Species Of Hydropsyche Research Articles

Ecological Segregation of Two Species of Hydropsyche (Trichoptera: Hydropsychidae) in a European Second-Order Stream (Essonne, France)

ABSTRACT Life-history patterns and food habits are described for two sympatric species of Hydropsyche (H. pellucidula and H. contubernalis) sampled for 15 months in a second-order stream, the Essonne (France). Both species showed univoltine life-cycles with remarkable differences in winter. H. contubernalis overwintered mainly in the 4th or 5th larval instar; whereas, the more abundant H. pellucidula overwintered in the 2nd or 3rd larval instar. The main larval growth periods of the two species were also different, and this could be due to ecological segregation, which allows both species to share a similar ecological niche. The two species shared the same food habits throughout all larval instars; however, they both changed their food habits as they passed from one instar to another, and earlier instars were more predatory than the older ones.

Genetic diversity in some species of hydropsyche (trichoptera, hydropsychidae) in central and southern Italy

The genetic differences in 32 populations of Hydropsyche belonging to nine species distributed in Sicily, and central and southern Italy were assayed by horizontal starch gel electrophoresis. Larval specimens were examined. Twelve enzyme loci were assayed and allele frequencies, variability parameters, and Nei's genetic distance were calculated. The percentage of polymorphic loci ranged from 8.3 to 50.0%, the mean number of alleles per locus from 1.1 to 1.8, and the mean observed heterozygosity from 0.009 to 0.123. Nei's genetic distances values between conspecific populations ranged from 0 to 0.096; in the comparison between populations from Sicily and Calabria, H. doehleri had the highest values. Only for H. spiritoi there were differences among the Sicilian populations. From genetic distance data, a dendrogram was obtained. At interspecific level, the values of genetic distance between conspecific populations ranged from 0.201 {H. spiritoi ‐ H. gereckei) to 1.135 (H. dinarica ‐ H. klefbecki). Genetic data were in agreement with morphological data.

Waiting for Hydropsyche - Why has only one of at least four local Hydropsyche species returned into the Lower Rhine River?

Waiting for Hydropsyche - Why has only one of at least four local Hydropsyche species returned into the Lower Rhine River?

Net-Building Behaviour of Six Hydropsyche species (Trichoptera) in Relation to Current Velocity and Distribution along the Rhône River

A longitudinal succession of species of Hydropsyche along a stream continuum is a common pattern in Palearctic as well as in Nearctic regions. Using a laboratory channel, we studied the relationship between current velocity and six Hydropsyche species distributed from small streams to large rivers in the Rhone Basin (France). Different phases of net-building behaviour were used to test the reactions of larvae to variations in current speed over a range of 4-40 cm/s. Hydropsyche angustipennis had more than 30% of its larvae wandering at the end of the experiment and was the least adapted species to the experimental conditions; the proportion of wandering larvae for the other five species was less than 10%. The largest proportion of catchnets with regular meshes occurred at velocities between 28 and 40 cm/s for the upstream species (H. siltalai and H. angustipennis) and for a species of the middle reaches of stream (H. pellucidula). Another middle-reach species (H. exocellata) had the highest proportion of ...

Stream continuum and metabolic rate in the larvae of five species of Hydropsyche (Trichoptera)

The effects of temperature on the metabolic rate of five species of Hydropsyche larvae belonging either to the rhithron (Hydropsyche dinarica, H pellucidula and H siltalat) or to the potamon (H contubernalis and H modesta) have been studied The total amplitude of the metabolic rate between 5 and 25°C is higher in the larvae inhabiting the potamon than those of rhithron (particularly in H siltalat and H dinarica) The shapes of the metabolism temperature curves (M/T curves) of H contubernalis and H modesta differ from each other, although they live in the same habitat and are closely related A comparison with some species of Gammarus suggests a relationship between metabolic rate and the variability of environmental conditions

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.

Variability in the life‐history patterns of four species of Hydropsyche (Trichoptera: Hydropsychidae) in southern Ontario streams

The life‐history patterns of four Hydropsyche species (Trichoptera: Hydropsychidae) found in the Credit and Humber Rivers of southern Ontario were investigated through rearing studies, larval and adult collections, and analyses of densities and mortality of field populations of pupae. Hydropsyche slossonae was univoltine but was probably capable of producing a second generation under favourable conditions at the warmest station at which it occurred. Hydropsyche sparna was partially bivoltine at upstream stations and bivoltine at downstream stations. At downstream stations, the common species were Hydropsyche bronta. which was trivoltine. and Hydropsyche morosa, which was bivoltine. Hydropsyche sparna, H. bronta and H. morosa all exhibited a split‐cohort development, in which not all of the summer‐produced larvae completed development, pupated and emerged before the end of the growing season. Overwintering populations consisted of young larvae that had hatched from eggs laid by adults of the previous generation. Analysis of the temporal changes in the densities of living and dead pupae provided a reliable way to separate overwintering and spring‐ and summer‐produced generations.

Life Cycles of Hydropsyche riola, H. slossonae and Cheumatopsyche pettiti (Trichoptera: Hydropsychidae) in a Spring-Fed Stream in Minnesota

Life cycles are presented for hydropsychid populations downstream of a small (0.06 ha) impoundment in a Minnesota trout stream where headwater springs maintained water temperatures between 2 and 16 C in 1982-1983. Hydropsyche slossonae Banks and Cheumatopsyche pettiti (Banks) were both univoltine with a long period of summer recruitment beginning in late June. These species overwintered mainly in the third and fourth instars and began to pupate the following May. Hydropsyche riola Denning hatched 1-2 weeks earlier and grew more rapidly in summer than the other species; some individuals matured within 2 months and may have produced a small second generation. Most of the H. riola population overwintered in the final instar and began to pupate the following April. The largely northern distribution of H. riola may have adapted it to such cool temperatures that the Valley Creek temperatures were relatively warm enough, especially in winter and early spring, to promote faster growth than is usually seen in North American species of Hydropsyche at equivalent

Food preferences in three species of Hydropsyche (Trichoptera)

Food preferences in three species of <i>Hydropsyche</i> (Trichoptera)

Cardiocladius (Diptera: Chironomidae) Larvae Ectoparasitic on Pupae of Hydropsychidae (Trichoptera)

Larvae of Cardiocladius sp. were found to feed on pupae of several species of Hydropsyche and Cheumatopsyche . The chironomid larvae enter the pupal cases after closure and feed on the immobile caddisflies, often consuming the host. In one collection, over 61% of all hydropsychid pupal cases contained Cardiocladius sp. larvae. This represents a very significant source of mortality for the caddisfly population.

Life history patterns of some species of Hydropsyche (Trichoptera: Hydropsychidae) in southern Ontario

Life history patterns are described for five species of Hydropsyche in the Credit and Humber rivers. Larvae of univoltine species matured in May or June. Bivoltine species had a fast-growing summer generation of larvae maturing in July or August and a slow-growing winter generation of larvae maturing in April or May. Hydropsyche betteni, H. dicantha, H. slossonae, and H. sparna were bivoltine at some sampling stations, univoltine at others. Hydropsyche scalaris was exclusively univoltine. Most species were represented by many instars concurrently during summer. Overwintering occurred in a smaller number of instars. Species that overwintered in the final or penultimate larval instar were more likely to mature early and to be bivoltine than species overwintering in younger instars. High summer water temperatures and (or) food quality increased growth rates and the probability that a summer generation could mature before fall. Smaller species were more likely to be multivoltine than larger species.Differences among the life cycles of the five species did not suggest effective ecological segregation in summer in terms of larval size. Different overwintering stages among the species may prove to be important factors controlling the number of generations per year.

Larval Identification and Instar Association in Some Species of Hydropsyche and Cheumatopsyche (Trichoptera: Hydropsychidae)

Features of hydropsychid larvae are described which allowed coexisting species in southern Ontario to be distinguished while in the 1st 3 instars; these young stages cannot usually be identified by existing taxonomic keys. Cheumatopsyche differed from Hydropsyche in having a long tapered seta on each antero-lateral corner of the pronotum. Species of Hydropsyche were distinguished according to the length and degree of tapering of the pronotal seta, by background color of head and thoracic sclerites, by round spots and oval patches on the dorsum of the head capsule, and by abdominal setae and scale hairs. After species had been differentiated, measurements of head widths showed that successive instars increased in size in a regular geometric progression (Dyar's Rule). The factor of increase was ca. 1.5 in all species. The use of Dyar's Rule is suggested as a taxonomic tool to associate young instars of coexisting hydropsychids with the more easily identified older instars.