A diver-operated quantitative bottom sampler for sand macrofaunas

Summary 1. A new bottom sampler for macrofauna is described which is easily operated by a diver.2. The airlift pump principle is employed firstly to sink a sampling cylinder into the seabed and secondly to operate a suction pipe which is used to excavate sand and animals from within the cylinder.3. The sampler covers an area of 0.1 m² and penetrates to a depth of 60 cm. It is particularly suitable for quantitative studies of deeper burrowing fauna (e. g.Ensis spp. andLutraria spp.).4. The sampler is designed for use in sandy sediments and for studies on the distribution of faunas within small areas where line transects or grids of samples are required.

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Ein vom Taucher betätigtes Gerät zur quantitativen Entnahme der Makrofauna auf Sandböden

Kurzfassung Zur Entnahme quantitativer Proben der Makrofauna aus festem Sandboden gibt es nur zwei Geräte, die beide sehr schwer sind und einer kräftigen Winde auf einem großen Schiff bedürfen: (a) der Knudsengreifer (0,1 m² Fläche, 30 cm Einstichtiefe, 150 kg) und (b) der Kastengreifer von Reineck (20×30 cm Fläche, 40 cm Einstichtiefe, 750 kg). Für Untersuchungen über die Verteilung benthischer Makrofauna innerhalb kleiner Gebiete war jedoch ein Gerät zur Entnahme von Bodenproben erwünscht, das von einem Taucher gezielt eingesetzt werden kann. Eine Sammeltiefe von mehr als 30 beziehungsweise 40 cm war erforderlich, um den Fang der tiefer grabenden Arten, beispielsweise der MuschelLutraria, zu gewährleisten. Das neue Gerät wurde zweiteilig entworfen. Der eine Teil besteht aus einem offenen Stahlzylinder, der eine Länge von 60 cm und eine Grundfläche von 0,1 m² aufweist. Er wird zunächst mit Handkraft senkrecht in den Boden hineingepreßt, damit er vom Sand gut abgedichtet wird. Das obere Ende wird anschließend mit einem Deckel verschlossen, und das Wasser, das sich im Zylinder oberhalb des Sedimentes befindet, wird durch eine Pumpe abgesogen. Der hydrostatische Druck auf den Deckel preßt den Zylinder in den Sand. Wenn der Zylinder völlig in das Sediment versenkt ist, wird der Deckel entfernt und der vom Zylinder umfaßte Sand durch den zweiten Teil des Gerätes ausgesaugt. Dieser besteht aus einer langen Kunststoffröhre von etwa 8 bis 10 cm Durchmesser. Sie wird in senkrechter Stellung völlig unter Wasser gehalten. Wird Luft unter Druck in das untere Ende eingeleitet, so funktioniert die Röhre als eine Lufthebepumpe. Ein speziell gebautes Sieb ist am oberen Ende des Steigrohres befestigt. Der Taucher führt das untere Ende dieser Saugpumpe in den Zylinder und saugt dessen Inhalt in das Sieb hinein. Die Druckluft für die Betätigung des Instrumentes wird von einem Kompressor oder aus Druckluftflaschen (4–5 m³) geliefert. Das beschriebene Gerät ist leicht und kann deshalb mühelos vom Taucher bedient werden. Es kann von Kleinbooten aus eingesetzt werden und benötigt keine Winde.

     

An efficient and quantitative aquatic benthos sampler for use in diverse habitats with variable flow regimes

A suction sampler designed to minimize sampling error, and quantitatively collect benthic macroinvertebrates from coarse substrata under various flow regimes is described. This sampler uses a 12 V bilge pump (capacity 4400 1 h^–1) to suck animals into a collecting net from substrata disturbed by a single operator. Macroinvertebrates were collected more rapidly by this sampler than by a Surber sampler or a Boulton suction sampler. Sources of sampling error are discussed for all three samplers. The electric pump sampler described here is suitable for sampling habitats where depth and velocity vary spatially and with time.     

A new sampler for stream benthos, epiphytic macrofauna and aquatic macrophytes

SUMMARY. A new sampler is described combining the advantages of both box and Surber samplers. The sample area is 200 × 250 mm (0.05 m²) and the device has been used to sample the benthos of rivers to a depth of c . 60 mm where the substratum consists of particles with diameters of 50 mm or less. The basic design may be used in water up to 0.5 m in depth, but with an optional top unit this depth may be increased to 1 m. Aquatic macrophytes can also be sampled either on their own or together with the underlying substratum. Results from sampling programmes designed to estimate macrophyte biomass, the biomass of the macroinvertebrate community and the density of Gammarus pulex are given as examples of the flexibility of the sampler on a variety of biotopes.     

A quantitative sampler for collecting invertebrates associated with deep submerged vegetation

Only few of the numerous samplers for collecting invertebrate fauna associated with vegetation permit sampling at depths of more than approximately 0.5 m. This paper describes a sampler allowing collection of epifauna from submerged plants at a depth of up to approximately 2 m, growing in varied densities. The sampler is composed of two panels made of duralumin, connected on one side by means of piano-hinges. One of the panels has an opening covered with mesh, and the other is equipped with a cone-shaped net and detachable sample concentrator at its end. The sampler is coupled with a manipulator with a several meter extension for lowering the sampler under water, as well as for its opening, and closing. The initial assessment of the sampler efficiency, verified in beds of Potamogeton perfoliatus, provided similar results as two other, older and commonly used samplers. In comparison with the older devices, the sampler has the advantage of permitting collecting samples from greater depths. It also enables studying both the vertical and horizontal distribution of invertebrates within a plant patch.     

水生昆虫

介绍了水生昆虫适应水生的生物学特征,环境转换与昆虫的适应,生态类型和意义。     

Inland dispersal of adult aquatic insects

1. Adult caddisflies (Trichoptera) and mayflies (Ephemeroptera) were light-trapped on summer evenings along the Detroit River and Lake St. Clair, near Windsor, Ontario, Canada. Light traps were located at the shore and at increasing distances inland up to 5 km, and were operated simultaneously for 2 h following sunset. Catches of five species of caddisflies of the family Hydropsychidae ( Cheumatopsyche campyla , Cheumatopsyche speciosa , Hydropsyche hageni , Hydropsyche phalerata , Macrostemum zebratum ) and the mayfly Hexagenia (Ephemeridae) were used to examine inland distribution.
2. Inland dispersal was limited: catches of caddisflies declined at a greater than exponential rate with increasing distance from shore. Mean dispersal distance from the shoreline ranged from 650 to 1845 m. Smaller caddisfly species dispersed shorter distances than larger caddisflies and Hexagenia .
3. Inland distribution of adult caddisflies exhibited considerable interspecific variation: distribution was inconsistent among trials for Hexagenia , possibly owing to timing of collections in relation to periods of peak emergence.
4. Sex ratios of caddisflies were female biased at most sites. No consistent bias was observed for Hexagenia . Different inland distribution patterns were observed for males and females. The differences appeared to reflect species-specific reproductive strategies.     

Incidence of Wolbachia in aquatic insects

Wolbachia is a genus of intracellular bacteria typically found within the reproductive systems of insects that manipulates those systems of their hosts. While current estimates of Wolbachia incidence suggest that it infects approximately half of all arthropod species, these estimates are based almost entirely on terrestrial insects. No systematic survey of Wolbachia in aquatic insects has been performed. To estimate Wolbachia incidence among aquatic insect species, we combined field‐collected samples from the Missouri River (251 samples from 58 species) with a global database from previously published surveys. The final database contained 5,598 samples of 2,687 total species (228 aquatic and 2,459 terrestrial). We estimate that 52% (95% CrIs: 44%–60%) of aquatic insect species carry Wolbachia, compared to 60% (58%–63%) of terrestrial insects. Among aquatic insects, infected orders included Odonata, Coleoptera, Trichoptera, Ephemeroptera, Diptera, Hemiptera, and Plecoptera. Incidence was highest within aquatic Diptera and Hemiptera (69%), Odonata (50%), and Coleoptera (53%), and was lowest within Ephemeroptera (13%). These results indicate that Wolbachia is common among aquatic insects, but incidence varies widely across orders and is especially uncertain in those orders with low sample sizes such as Ephemeroptera, Plecoptera, and Trichoptera.     

Inland dispersal of adult aquatic insects

1. Adult caddisflies (Trichoptera) and mayflies (Ephemeroptera) were light-trapped on summer evenings along the Detroit River and Lake St. Clair, near Windsor, Ontario, Canada. Light traps were located at the shore and at increasing distances inland up to 5 km, and were operated simultaneously for 2 h following sunset. Catches of five species of caddisflies of the family Hydropsychidae ( Cheumatopsyche campyla , Cheumatopsyche speciosa , Hydropsyche hageni , Hydropsyche phalerata , Macrostemum zebratum ) and the mayfly Hexagenia (Ephemeridae) were used to examine inland distribution.
2. Inland dispersal was limited: catches of caddisflies declined at a greater than exponential rate with increasing distance from shore. Mean dispersal distance from the shoreline ranged from 650 to 1845 m. Smaller caddisfly species dispersed shorter distances than larger caddisflies and Hexagenia .
3. Inland distribution of adult caddisflies exhibited considerable interspecific variation: distribution was inconsistent among trials for Hexagenia , possibly owing to timing of collections in relation to periods of peak emergence.
4. Sex ratios of caddisflies were female biased at most sites. No consistent bias was observed for Hexagenia . Different inland distribution patterns were observed for males and females. The differences appeared to reflect species-specific reproductive strategies.     

捕食性天敌昆虫控害作用定量评价方法

天敌昆虫田间捕食作用与能力的研究,通常采用田间种群数量调查与分析的方法或笼罩试验来评价其控制作用,但往往与实际情况不符,尤其是对可捕食多种猎物的非专食性天敌,很难说明其在田间对某一特定猎物的控制作用究竟有多大,而分子生物学技术为捕食者-猎物关系评价研究提供了新途径。本文系统介绍了基于种特异性SS-PCR标记技术和TaqMan-MGB实时荧光定量PCR技术的捕食性天敌控害作用定量评价方法及其优缺点,旨在为害虫天敌的种类筛选及其保护利用提供技术指导。     

A new quantitative air-lift sampler for collecting macroinvertebrates on stony bottoms in deep rivers

SUMMARY. 1. As three previous comparative studies of deep-water samplers for benthic macroinvertebrates in rivers highlighted the need for a quantitative sampler for use on stony substrata, a new air-lift sampler was developed. It can be operated from a small boat by two people, weighs 13.5–20.0 kg, depending on the length of riser used, and extends the maximum range of substrata that may be sampled quantitatively from 16–32 mm to 128—256 mm. The sampling area is isolated by forcing a collecting cylinder into the substratum, and rapid evacuation of the contents is assisted by a vibrator.
2. All the major specifications of the sampler were determined experimentally in a large tank using three sizes of substrata and plastic pellets to represent invertebrates. The sampler performed accurately to a depth of at least 8 cm on substrata ranging from gravel (2–4 mm) to large stones (32–36 mm long).
3. The performance of the sampler was compared with that of a Ponar grab and Pearson el at. air-lift sampler at two sites on a large river and also with a Naturalist's dredge and a diver-operated Hess-Waters sampler at one of the sites where there were large stones up to 280 mm long. In terms of both mean taxa per sample and mean numbers m⁻², samples taken using the new air-lift sampler provided estimates comparable to or belter than those obtained with the other samplers.     

Ammonia transport by terrestrial and aquatic insects

Ammonia, an end product from amino acid and nucleic acid metabolism, is highly toxic for most animals. This review will provide an update on nitrogen metabolism in terrestrial and aquatic insects with emphasis on ammonia generation and transport. Aspects that will be discussed include metabolic pathways of nitrogenous compounds, the origin of ammonia and other nitrogenous waste products, ammonia toxicity, putative ammonia transporters as well as ammonia transport processes known in insects. Ammonia transport mechanisms in the mosquito Aedes aegypti, the tobacco hornworm Manduca sexta and the locust Schistocerca gregaria will be discussed in detail while providing additional, novel data.     

武夷山地区水生昆虫种类调查

通过灯诱、扫网和饲养(蜻蜒)等方法,系统调查了武夷山及其周边县市的水生昆虫,共获7目、48科、254种,比武夷山自然保护区10年科考结果又增加分布新记录13科,93种。     

A microbial sampler for freshwaters

A freshwater sampler using five sterile evacuated glass tubes is described. Water enters when a rubber stopper is mechanically removed from the end of a sterile hypodermic needle inserted into each tube. Plate counts of bacterial colonies were compared with those obtained with other samplers.     

A 'polarisation sun-dial' dictates the optimal time of day for dispersal by flying aquatic insects

1. Daily changes in the flight activity of aquatic insects have been investigated in only a few water beetles and bugs. The diel flight periodicity of aquatic insects and the environmental factors governing it are poorly understood. 2. We found that primary aquatic insects belonging to 99 taxa (78 Coleoptera, 21 Heteroptera) fly predominantly in mid‐morning, and/or around noon and/or at nightfall. There appears to be at least four different types of diurnal flight activity rhythm in aquatic insects, characterised by peak(s): (i) in mid‐morning; (ii) in the evening; (iii) both in mid‐morning and the evening; (iv) around noon and again in the evening. These activity maxima are quite general and cannot be explained exclusively by daily fluctuations of air temperature, humidity, wind speed and risks of predation, which are all somewhat stochastic. 3. We found experimental evidence that the proportion (%) P(θ) of reflecting surfaces detectable polarotactically as ‘water’ is always maximal at the lowest (dawn and dusk) and highest (noon) angles of solar elevation (θ) for dark reflectors while P(θ) is maximal at dawn and dusk (low solar elevations) for bright reflectors under clear or partly cloudy skies. 4. From the temporal coincidence between peaks in the diel flight activity of primary aquatic insects and the polarotactic detectability P(θ) of water surfaces we conclude that the optimal times of day for aquatic insects to disperse are the periods of low and high solar elevations θ. The θ‐dependent reflection–polarisation patterns, combined with an appropriate air temperature, clearly explain why polarotactic aquatic insects disperse to new habitats in mid‐morning, and/or around noon and/or at dusk. We call this phenomenon the ‘polarisation sun‐dial’ of dispersing aquatic insects.     

The role of lipids as feeding stimulants for shredding aquatic insects

SUMMARY.

• 1 Caddisflies (Trichoptera) that shred leaf detritus preferentially ingested lipid-coated detritus during the last larval in star. This is the interval when these insects accumulate the triglyceride reserves necessary for metamorphosis and reproduction. Early in star larvae, which do not accumulate lipids, showed no preference for any lipids. This behaviour indicates food selection based on changing nutritional needs.
• 2 Pure unsaturated 18- and 20-carbon fatty acids, either as free acids or triglycerides, were most strongly preferred. Crude lipid and the neutral lipid fraction from aquatic hyphomycete fungi, an important component of aquatic leaf detritus, were also preferred.
• 3 Tipula abdominalis (Diptera: Tipulidae) did not prefer any lipids during the last instar.

     

Characterization of benthic microhabitat: An experimental system for aquatic insects

An experimental system used to determine microhabitat current velocity and microhabitat selection by aquatic insects is described. The experimental system includes a microvelocity probe and a hydraulically calibrated artificial substrate. A thermistor velocity probe detects flow velocities to 0.5 m s^–1 near the surface of substrates at locations inhabited by aquatic insects. The artificial substrate was designed to provide two major habitat types, highly turbulent vortex areas and regions with unidirectional, near laminar flow. Substrate calibration and microhabitat characteristics of the substrates are demonstrated. Experimental studies of Simulium sp. location on substrates indicated that while simuliid larvae are characteristic of lotic, erosional habitats, actual microhabitats selected are governed by substantially lower flow velocity.     

Temporal variations of trace metals in aquatic insects

1. Temporal fluctuations were measured in the concentrations of the trace metals cadmium (Cd), copper (Cu) and zinc (Zn) in six insect taxa collected from the same sites in a temperate zone lake over a 14-month period. The consequences of temporal changes in insect contaminant concentrations for biomonitoring studies are assessed. 2. Significant temporal fluctuations in the concentrations of the three metals were measured in almost all of the insect taxa studied. In no case was there a greater than sixfold change in the concentration of a trace metal over the course of the year. The extent of the fluctuations was generally greater for CD, a non-essential metal, than for the essential micronutrients Cu or Zn. 3. Temporal fluctuations in CD concentrations appeared to follow a seasonal periodicity for most taxa. Minima were measured during the winter period in the megalopteran Sialis spp. and in the dipteran taxa Chaoborus punctipennis, Glyptotendipes sp., and Procladius spp., whereas a maximum was measured in the mayfly Hexagenia Hmbata during the same season. In general, temporal fluctuations in Cu and Zn concentrations were less seasonal in character than were those of Cd. 4. For some of the taxon—metal combinations studied, temporal fluctuations in metal concentrations could be ignored in biomonitoring studies, whereas in other cases a temporal window of minimum variability should be chosen for the collection of organisms from different sites.     

A technique for quantitative evaluation of ectoparasitic mites and insects of domestic animals

A modified KOH dissolution technique using Tween 80 has been developed for the diagnosis and quantitative evaluation of ectoparasitic mites and insects of veterinary importance. Fifty intact skin segments from ten different domestic animals were artificially inoculated in vitro with ten specimens each of the mitesSarcoptes scabiei, Chorioptes bovis, Psoroptes ovis andDemodex caprae and insectsHaematopinus eurysternus andBovicola bovis. Sixty-seven to 88% of the mites and 80–99% of the insects were recovered by this technique. Using this method, parasitic mites and insects were found and identified in all skin scrapings from ten naturally infested animals. Using Cook's dissolution technique in our experimental design, 63.4% ofC. bovis and 65% ofS. scabiei mites were recovered.