量低谷出现在8:00、14:00和19:00左右,日间温湿度与其日活动量之间无线性相关关系;成虫飞行高度随时间变化,受降雨影响,雌雄成虫飞行高度存在差异。上午、中午成虫多近地飞行,午后多在1.5 m以上高度飞行,降雨导致成虫飞行活动量大幅减退,多分布于1.5 m以上枝叶附近。株高8 m的3a芒果树4 m高度处黄板捕获虫量最大,其次是2 m高处,6m以上虫量较少。雄性成虫在芒果园中呈聚集分布,原因之一是其自身的聚集行为;雌虫空间分布不均,主要呈聚集分布,少数部分为均匀分布,其聚集由环境因素造成。     

Day‐Night Vertical Distribution and Feeding Patterns of Fourth Instar ofChaoborus Larvae in a Neotropical Reservoir (Socuy Reservoir,Venezuela)

The day‐night vertical distribution, diel feeding activity and diet of fourth instar of Chaoborus larvae were analyzed in lacustrine zone of a neotropical reservoir which shows seasonally contrasting hypolimnetic oxygen conditions. Larvae stayed in sediment and water bottom during day and ascended to surface during night. Results indicate that feeding activity is limited mainly to the plankton population. Phytoplankton, rotifers or remains of Chaoborus larvae were not found in crops. With the exception of ostracods, all crustacean prey available in the zooplankton occurred in the guts. Ceriodaphnia cornuta and Moina micrura were the most frequent food items (about 75% of occurrence frequency) and were positively selected. The remainder crustacean zooplankton taxa were negatively selected by larvae. The most intense feeding activity in larvae occurred near midnight and sunrise, in dates when the hypolimnion was anoxic. When oxygen was available on the bottom, a higher and not changing diel feeding activity was detected. Our results indicate that vertical migration may promote a spatial separation between larvae and zooplankton, and feeding activity of larvae occurred only when both overlapped. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Horizontal and vertical distribution of saproxylic beetles (Col., Buprestidae, Cerambycidae, Scolytinae) across sections of forest edges

Abstract:  We evaluated the preferred home ranges of three saproxylic beetle taxa along transects from the open field into the forest interior, and from the forest floor up to the canopy. By means of trap sets on metal scaffolds, vertical and horizontal strata were sampled across two types of forest edges: soft-edge ecotones with a gradual transition from the field into the forest and hard edges with an abrupt transition. The forest edges consisted of different strata such as herbaceous fringe, shrub belt, unmanaged forest and managed forest. The thermophilic buprestids were mainly caught in the open land (herbaceous fringe and agricultural land) and in the upper forest mantle. In general, the cerambycids were most abundant in the open land and the lower forest mantle, but a few species favoured the forest interior. The bark beetles (Scolytinae) were equally distributed in all habitats. These distribution patterns of the taxa were observed in terms of both species numbers and abundances. Each species with at least five collected specimens was assigned to one of the three habitat types: open land, forest mantle and forest interior. Of 74 ranked species, only 16% were prevalent in the forest interior and are thus considered to be true forest species. The other 84% of the species were attributed to open land or the forest mantle and are, therefore, forest edge species. Soft forest edges generally supported a higher species richness than hard edges, particularly as regards Cerambycidae and Scolytinae. In terms of Shannon diversity, soft edges tended to be more diverse in buprestids and cerambycids. Overall, the forest interior showed the least species richness and diversity. Therefore, for the conservation of saproxylic beetles, not only the amount and quality of dead wood is important, but also the presence and design of forest boundary structures.     

Life History Studies on the Genus Trillium (Liliaceae) IV. Stage Class Structures and Spatial Distribution of Four Japanese Species

Abstract The population struaures, spatial and temporal distributions of individual plants, and survivorship were investigated in four Japanese Trillium species (Liliaceae), T. kamtschaticum, T. tschonoskii, T. apetaion and T. smallii.
The stage class structures of these four species based on leaf area categories all showed similar depletion curves associated with an increase in stnge class. That is, there occurs a conspicuous decrease in early juvenile stages, subsequent leveling-off in the intermediate stages and a slight decrease again in the larger stages. The high mortality in juvenile stages was also confirmed by continuous observations in the permanent plots established on the forest floor for T. kamtschaticum and T. apetalon. Furthermore, the analysis of spatial distribution patterns for T. kamtschaticum and T. apetalon revealed successive distributional changes from under-dispersed (aggregated) to random or overdispersed with the progress of the growth stage.     

Distribution Patterns,Species Assemblages and Habitat Selection of the Stoneflies (Plecoptera) from Two Mediterranean River Basins in Southern Spain

The stonefly distribution and its relationship with habitat changes, based on stream physico chemical features, were investigated in two Mediterranean river basins (Guadaira and Guadalete, S Spain). Plecopteran nymph distribution varied along an elevation gradient. Both stonefly species richness and species diversity increased with altitude. Stoneflies were able to tolerate a wide range of environmental conditions but were absent from low altitude sites, temporary streams with high salinity values and high water temperature. A total of 13 stonefly species were found in the study area, from which Tyrrhenoleuctra minuta (Klapálek ) and Protonemura sp. were dominant. The most widespread species were Nemoura lacustris and Capnioneura mitis. Three distinct species assemblages were observed according to their distribution patterns, but with similar environmental preferences. Capnioneura petitpierreae and T. minuta showed preferences to low altitude sites, whereas C. mitis and N. lacustris were found throughout all sites. T. minuta and N. lacustris inhabited permanent and temporary sites, while the same species and C. mitis also were found in semipermanent streams. Temporally, most stoneflies were caught during winter (85.9%), especially at the low altitude sites.     

Food Preference of Perch (Perca fluviatilis) Stocked in a Previously Fishless,Acid Bog Lake and Development of the Fish Population in Absence of Piscivory

The almost fishless, acid Lake Fuchskuhle was physically partitioned into 4 sections and stocked with young, 10‐ to 13‐cm perch. Their body growth was normal only up to age 4 years. Although the perch spawned successfully, reproduction was negligible because only few offspring survived the first year of life. Food for young perch was plentiful, benthic invertebrates composing the main source. Because the population included only 2 to 3 year classes, the perch could not shift from benthic feeding to piscivory as they grew. As a result, growth rate decreased in older fishes (over 4–5 years old). The benthic food supply alone could not satisfy the energy requirements of the older perch.     

Distribution,Abundance and Life Cycles of Oligochaeta from the Marine Hygropsammal with Special Reference to the Phallodrilinae (Tubificidae)

Tubificid and enchytraeid oligochaetes are common members of the interstitial fauna of sandy beaches. Their abundance dynamics, life cycles and distribution patterns were investigated at two beaches on the western Baltic Sea and at a North Sea beach (Isle of Sylt). Populations of 115,000 ind./m² were found at protected Baltic beaches. Reproduction of the tubificids, Phallodrilus monospermathecus and Spiridion insigne takes place within a well defined breeding period once a year. The market horizontal and vertical distribution patterns of various tubificid and enchytraeid species are elucidated by preference reactions to several physiographic parameters, such as oxygen and water content of the sediment, and salinity.     

世界砂藓属植物地理分布格局及其系统演化意义

以“Index Muscorum”中的20个藓类植物地理分布单位为分析区域,基于标本信息和相关文献,统计了世界砂藓属84种植物在20个地理单位的分布数据,应用除趋势对应分析法和三维空间图直观地展示了世界砂藓属植物的地理分布格局。发现世界砂藓属植物分布明显地分为南半球区和北半球区,并与岗瓦纳古陆和劳亚古陆有较好的对应性。南半球区包括Am.2,Am.3,Am.4,Am.5,Am.6,Afr.2,Afr.3,Afr.4,Austr.1,Austr.2,As.4和Ant.等12个地理单位;北半球区包括Am.1,Eur.,As.1,As.2,As.3,As.5,Afr.1和Oc.等8个地理单位。砂藓属中的无瘤类群在南、北半球分布广泛,而叶片细胞壁具瘤的Niphotrichum和Codriophorus亚属的种类主要分布在北半球。推测砂藓属植物的起源应早于联合古陆分裂以前,其祖先类群的叶片细胞表面光滑无瘤。