SEARCH · PubMed Health

Results for “Trichoptera”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources

PubMed2002

The validity of the Gammarus:Asellus ratio as an index of organic pollution: abiotic and biotic influences.

In freshwaters. Gammarus spp. are more sensitive to organic pollution than Asellus spp. and the relative abundance of the two taxa has been proposed as a pollution index. We tested the validity of this by examining the relationship between the Gammarus: Asellus (G : A) ratio and (1) a suite of physico-chemical variables. (2) established biotic (average score per taxon, ASPT) and richness (species richness (S) and Ephemeroptera, Plecoptera and Trichoptera families richness (EPT family richness)) indices generated from the macroinvertebrate community. In addition, we investigated a suspected biotic interaction, predation, between Gammarus and Asellus. Both univariate and multivariate analyses showed that the G: A ratio was sometimes responsive to changes in parameters linked to organic pollution, such as BOD5 and nitrate levels. However, the G : A ratio also appeared responsive to variables not directly linked to organic pollution, such as conductivity and distance from source. There were significant positive correlations among the G : A ratio and the ASPT, S and EPT, indicating that changes in the relative abundances of Gammarus and Asellus were reflected in changes in the pollution sensitivity and richness of the wider macroinvertebrate community. A laboratory experiment revealed significant predation of Asellus aquaticus juveniles by Gammarus duebeni celticus adults, but no reciprocal predation. We propose that the G: A ratio may be useful as a crude measure of organic pollution that could supplement more complex indices in a multimetric approach to pollution monitoring or be used for monitoring individual sites, where a simple technique is required for monitoring purposes over a period of time. Also, we urge recognition of the possible role of biotic interactions among taxa used in the generation of pollution indices.

Animals↗

PubMed2004

Relationship between macroinvertebrate fauna and environmental variables in small streams of the Dominican Republic.

Field assessment methods for freshwater macroinvertebrates and water quality in tropical small-island states were assessed in the Dominican Republic. Macroinvertebrate samples were collected from 26 river sites within the Dominican Republic's Yaque del Norte river catchment. Environmental data on geographical, physical and chemical variables were also collected from each site. The Biological Monitoring Working Party score and total numbers of Ephemeroptera and Trichoptera were calculated for each site. Physico-chemical and biological data sets were ordinated by principal components analysis and non-parametric multi-dimensional scaling, and the biotic and abiotic data sets were correlated to determine the most influential factors determining site similarities. Macroinvertebrate assemblage structure was correlated with declining water quality: however, a high correlation between water quality and altitude confounded an unqualified interpretation of impairment.

Animals↗

PubMed1996

The effects of a basic effluent on macroinvertebrate community structure in a temporary Mediterranean river.

Macroinvertebrate communities and environmental variables were assessed seasonally for 1 year in a temporary river in South Portugal receiving an effluent with high conductivity, pH, sulphates, nitrates and low oxygen content. The usefulness of the ordination method canonical correspondence analysis (CCA) and the classification method cluster analysis (UPGMA) were examined to evaluate the perturbation. Macroinvertebrate samples were segregated along the first ordination axis by CCA, which in turn correlated with sulphates and nitrates. CCA produced a two-dimensional distribution of sites similar to the grouping formed by cluster analysis. In general, three or four groups were distinguished. Immediately downstream of the effluent discharge point, only taxa tolerant to low oxygen, high pH and high sulphate and nitrate concentrations were present. Further downstream, sites had a community similar to the reference sampling locations. During flowing conditions the CCA ordination axis 1 was also correlated with several classic measures of water quality (i.e. taxon richness, diversity and biotic indices). In other periods, only the percentage of Ephemeroptera, Plecoptera and Trichoptera (%EPT) and the ratio EPT/(Chironomidae + EPT) were significantly correlated with CCA axis one. This suggests that ordination methods outperform benthic indices in detecting pollution during low flows and segregated polluted from clean/recovered sites in all periods.

Journal Article↗

PubMed1997

The effects of conservation tillage practices on benthic invertebrate communities in headwater streams in southwestern Ontario, Canada.

Samples of benthic invertebrates from four pairs of streams in southwestern Ontario collected monthly from May through August 1991, and once during the subsequent autumn and winter, demonstrated that conservation tillage practices have a remedial effect on the water quality of adjacent streams as indicated by biotic, rather than physical or chemical, parameters. One stream of each pair drained a basin under conventional tillage (CONV, mainly mouldboard ploughing), the other primarily under conservation tillage (CONS). The paired drainage basins were otherwise similar to one another in type of crops grown, as well as size, topography, soils and hydrology. CONS streams yielded a greater variety of Insecta but fewer taxa of Mollusca, Annelida and Crustacea than did samples from CONV streams. Both kick-net and Surber samples from CONS streams yielded significantly more taxa, more kinds of Ephemeroptera, Plecoptera and Trichoptera, and lower Hilsenhoff Biotic Index scores than did samples from CONV streams. Kick samples from CONS streams were significantly more similar to expected reference communities in overall taxonomic composition. Surber samples from CONS streams contained significantly larger numbers of invertebrates. The relatively greater abundances of infaunal species, especially Tubificidae and Chironomini, in CONV streams suggest greater accumulation of fine sediment particles. Conditions during low flow appear to have the greatest influence on the composition of benthic invertebrate communities. The results of the study indicate that conservation tillage practices have a beneficial effect on the quality of surface waters.

Journal Article↗

PubMed2000

Population structure of Hydropsyche exocellata. Genetic homogeneity in a zone of fragmented distribution.

Using four allozymic loci, we analysed the genetic structure and differentiation of Hydropsyche exocellata (Trichoptera; Hydropsychidae) larvae in seven sites along the Upper Loire River (France). The genetic differentiation is low for this species despite distribution patchiness, and only due to one locus in one study site. No trend relating genetic differentiation to geographic distance (isolation by distance) was observed. Significant deviations from Hardy-Weinberg equilibrium were observed at most sites and loci. The population genetics analysis of an amphibiotic insect such as H. exocellata in light of current ecological and population genetics knowledge is discussed following two main factors: 1) sampling of partially reproductively isolated, genetically distinct subpopulations, and 2) form of selection. Despite knowledge on several aspects of the ecology of H. exocellata in the River Loire, numerous points limit genetic data interpretation. These points are underlined and discussed with reference to studies on other amphibiotic insects.

Animals↗

PubMed2006

Protein composition of silk filaments spun under water by caddisfly larvae.

Silk fiber produced by the larvae of Trichoptera (caddisflies) and Lepidoptera (moths and butterflies) is composed of two filaments embedded in a layer of glue proteins. In an aerial environment Lepidoptera spin silk filaments assembled from heavy chain fibroin (H-fibroin), light chain fibroin (L-fibroin), and the glycoprotein P25. The silk filament of caddisflies, which is produced and persists in water, contained homologues of H-fibroin (>500 kDa) and L-fibroin (25 kDa) but not of P25. The amphiphilic nature of H-fibroin and its high content of charged amino acids probably facilitate the secretion and storage of a covalently linked L-fibroin/H-fibroin dimer in the absence of P25. Several types of short amino acid motifs were arranged in orderly fashion in the regularly reiterated repeats that made up more than 95% of the length of H-fibroin. The H-fibroins of Hydropsyche angustipennis and Limnephilus decipiens from different caddisfly suborders contained GPXGX, SXSXSXSX, and GGX motifs such as the lepidopteran and spider silks but differed from them by a lack of poly(A) and poly(GA) motifs. H-fibroins of both caddisfly species harbored a conserved repeat of 31 residues but were distinguished by a few species-specific motifs and their organization in higher order repeats. Structural differences may be related to the silk function as a catching net in H. angustipennis and a stitching fiber in L. decipiens.

Amino Acid Sequence↗

PubMed2004

Influence of total organic carbon and UV-B radiation on zinc toxicity and bioaccumulation in aquatic communities.

The effects of total organic carbon (TOC) and UV-B radiation on Zn toxicity and bioaccumulation in a Rocky Mountain stream community were assessed in a 10-d microcosm experiment. We predicted that TOC would mitigate Zn toxicity and that the combined effects of Zn and UV-B would be greater than Zn alone. However, TOC did not mitigate Zn toxicity in this study. In fact, treatments with TOC plus Zn had significantly lower community respiration as compared with the controls and Zn concentrations associated with the periphyton increased in the presence of TOC. UV-B had no additive effect on periphyton Zn accumulation or community respiration. Heptageniid mayflies (Ephemeroptera) were particularly sensitive to Zn, and reduced abundances were observed in all Zn treatments. UV-B did not additionally impact Heptageniid abundances; however UV-B did have a greater effect on macroinvertebrate drift than Zn alone. Ephemeroptera, Plecoptera, and Trichoptera (groups typically classified as sensitive to disturbance) were found in highest numbers in the drift of UV-B + Zn treatments. Measures of Zn accumulation in the caddisfly Arctopsyche grandis, periphyton biomass, and total macroinvertebrate abundance were not sufficiently sensitive to differentiate effects of TOC, UV-B, and Zn. These results indicate that UV-B and TOC affect Zn bioavailability and toxicity by impacting species abundance, behavior, and ecosystem processes.

Animals↗

PubMed2001

Testing bioassessment metrics: macroinvertebrate, sculpin, and salmonid responses to stream habitat, sediment, and metals.

The purpose of this article is to report on the testing of responses of multimetric macroinvertebrate and habitat indices to common disturbances to streams: stream habitat alteration, excessive sediment, and elevated metals concentrations. Seven macroinvertebrate community metrics were combined into a macroinvertebrate biotic index (MBI), and 11 channel morphology, riparian, and substrate features were combined into a habitat index. Indices were evaluated by comparing the habitat results to fish population surveys and comparing the macroinvertebrate results to habitat ratings, percent fine sediments measured by Wolman pebble counts, and copper concentrations. Macroinvertebrate scores decreased with increasing percentages of fine sediments measured either across the bankfull or instream channel widths. Macroinvertebrate scores decreased with increasing copper. One metric, richness of Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa, was more responsive to both copper and sediment than was the multimetric MBI. Habitat scores corresponded well with the age class structure of salmonids, but not with that of benthic sculpins. Both salmonid and sculpin age classes declined with increasing percentages of fine sediments. The decline was graded with the sculpin age classes, whether fine sediments were measured across the instream or bankfull channel, whereas salmonids consistently responded only to the instream fine sediments.

Animals↗

PubMed2002

Species diversity enhances ecosystem functioning through interspecific facilitation.

Facilitation between species is thought to be a key mechanism by which biodiversity affects the rates of resource use that govern the efficiency and productivity of ecosystems; however, there is no direct empirical evidence to support this hypothesis. Here we show that increasing the species diversity of a functional group of aquatic organisms induces facilitative interactions, leading to non-additive changes in resource consumption. We increased the richness and evenness of suspension-feeding caddisfly larvae (Insecta, Trichoptera) in stream mesocosms and found that the increased topographical complexity of the benthic habitat alters patterns of near-bed flow such that the feeding success of individuals is enhanced. Species diversity reduces 'current shading' (that is, the deceleration of flow from upstream to downstream neighbours), allowing diverse assemblages to capture a greater fraction of suspended resources than is caught by any species monoculture. The fundamental nature of this form of hydrodynamic facilitation suggests that it is broadly applicable to freshwater and marine habitats; in addition, it has several analogues in terrestrial ecosystems where fluxes of energy and matter can be influenced by biophysical complexity. Thus, changes in species diversity may alter the probability of positive species interactions, resulting in disproportionately large changes in the functioning of ecosystems.

Animals↗

PubMed2003

Dipteran predators of Simuliid blackflies: a worldwide review.

Haematophagous female blackflies (Diptera: Simuliidae) are serious biting pests and obligate vectors of vertebrate pathogens, namely filarial Dirofilaria, Mansonella, Onchocerca and protozoal Leucocytozoon. Immature stages of Simuliidae inhabit lotic waterways, the sessile larvae filter-feeding and often forming a large proportion of the benthic biomass, usually aggregated in well-oxygenated sections of streams, rivers, waterfalls and spillways. Simuliid control practices depend on larvicidal chemicals, biological products (bacteria, nematodes) and environmental modification. The potential use of predators for biological control of Simuliidae has not been exploited. Predators of Simuliidae include examples of at least 12 families of Diptera and other predaceous arthropods (Crustacea and insects: Coleoptera, Odonata, Plecoptera, Trichoptera), invertebrates (notably Turbellaria), as well as browsing fish. Diptera impacting upon simuliid populations comprise mainly Chironomidae, Empididae and Muscidae, although several other families (Asilidae, Dolichopodidae, Phoridae, Drosophilidae, Scathophagidae) play a significant role as predators. Details of predator and prey species and life stages are presented, by zoogeographical region, including the prevalence of cannibalism among Simuliidae.

Animals↗

PubMed2003

Determination of 'irritant' threshold concentrations for intradermal testing with allergenic insect extracts in normal horses.

Sixteen healthy horses with no history of skin or respiratory disease were used for an intradermal testing (IDT) threshold study, in order to determine the concentrations of 13 commercial allergenic insect extracts most appropriate for IDT. Five dilutions of each extract were used, which included the manufacturer's recommended concentrations for equine IDT, plus one dilution higher and three lower than these standard concentrations. Allergens tested included caddisfly (Trichoptera spp.), mayfly (Ephemeroptera spp.), horsefly (Tabanus spp.), deerfly (Chrysops spp.), fire ant (Solenopsis invicta), black ant (Camponotus pennsylvanicus), cockroach mix (Periplaneta americana and Blattella germanica), mosquito (Aedes aegypti), house fly (Musca domestica), moth (Heterocera spp.), flea (Ctenocephalides canis/C. felis), Culicoides variipennis and Culicoides nubeculosis. Two separate methods were used to calculate the allergen concentration for each insect extract where the normal horses, as a group, ceased to show false-positive ('irritant') reactions. 'Irritant' threshold concentrations were determined for 9/13 of these allergens, whereas the other 4 were undetermined due to either insufficient reactivity (flea, C. variipennis) or excessive reactivity (black ant, moth) to the concentrations tested. Recommended concentrations for future use in equine patients with suspected insect hypersensitivity include: 125 pnu mL(-1) (mayfly); 250 pnu mL(-1) (caddisfly, horsefly, deerfly, fire ant, house fly); 500 pnu mL(-1) (cockroach); 1000 pnu mL(-1) (mosquito); and 1:10 000 w/v (C. nubeculosis).

Allergens↗

PubMed2000

Developmental trade-offs and life histories: strategic allocation of resources in caddis flies.

Resource allocation trade-offs during development are potentially very important in the evolution of organism morphology and life-history strategy However, they have rarely been demonstrated empirically. To what extent the division of limited resources between growing organs is a consequence of particular developmental pathways or varies strategically in line with life-history predictions is unknown. It has been demonstrated in a number of holometabolous insects that altering the resources available at pupation changes the pattern of allocation to adult tissues, but this has not been examined in a life-history context. Using caddis flies (Trichoptera), we show here that the effect of depleted larval resources on the pattern of somatic and reproductive investment is not fixed but varies between species with different life-history patterns. In particular, we demonstrate that, in a long-lived species, thorax size is preserved, which contrasts with the pattern previously observed in a short-lived species. That the adult body can be differentially altered by the same resource depletion in the larvae demonstrates that the allocation of resources amongst body parts is not a consequence of fixed pathways during development. Rather, the allocation of resources during development can occur in a manner consistent with the minimization of the effects on adult fitness.

Animals↗

PubMed2002

Simulating species loss following perturbation: assessing the effects on process rates.

We removed stream-living macroinvertebrate shredder species in the sequences in which they are predicted to disappear, in response to two common types of anthropogenic disturbances: acidification and organic pollution, and analysed the effects on leaf breakdown rates. The experiment was performed in field microcosms using three shredder species. Species identity significantly affected leaf breakdown rates, while species richness per se was non-significant. The simulated sequential species loss showed large effects on leaf breakdown rates, with observed rates being significantly higher than expected from single-species treatments in two, out of four, two-species, and in all four three-species treatments. The invertebrates used in this study were taxonomically distinct (Insecta: Plecoptera and Trichoptera; Crustacea: Amphipoda), and of different sizes, hence a high degree of complementarity was probably present. A method to study the effects of species loss, characteristic of perturbation type, could be more useful than a random approach when investigating the impact of perturbation. Our results may have general applicability for investigations on the effects of diversity loss on ecosystem functioning in any ecosystem exposed to human perturbations, given that the order of extinction is known or can easily be assessed.

Amphipoda↗

PubMed2003

Impacts of marine-derived nutrients on stream ecosystem functioning.

Energy and nutrient subsidies transported across ecosystem boundaries are increasingly appreciated as key drivers of consumer-resource dynamics. As purveyors of pulsed marine-derived nutrients (MDN), spawning salmon are one such cross-ecosystem subsidy to freshwaters connected to the north Pacific. We examined how salmon carcasses influenced detrital processing in an oligotrophic stream. Experimental manipulations of MDN inputs revealed that salmon carcasses indirectly reduced detrital processing in streams through temporarily decoupling the detrital resource-consumer relationship, in which detrital consumers shifted their diet to the high-nutrient resource, i.e. salmon carcasses. The average decomposition rate of alder leaves with salmon carcass addition was significantly lower than that without the carcass, which was associated with lower abundance and biomass of detritivorous Trichoptera on the carcass-treated leaves. There were generally larger in size Trichopteran detritivores on the carcasses than on leaves. These results imply that cross-boundary MDN subsidies indirectly retard the ecosystem processing of leaf litter within the short term, but may enhance those food-limited detritivorous consumers. Because unproductive freshwaters in the Pacific northwest are highly dependent upon the organic matter inputs from surrounding forests, this novel finding has implications for determining conservation and management strategies of salmon-related aquatic ecosystems, in terms of salmon habitat protection and fisheries exploitation.

Analysis of Variance↗

PubMed2006

The rapid divergence of the ecdysone receptor is a synapomorphy for Mecopterida that clarifies the Strepsiptera problem.

In arthropods, the regulation by ecdysteroids is mediated by the heterodimer between the ecdysone receptor (ECR; NR1H1) and ultraspiracle (USP/RXR; NR2B4) nuclear receptors. Both ECR and USP/RXR ligand-binding domains experienced a strong acceleration of evolutionary rate in Diptera and Lepidoptera, which belong to the superorder Mecopterida. We performed a phylogenetic analysis of 28 ECR and 30 USP/RXR protein sequences from 36 arthropod species, including representatives from Trichoptera, Mecoptera and Siphonaptera. Our data show that the acceleration of ECR and USP/RXR was a unique event in the ancestor of Mecopterida. Our analysis shows further that Strepsiptera ECR and USP/RXR sequences are unambiguously placed outside of the Mecopterida clade. Protein alignments reveal that eight of 11 synapomorphies support an affinity between Strepsiptera and Coleoptera sequences. The affiliation of Strepsiptera to Diptera should therefore be rejected.

Animals↗

PubMed1983

Comparison of degradative ability, enzymatic activity, and palatability of aquatic hyphomycetes grown on leaf litter.

Stream fungi have the capacity to degrade leaf litter and, through their activities, to transform it into a more palatable food source for invertebrate detritivores. The objectives of the present study were to characterize various aspects of fungal modification of the leaf substrate and to examine the effects these changes have on leaf palatability to detritivores. Fungal species were grown on aspen leaves for two incubation times. Leaves were analyzed to determine the weight loss, the degree of softening of the leaf matrix, and the concentrations of ATP and nitrogen associated with leaves. The activities of a protease and 10 polysaccharide-degrading enzymes produced by each fungus were also determined. Most fungi caused similar changes in physicochemical characteristics of the leaves. All fungi exhibited the capability to depolymerize pectin, xylan, and cellulose. Differences among fungi were found in their capabilities to produce protease and certain glycosidases. Leaf palatability was assessed by offering leaves of all treatments to larvae of two caddisfly shredders (Trichoptera). Feeding preferences exhibited by the shredders were similar and indicated that they perceived distinct differences among fungi. Two fungal species were highly consumed, some moderately and others only slightly. No relationships were found between any of the fungal characteristics measured and detritivore feeding preferences. Apparently, interspecific differences among fungi other than parameters associated with biomass or degradation of structural polysaccharides influence fungal palatability to caddisfly detritivores.

Journal Article↗

PubMed2004

Phylogenetic distribution of TTAGG telomeric repeats in insects.

We examined the presence of TTAGG telomeric repeats in 22 species from 20 insect orders with no or inconclusive information on the telomere composition by single-primer polymerase chain reaction with (TTAGG)6 primers, Southern hybridization of genomic DNAs, and fluorescence in situ hybridization of chromosomes with (TTAGG)n probes. The (TTAGG)n sequence was present in 15 species and absent in 7 species. In a compilation of new and published data, we combined the distribution of (TTAGG)n telomere motif with the insect phylogenetic tree. The pattern of phylogenetic distribution of the TTAGG repeats clearly supported a hypothesis that the sequence was an ancestral motif of insect telomeres but was lost repeatedly during insect evolution. The motif was conserved in the "primitive" apterous insect orders, the Archaeognatha and Zygentoma, in the "lower" Neoptera (Plecoptera, Phasmida, Orthoptera, Blattaria, Mantodea, and Isoptera) with the exception of Dermaptera, and in Paraneoptera (Psocoptera, Thysanoptera, Auchenorrhyncha, and Sternorrhyncha) with the exception of Heteroptera. Surprisingly, the (TTAGG)n motif was not found in the "primitive" pterygotes, the Palaeoptera (Ephemeroptera and Odonata). The Endopterygota were heterogeneous for the occurrence of TTAGG repeats. The motif was conserved in Hymenoptera, Lepidoptera, and Trichoptera but was lost in one clade formed by Diptera, Siphonaptera, and Mecoptera. It was also lost in Raphidioptera, whereas it was present in Megaloptera. In contrast with previous authors, we did not find the motif in Neuroptera. Finally, both TTAGG-positive and TTAGG-negative species were reported in Coleoptera. The repeated losses of TTAGG in different branches of the insect phylogenetic tree and, in particular, in the most successful lineage of insect evolution, the Endopterygota, suggest a backup mechanism in the genome of insects that enabled them frequent evolutionary changes in telomere composition.

Animals↗

PubMed2005

Insect gas exchange patterns: a phylogenetic perspective.

Most investigations of insect gas exchange patterns and the hypotheses proposed to account for their evolution have been based either on small-scale, manipulative experiments, or comparisons of a few closely related species. Despite their potential utility, no explicit, phylogeny-based, broad-scale comparative studies of the evolution of gas exchange in insects have been undertaken. This may be due partly to the preponderance of information for the endopterygotes, and its scarcity for the apterygotes and exopterygotes. Here we undertake such a broad-scale study. Information on gas exchange patterns for the large majority of insects examined to date (eight orders, 99 species) is compiled, and new information on 19 exemplar species from a further ten orders, not previously represented in the literature (Archaeognatha, Zygentoma, Ephemeroptera, Odonata, Mantodea, Mantophasmatodea, Phasmatodea, Dermaptera, Neuroptera, Trichoptera), is provided. These data are then used in a formal, phylogeny-based parsimony analysis of the evolution of gas exchange patterns at the order level. Cyclic gas exchange is likely to be the ancestral gas exchange pattern at rest (recognizing that active individuals typically show continuous gas exchange), and discontinuous gas exchange probably originated independently a minimum of five times in the Insecta.

Animals↗