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At least 37 records · Page 2Linked to original sources
PubMed1976

Studies on silk secretion in the Trichoptera (F. Limmephilidae). II. Structure and amino acid composition of the silk.

The ultrastructure and amino acid composition of the secreted silk of two species of trichopteran larvae, Pycnopsyche guttifer (Walk.) and Neophylax concinnus McL., were investigated. The spinnerets of these two animals were also examined by scanning electron microscopy. The silk consists of double-stranded, flat ribbons (1-4 mu wide), composed of bundles of 15-25 A filaments. There are two components of the silk: the fiber proper and a surrounding coat thought to be a silk "gum". Only the outer coat is positive to the EM PATP technique of Thiery (1967), which indicated the presence of neutral sugars. Amino acid analyses of Pycnopsyche silk show that, like other silks, two predominant amino acids are glycine and serine. Arginine, unexpectedly, is the third most abundant and there are a large number of basic and long side-chain amino acids. X-ray diffraction studies of the silk indicate that it has a less crystalline, more amorphous structure than that of other silks.

Amino Acids↗
PubMed1999

Caddisflies (Trichoptera: Hydropsychidae) used for evaluating water quality of large European rivers.

In many European rivers, biodiversity has declined dramatically, and especially riverine insects have disappeared during the past decades. It remains unclear whether poor water quality or deteriorated habitats are limiting the distribution of sensitive aquatic insects in these rivers. The aim of this study, therefore, was to find out if water quality alone is limiting the distribution of these insects in rivers that have suffered from anthropogenic disturbances. To this purpose, caddisflies of the genus Hydropsyche, which are representative riverine insect species, were incubated in two large European rivers, the Rhine and the Meuse. Survival of caddisflies in the River Rhine was fairly high, while there was almost no survival in the River Meuse in three out of five field experiments. The incubations of Hydropsyche in the River Meuse provide evidence that even adequate structural habitat would be insufficient for the reestablishment of Hydropsyche species. The factors limiting the distribution of Hydropsyche species change with the changing constitution of the water; there is not one (group of) compound(s) responsible for the poor water quality. Besides chemical factors, physical factors (like oxygen and current velocity) may be limiting in the River Meuse for Hydropsyche species.

Animals↗
PubMed1990

Relationships between copper concentrations in larvae of Plectrocnemia conspersa (Curtis) (Trichoptera) and in mine drainage streams.

Elevated copper concentrations were determined for single larvae of Plectrocnemia conspersa in a copper-rich stream. Although larval copper concentration was reduced by at least 50% after clearing gut contents, its exponential decrease with increasing body weight remained unchanged. Analysis of instar V larvae from different sampling stations showed a steep increase in the concentration of copper in the larvae with that in the water at lower stream water concentrations, followed by a progressively less steep increase at higher stream concentrations. When captive larvae from a clean stream were introduced into a mine drainage stream, the amount of copper in fed and unfed larvae steadily increased, suggesting metal uptake from water and food. Survival and growth were comparable for introduced and captive resident larvae suggesting copper tolerance to be a general characteristic of P. conspersa.

Journal Article↗
PubMed1992

Recovery of acid-sensitive species of ephemeroptera, plecoptera and trichoptera in river audna after liming.

River Audna has been continuously limed on a full scale basis since 1985. Monitoring of benthic invertebrates of the river showed that the fauna was dominated by acid-tolerant species before liming and during the first year after the start of the treatment. Moderately acid-sensitive species, like Diura nanseni, Isoperla grammatica and Hydropsyche siltalia were found only in small numbers in a few localities in this period. In autumn 1987, the first appearance of the highly acid-sensitive mayfly Baetis rhodani was recorded at two stations in the main river. During the following years, this species colonized other localities and several other sensitive invertebrates, such as Heptagenia sulphurea, Caenis horaria, Hydropsyche pellucidula and Lepidostoma hirtum were also recorded. The change in faunal composition was highly significant compared to unlimed reference stations.

Journal Article↗
PubMed1994

Rapid behavioural and morphological responses of hydropsychid larvae (Trichoptera, Hydropsychidae) to sublethal cadmium exposure.

Larvae of Hydropsyche contubernalis and H. siltalai were exposed to sublethal cadmium concentrations of 0, 0.012, 0.16 and 10 mg/litre(-1) for 72 h. Linear logit models revealed a significant increase in the frequency and degree of damage of the anal papillae of both species with increasing Cd concentration. Hydropsyche contubernalis showed a stronger and earlier anal papillae response under Cd exposure than H. siltalai, whereas in the latter species darkening of the ventral sides of the abdomen was also observed. The lowest Cd level altered the competition behaviour of Hydropsyche contubernalis larvae after only 24 h exposure, yet no visual signs of morphological damage were detected. The exposure intruder larvae spent significantly less time trying to enter the nets of resident larvae than did unexposed intruders. In addition, both the exposed intruders and exposed residents pursued different behavioural tactics during the encounters compared to their unexposed counterparts.

Journal Article↗