Exploration of the utility of fluctuating asymmetry as an indicator of river condition using larvae of the caddisfly Hydropsyche morosa (Trichoptera: Hydropsychidae)

Organisms are subject to three types of morphological asymmetry: Directional Asymmetry, Antiasymmetry and Fluctuating Asymmetry, but only the latter (FA) is related to the environmental stress acting upon individuals during their development. Larvae of Hydropsyche morosa from five rivers in Ontario, Canada, each exhibiting different degrees of human impact, were examined for FA. Specimens were obtained from collections in the Royal Ontario Museum dating back to 1951, and from fresh collections to 1999. Twelve morphological characters were assessed on both the left and right sides of 297 larvae, and eight of them demonstrated FA. There was a tendency to increase the levels of FA over time. Levels of nitrogen, conductivity and chloride in the river water, used as an index of pollution, were significantly and positively correlated with increasing incidence of FA in four of the characters, the remainder were independent of pollution.     

Insights into species diversity of the genus Hydropsyche Pictet, 1834 (Hydropsychidae,Trichoptera) from the Lake Kinneret catchment (Israel)

Species identification based on larval stages of aquatic insects in Israel is difficult, given the paucity of taxonomic studies. In order to gain deeper understanding of biological processes in Israel's freshwater ecosystems and to develop a bioindication system, species have to be known and characterised at all life stages. Here, we applied an integrative morphological and genetic approach to characterise caddisflies of the genus Hydropsyche Pictet, 1834 from the Lake Kinneret catchment. Seventeen sites in the Lake Kinneret catchment were sampled in spring/summer 2015 and 2016. For 77 hydropsychid larvae and two adult specimens of H. yahfufah Malicky, 2001, we analysed a 658 bp fragment of the mitochondrial COI gene and compared the results of different genetic species delimitation methods to observed morphological variation. Our results suggest the presence of at least five species. This study is an important first step towards assessing stream biodiversity of a yet largely understudied region and highlights advantages of integrative taxonomic approaches.     

The Larva of Hydropsyche tabacarui Botosaneanu, 1960 (Trichoptera: Hydropsychidae), Including a Re-description of the Female

The larva of Hydropsyche tabacarui Botosaneanu, 1960 is described and compared with the morphologically very similar larva of H. tibialis McLachlan, 1884. Information for the identification of both species is given and some zoogeographical and ecological notes are presented. In addition, the female of H. tabacarui is re-described.     

Patterns of pupal mortality in field populations of Hydropsyche and Cheumatopsyche (Trichoptera: Hydropsychidae)

SUMMARY. 1. Up to 40% of hydropsychid pupal cases (from three stations on the Credit and Humber Rivers, Ontario, Canada) contained insects already dead when collected; chironomid infestation accounted for up to 82% of total mortality within a taxon from any one station. The remaining mortality appeared to be due to siltation.
2. For all taxa ( Cheumatopsyche Wallengren and four species of Hydropsyche Pictet), and at all stations, prepupae suffered significantly more chironomid-related mortality than did fully-developed pupae.
3. Chironomid infestation generally affected all species of Hydropsyche equally; at some stations, Cheumatopsyche pupae appeared to suffer less chironomid-related mortality than did co-existing Hydropsyche species.
4. Chironomid infestation affected a greater proportion of pupae at the station where the density of pupal cases (per sampling quadrat) was greatest.
5. Vertical distribution of the pupation site had no apparent influence on mortality attributed to either siltation or chironomid infestation.
6. Chironomid infestation varied seasonally; it was greatest in May and July-August at an upstream station, and peaked in June at the downstream stations.
7. Mortality attributed to siltation was relatively constant for all stages and taxa, at all stations, throughout the sampling programme.     

The life cycle of an introduced caddisfly,Cheumatopsyche pettiti (Banks) (Trichoptera: Hydropsychidae) in Waikolu Stream,Molokai, Hawaii

Hawaiian streams contain some of the most unique species of aquaticinvertebrates known. In the 1960's a North American net spinningcaddisfly, Cheumatopsyche pettiti was inadvertentlyintroduced and is found in most perennial streams on Oahu, Maui,Molokai and Kauai. We investigated the life cycle of thistemperately evolved caddisfly in Waikolu Stream, Molokai. The lifecycle of C. pettiti was interpreted as probably multivoltinewith continuous recruitment throughout the year. At all samplingdates, instars I–V were present as well as pupae and adults.Detritus accounted for >50% of the gut contents of all larvae.Diatoms and other algae accounted for the remaining 50% of thediet. Cheumatopsyche pettiti has also apparently adapted toextremes in stream flows by building smaller capture nets andrudimentary retreats, usually on bedrock or firmly embeddedcobble.     

Isolation and characterization of microsatellite markers in the caddisfly Drusus discolor (Trichoptera: Limnephilidae)

We describe the development of and amplification conditions for microsatellite primers isolated from the caddisfly Drusus discolor. Eight polymorphic microsatellite loci were developed and screened for variability using 37 individuals from two populations from central Europe. The primers yielded an average of 8.6 alleles per loci. No linkage disequilibrium between loci was detected, while three loci showed deviations from Hardy–Weinberg equilibrium in one of the two tested populations.     

Substratum preference of the caddisfly Helicopsyche borealis (Hagen) (Trichoptera: Helicopsychidae)

The position of Helicopsyche borealis (Hagen) (Trichoptera: Helicopsychidae) larvae on the substratum surface is dependent on the current regime but varies with larval size. All size classes of larvae chose significantly different positions on the substratum under high versus low current velocities. All size classes preferred exposed surfaces under low current velocities. Small larvae preferred the upper surfaces of substrata under low current velocities and were physically displaced under high current velocities. Larger larvae also occurred on upper surfaces, but were more evenly dispersed over all surfaces than smaller larvae, and tended to aggregate on down-stream faces of rocks during high flow.     

Labial Gland and Its Protein Patterns of Hydropsychid Caddisfly (Hydropsyche kozhantschikovi Martynov: Trichoptera)

ABSTRACT There is a pair of labial gland of hydropsychid caddisfly ( Hydropsyche kozhantschikovi Martynov) larva. It is in 'Z' formation in the body and the total length is about 20 mm. Hydropsychid caddishfly larvae that were raised under the lab conditions were able to form a nest-spining by connecting the small grains of sand provided. By repeatedly treating the extracted labial gland with methanol/D.W., the cell layer was removed. Accordingly, only the matrix within the labial gland that did not dissolve in water was obtained. The matrix inside the methanol/D.W. treated labial gland was dissolved with 5% acetic acid. Then the results of an acidic electrophoresis with a number of conditions indicated that 5% acetic acid/ 5 M urea/ 8% PAGE was the most effective. Moreover, the result of 2-D PAGE on the labial gland of these hydropsychid caddisfly larva, the number of proteins in the labial gland including the cell layer was about 350 and the number of proteins in the labial gland treated with methanol/D.W. was about 80, showing a substantially small number of proteins.     

Insular radiation of the genus Hydropsyche (Insecta,Trichoptera: Hydropsychidae) Pictet, 1834 in the Philippines and its implications for the biogeography of Southeast Asia

Aims To record and elucidate the phylogeny and biogeography of a species swarm of the genus Hydropsyche (Insecta, Trichoptera) in the Philippines. All species belong to the hamifera group. Location The Philippines and neighbouring areas. Methods A phylogenetic analysis based on variation of morphological characters of the male phallic apparatus. Results The species swarm is differentiated into three clades of different age. Conclusion Alternative dispersal and vicariance hypotheses are considered in an attempt to explain the colonization of the Philippine archipelago and the subsequent ramification of the group. The vicariance hypothesis based on the late Miocene accretion of continental fragments to the Philippines appears to be the most parsimonious. The evolution of the swarm occurred on the Philippines. Later on species dispersed to Borneo, Sulawesi and the Moluccas. The species swarm has undergone an adaptive radiation which enabled the simultaneous occurrence of species in the same streams.     

Effects of Pacific salmon spawning and carcass availability on the caddisfly Ecclisomyia conspersa (Trichoptera: Limnephilidae)

1. The effects of spawning coho (Oncorhynchus kisutch) and chum salmon (Oncorhynchus keta) on the limnephilid caddisfly Ecclisomyia conspersa were evaluated by experimentally excluding salmon from the upper 14‐m stretch of a spawning channel by a wire‐meshed fence. Density, and development and growth rates, of larvae upstream of the fence (without salmon) were compared with those downstream (with salmon). 2. Larval density in the stretch with salmon declined during spawning, but increased again after spawning subsided and the carcasses of dead fish became available. In the stretch with salmon, larval density on salmon carcasses was seven to 37 times greater than on the adjacent channel substratum. The rate of larval development in the stretch with salmon was greater than that in the stretch without salmon. Two months after carcasses became available, 98% of larvae sampled from the stretch with salmon were in the fifth instar, compared to only 23% from the stretch without salmon. Body weight of E. conspersa in the stretches with and without salmon increased by an average of 3.04 and 2.38 mg, respectively, over a 6‐month period. 3. ¹⁵N values of larvae from the stretch with salmon increased following the arrival of the fish, suggesting that the larvae were feeding on salmon‐derived material, such as eggs and carcasses, which contain a high proportion of the heavier stable isotope. In contrast, ¹⁵N values of larvae from the stretch without salmon remained relatively constant throughout the experiment. The availability of salmon carcasses as a high‐quality food source late in larval development may increase survival and fecundity of E. conspersa. 4. These substantial differences were consistent with the view that they were due to the experimental exclusion of salmon and salmon carcasses from the upstream stretch, though the study was un‐replicated and thus precludes ascribing causation more definitely.     

侧枝纹石蛾亚属中国种类记述(毛翅目:纹石蛾科:纹石蛾属)

H.H.Ross和John D.Unzicker于1977年将纹石蛾属Branta组的种类建立一个新亚属——侧枝纹石蛾亚属Ceratopsyche,并移入Symphitopsyche属。A.Nielsen(1981)进一步将其提升为属。而P.W.Schefter等(1986)认为仍作为纹石蛾属的亚属较为适当。此亚属均分布于北半球,其中新北区30种,印度——马来区3种,古北区35种。中国目前已知9种,本文又发现9新种和3新记录种。中国种类的雄成虫检索表和新种、新记录种的描述如后。新种模式标本保存于南京农业大学植保系。     

Net-building behaviour,tolerance and development of two caddisfly species from the river Rhine (Hydropsyche contubernalis and H. pellucidula) in relation to the oxygen content

Summary Tolerance, growth and development of H. contubernalis and H. pellucidula were analyzed at different O₂-concentrations to determine the species specific potency amplitude in relation to O₂-concentration. In addition netbouilding behaviour was compared at different O₂-concentrations and current velocities. Under anaerobic conditions slightly greater tolerance was observed in H. contubernalis than in H. pellucidula. But at a higher O₂-concentration H. contubernalis showed a distinctly higher O₂-deficiency tolerance than H. pellucidula in relation to net-building activity, growth and development. In addition, more than 50% of H. contubernalis instars built capture nets with regular meshes at an O₂-saturation of only 30% (15°C). High growth rates were also found at 50% O₂-saturation and more than half the larvae developed into imagos. In addition to diminished net-spinning activity the mean growth rate started to decrease at an O₂-saturation of 70% to 38% and the development into an imago was not possible in H. pellucidula. Because H. contubernalis corresponds to a regulative type, being able to maintain a high level of netbuilding activity, growth rate and development over a wide range (50% to 100% O₂-saturation). On the other hand H. pellucidula corresponds to a conform type, because physiological efficiency decreases rapidly with falling O₂-concentration, so that development into an imago is no longer possible below 85% O₂-saturation. Positive correlation between net-spinning activity and tested current velocity between 10 cm/s and 25 cm/s (15°C) was found in H. pellucidula. H. contubernalis showed no change in net-building activity, over this range of current velocity. H. contubernalis can be classified as an euryoecious species with a great potency amplitude in relation to O₂-concentration and current velocity. The high tolerance to O₂-deficiency conditions probably allowed the early recolonization of the Mittel-and Niederrhein when a distinct O₂-deficit (mean 29%, max 56%) could still be measured. H. contubernalis can be considered a bioindicator of O₂-deficiency situations. Undisturbed development of H. pellucidula in this section of the river requires a further improvement in O₂-content.     

Effects of larval energetic resources on life history and adult allocation patterns in a caddisfly (Trichoptera: Phryganeidae)

Abstract 1. How populations respond to environmental change depends, in part, on the connection between environmental variance during early life stages and its effect on subsequent life‐history traits. For example, environmental variation during the larval stage can influence the life histories of organisms with complex life cycles by altering the amount of time spent in each stage of the life cycle as well as by altering allocation to life‐history traits during metamorphosis. 2. The effects of larval energetic resources on developmental timing, adult mass, fecundity, mating success, and allocation to adult body structures (thorax, abdomen, wings) were examined in an aquatic caddisfly (Agrypnia deflata Milne, Trichoptera: Phryganeidae). Larval energetic reserves were manipulated by removing larval cases just prior to pupation. In the first experiment, cases of all individuals were removed just prior to pupation; experimental individuals were required to build a new case whereas control individuals were allowed to re‐enter their case without building. In the second experiment, energy differences were maximised between the two treatments by supplementing the larval diet of the control group and removing cases and not supplementing the diet of the experimental group. 3. Male and female development time, adult mass, and female fecundity were not influenced by case removal or diet supplementation. In contrast, allocation to adult body parts indicated a trade‐off between abdominal and thoracic mass among case‐removal females, suggesting that, under larval resource stress, females adjust resource allocation during metamorphosis to alleviate potential negative impacts on clutch size. In addition, latency to copulation increased when cases were removed, indicating larval resource stress could influence male mating success. 4. This study suggests that, under larval energetic stress, the negative impacts on female reproduction might be mitigated by re‐allocating resources during metamorphosis, whereas male allocation strategies might not be as flexible as female strategies.     

Location of copper in larvae of Plectrocnemia conspersa (Curtis) (Trichoptera) exposed to elevated metal concentrations in a mine drainage stream

Using histological techniques together with transmission electron microscopy and X-ray microanalysis, copper-containing granules (which also contain significant amounts of sulphur) have been observed in the cells of the malpighian tubules and in the subcuticular region of larvae of Plectrocnemia conspersa. It is suggested that the granules in both these regions are primarily pigment granules, which provide a mechanism for taking potentially toxic concentrations of copper (and possibly other metals) out of circulation. This mechanism of metal tolerance may in part account for the reported occurrence of larvae of P. conspersa in waters with elevated concentrations of trace metals.     

Dietary variations of predaceous caddisfly larvae (Trichoptera: Rhyacophilidae,Polycentropodidae and Arctopsychidae) from British Columbian streams

The diets of larval Rhyacophilidae (Rhyacophila inculta), Polycentropodidae (Polycentropus variegatus) and Arctopsychidae (Parapsyche almota and P. elsis) from five streams in the University of British Columbia Research Forest, British Columbia (Canada), are recorded and related to feeding mode/constructional activities and prey representation in the habitat. Particular attention was paid to the extent of dietary overlap and the degree of intraspecific dietary variations between streams. An overall similarity of the diets of the study species was notable and all commonly consumed chironomid (Diptera) larvae, Simulium (Diptera) and Zapada (Plecoptera), although there was interspecific variation in the relative importance of these items. Polycentropus variegatus and Parapsyche spp. ate Baetis and Paraleptophlebia, the latter predators also consuming Hydrachnellae (Acarina). Other prey were generally of minor importance and consequently interspecific dietary overlaps were high. Differences in the range of prey consumed by predaceous Trichoptera were apparent. Free-foraging R. inculta which selectively consumed sedentary simuliid larvae had the narrowest niche breadth. Parapsyche spp. and Polycentropus variegatus foreguts generally contained an over-representation of chironomid larvae compared to their proportionate occurrence in the benthos, and these caddisflies exhibited high niche overlap. The relative importance of chironomids as food for Parapsyche spp. and Polycentropus variegatus is attributed to prey behaviour, i.e. drift, and poorly developed escape responses when they are caught on the predator's net.     

A new species of Amphoropsyche (Trichoptera, Leptoceridae) from Ecuador, with a key to the species in the genus

A new species of Amphoropsyche Holzenthal is described from Ecuador. It is similar to a group of species with dorsomesal processes on the preanal appendages (i.e., Amphoropsyche woodruffi Flint & Sykora, Amphoropsyche refugia Holzenthal, and Amphoropsyche aragua Holzenthal), but can be distinguished from these and other members of the genus by the short, digitate dorsomesal processes on the preanal appendages and the broad lateral processes of tergum X of the male genitalia. A key to males of the 14 species now known in the genus is presented based on characters of the genitalia.     

Unusual behaviour and morphology of some Rhyacophila Pictet, 1834 caddisfly (Trichoptera: Rhyacophilidae) larvae reflect their ability to use the hyporheic zone

We found that larvae of four Rhyacophila Pictet, 1834 species preferred the hyporheic biotope in rapids and glides, which appears to be an unusual habitat among species in this genus. These species, i.e., Rhyacophila nigrocephala Iwata, 1927, R. nipponica Navas, 1933, R. shikotsuensis Iwata, 1927 and R. kawamurae Tsuda, 1940, belonging to the nigrocephala species group, of which six species occur in Japan. To study the movement behaviour of these species in the hyporheic biotope, we introduced their larvae into a small aquarium with a sandy bottom substrate. The larvae of these species burrowed into the sand bed and moved smoothly through interstices using their forelegs and their highly flexible and elastic abdomens. The larval morphology of these six species differs from that of the representatives of the other species group of Japanese Rhyacophila. They have more slender and flatter head capsules, more elongate abdominal segments, shorter thoracic legs and more slender anal prolegs. These features are adaptations that allow these species to effectively use the hyporheic biotope by enabling them to burrow through the interstices.     

The multivoltine life history of Cheumatopsyche brevilineata (Iwata, 1927) (Trichoptera: Hydropsychidae), with a new method to estimate the population size of generations

Cheumatopsyche brevilineata (Iwata, 1927 Iwata, M. (1927), ‘Trichopterous Larvae from Japan’, Zoological Magazine, 39, 209–272. (In Japanese) [Google Scholar]) is a filter-feeding caddisfly without distinct separable generations. We conducted a life history survey of C. brevilineata under a natural thermal regime. This caddis species had a multivoltine life history and their generations partially overlapped each other. From the seasonal change of larval and pupal density, we recognized one overwintering generation and three non-winter generations. We propose a new method to estimate the population size of fourth instar larvae from each generation by using the ‘development zero’ and ‘effective degree-days’ methods. The second non-winter generation, developing under the hottest water temperature regime, had the largest population size and highest observed density. The overwintering generation, which developed under the coolest thermal regime, showed the smallest population size but its observed density was not the smallest.     

Phylogenetic,Spatial, and Species‐Trait Patterns across Environmental Gradients: the Case of Hydropsyche (Trichoptera) along the Loire River

When Illies published his concept on the longitudinal zonation of lotic invertebrates five decades ago (Illies, J., 1961: Internat. Rev. ges. Hydrobiol. 46 : 205–213), he defined a research topic that currently interests many ecologists because he linked speciation and phylogeny with spatial distribution and trait adaptation to environmental conditions prevailing along rivers. We tested these ideas analyzing nine species of the caddisfly genus Hydropsyche from the Loire River (France). A morphology‐based phylogeny illustrated that the oldest of our species occurred in the headwater and that specific phylogenetic distances from the root location in the tree were significantly related to the specific longitudinal occurrences in the Loire. Furthermore, traits such as oxygen consumption, optimal velocity for filter‐net‐building, and larval size were significantly related to the specific phylogenetic distances, indicating meaningful, gradual adaptations to environmental gradients prevailing along European rivers (particularly in water temperature, near‐bottom flow, sediment porosity). Thus, joining phylogeny, spatial distribution, and species traits provided insights into a central topic of contemporary ecology, the spatial patterns of speciation, taxonomic community structure (species distributions), and niche adaptation (traits). (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A new caddisfly of the fossil genus <Emphasis Type="Italic">Archaeotinodes</Emphasis> (Insecta: Trichoptera: Ecnomidae) from the Baltic amber

A new caddisfly species of the fossil genus Archaeotinodes, A. igneusaper sp. nov., is described from the Upper Eocene Baltic amber. The new species is close to A. pauper Ulmer, 1912 and A. lanceolata Ulmer, 1912 from the Baltic amber, differing from these in the structure of the male genitalia.