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Summary 1. The stonefly Nemurella pictetii has a highly variable life cycle and is semi- and uni-, but also plurivoltine in different geographical areas. 2. The influence of the type of food on growth and maturation of larvae was studied in laboratory experiments. Food preference was also assessed. 3. Larvae of N. pictetii are strongly opportunistic feeders utilising a broad range of food sources. However, biofilm was preferred over detritus (conditioned leaves), green algae and animal food. The highly mobile larvae quickly found the preferred food. Larvae fed on biofilm grew and developed significantly faster than larvae fed on conditioned leaves. 4. Larval growth and maturation in experiments as well as in the field differed with available food qualities. Phases of faster growth and maturation corresponded well with maximum availability of biofilm in the field. This contributes to the interpretations of differences in life cycles in the field.

Life cycle, survival and production of the univoltine midge Ptychoptera paludosa whose larvae live in fine sandy sediments were studied in a German stream (1989-1990). Growth of the 4th larval instar was linear. Adults emerge from May, for ca 8 weeks (1985-1990); emergence was 0.56 g dry weight m -2 lentic area (1990). Density decreased strongly only when larvae were young; except after an exceptional spate, numbers emerging were independent of discharge. Larval survival was ca 9%; only 10% of the potential offspring of the survivors actually appeared in the next generation. Secondary production (P) was 2.3 g ash free dry weight (AFDW) m -2 y -1 , mean biomass (B) was 0.6 g AFDW m -2 , i.e., the P/B ratio was 3.8.

A taxonomic treatment of the Australian net-winged midges (Diptera: Blephariceridae) of the tribe Apistomyiini is presented. Characters supporting the monophyly of the tribe are described and illustrated. New taxa are Theischingeria rieki gen. et sp. nov., Parapistomyia mueller sp. nov. and Parapistomyia bulbifera barringtoniana ssp. nov., bringing the total number of Australian Apistomyiini to eight species and subspecies in four genera. the New Guinean Curupirina papuana Zwick and Hortle is transferred to the Australian genus Parapistomyia Zwick; its adult and pupa are described. A morphocline between the two Australian species of Apistomyia is described. New keys to larvae, pupae and adults of all Australian Apistomyiini are presented. the phylogenetic relationships within the tribe are discussed.

1. We examined selected aspects of the nutritional ecology of larval Ptychoptera paludosa and their role in nutrient cycling in the Breitenbach, a first-order stream in Hesse, Germany. 2. Food preference experiments demonstrated significant preference for sediments with a high organic matter content and live bacteria. 3. pH was circumneutral in all sections of the gut. 4. Enzymatic activity (β-glucosidase and amino-peptidase) in different parts of the gut was measured using 4-methylumbelliferyl-β-D-glucopyranoside (MUF-Glc) and leucine-4-methylcoumarinyl-7-amide (Leu-MCA). β-glucosidase activity was highest in the hindgut. 5. The mean larval gut passage time was between 7 and 8 h. 6. The egestion rate of last instar larvae was about 0.35 mg dry weight (DW) faeces per larva h–1 and about 1.25 mg ash-free dry weight (AFDW) faeces per mg larval AFDW day–1. 7. Larval faeces contained at least 4–18 times more organic matter than the average in the sediments in which they were feeding, that is, larvae fed selectively, extracting organic matter from sediments. 8. P. paludosa larvae are important in the dynamics of detritus in slow-flowing reaches of the Breitenbach. They gather organic material from the sediment to a depth of 3 cm, and release it as faeces onto the sediment surface. A total of 770 g DW faeces m–2 yr–1, comprising about 16% organic matter, was produced by the Ptychoptera population.

1. Temperature dependence of egg development of Dinocras cephalotes (Curtis) (three German and one Norwegian population) and Slovenian D. megacephala (Klapalek) was studied under a constant 14 : 10 light : dark photoperiod and constant temperature ranges of 4–24 °C and 4–18 °C, respectively. D. cephalotes was also incubated under seasonal field conditions; natural daylength and fluctuating temperatures had no modifying effect. 2. Both species have very similar lower threshold temperatures (4 and 3.5 °C, respectively), thermal demand for development (c. 600 degree days) and high dependence of mean incubation period on temperature (exponents of regressions near 1.5). Present data on D. cephalotes agree with the literature on British and Norwegian material of the same species. 3. Development occurs only at cue temperatures above the lower threshold. Cue temperatures range from 6 °C (some D. megacephala) to 14 °C (some D. cephalotes) and vary strongly within and between egg masses of D. cephalotes. Variation is not random, but seems to be genetically determined. 4. The variable temperature response renders study of effects of particular experimental regimes, and comparisons between local populations, difficult. 5. A latitudinal gradient in cue temperatures for development from 6 °C at c. 46 °N to 12 or even 14 °C at c. 61 °N seems to reflect reduced diversity at high latitudes. 6. Average success of spontaneous hatching exceeded 90% between 12 and 20 °C, but declined towards higher and lower temperatures. 7. Unhatched eggs were not dead but in parapause; development at other, higher or lower, temperatures was induced. Spontaneous plus induced hatching success approached 90%. Developing eggs rarely died; most dead eggs were apparently unfertilized. 8. Dormant plecopteran eggs are proposed to form a seed bank in stream bed sediments. Highly successful development after up to 220 days of dormancy was ascertained in Dinocras, and survival for up to 3 years is reported for other Perloidea. 9. Only systellognathan egg morphology provides options for long dormancy; the other plecopteran superfamilies, notably Nemouroidea, follow different strategies.

Die Struktur von Fliesgewasser'-Okosystemen ist zu komplex, um die okologischen Zusammenhange auf wenigen Seiten umfassend darzustellen. Stattdessen soll anhand weniger Beispiele aktueller Grundlagenforschung gezeigt werden, wie abiotische, mikrobiologische und verschiedene andere biologische Fliesgewassern zusammenwirken mussen. Am Beispiel des Eintrags gelosten organischen Materials mit dem Grundwasser, aber auch an den terrestrischen Populationsverluste von Wasserinsekten wird gezeigt, das man okologische Prozesse in Fliesgewassern nur dann verstehen kann, wenn man deren besonders enge Wechselbeziehungen mit dem terrestrischen Umland, ihren Einzugsgebieten, beachtet. Diese enge Vernetzung mit dem Umfeld hat auch eine besondere Verletzlichkeit von Fliesgewassern zur Folge.

SUMMARY 1. The mortality of Baetis vernus Curtis and Baetis rhodani Pictet during the terrestrial-aerial and aquatic life stages was studied at the Breitenbach near Schlitz, Hesse, Germany. The number of females emerging from the stream was recorded with emergence traps. To estimate mortality of females of both species during terrestrial life, numbers of emerging females were compared with numbers of females returning to the stream for oviposition, as shown by numbers of egg masses found in the stream. 2. Mortality of female B. vernus during their terrestrial life stage was 98.8%. It was 91.2 and 96.6%, respectively, during the first and second generations of B. rhodani. 3. To estimate the mortality of both sexes of B. rhodani during the aquatic life stage, the number of eggs laid by the first generation was compared with the number of adults emerging during the second generation. 4. Mortality during the aquatic phase (both sexes combined) of B. rhodani was 91.1%. 5. Mortality during the terrestrial life stages was at least as high, if not higher than during the aquatic stages. Evidently, there is a considerable export of organic material into the terrestrial environment around the stream. Mortality during terrestrial life may be an important regulator of population size.

SUMMARY. 1. Egg development and larval growth of Protonemura intricata (Ris, 1902) (Plecoptera: Nemouridae) were studied in the laboratory and in the Breitenbach, a small stream-in Germany (F.R.G.). 2. The mean number of eggs in batches collected from the field was 627 (S=314). 3. Mean batching success in the laboratory was 60–100% at 2–18°C. Cumulative hatch in individual batches could be described by asymmetrically sigmoid curves. The length of the hatching period was positively correlated with the length of the incubation period. 4. The incubation period of I', intricata normally consists of an initial dormancy followed by subsequent development. The length of embryonic development (Y. days) is strongly inversely temperature (T, °C) dependent and can be described by the equation: 5. The length of dormancy is dependent on oviposition dale, and is shorter the later that the eggs are laid. It also depends on temperature during incubation and is increased by rising temperatures. As a consequence, larvae hatch more or less synchronously in the field during autumn. Total incubation period, i.e. dormancy and actual development, exhibits a complex dependence on both incubation temperature and oviposition date. Under constant laboratory temperatures, a late sharp fall in temperature can terminate dormancy earlier. 6. Photoperiod probably induces dormancy and may already act on the last larval instars of the parent generation. The dormancy of P. intricata is classified as an oligopause (Muller. 1970, 1976). 7. In the laboratory. P. intricata larvae from early batches with long dormancy grew faster than larvae from late batches with direct development. Final size was the same in both cases. This acted against the population synchrony induced through egg dormancy. Benthos samples suggest the same in the field. 8. Avoidance of the suboptimal summer conditions in streams by the cold stenothermous P. intricata is suggested to partly explain the success of the species, which contributes more to total emergence biomass than do other Plecoptera in the Breitenbach.

Summary To estimate annual production, Hamilton (1969) initially calculated mean losses/sample, as did Hynes (1961) and Hynes & Coleman (1968). While the latter failed to convert these means to annual production, Hamilton has overcome this problem by assuming a population at equilibrium. Then, production may be calculated by multiplying mean losses with the number of classes through which specimens can grow. The method was claimed to be suitable for unidentified material and not to depend strongly on growth patterns; both claims are refuted here. The main objection is that for calculations, populations must be divided into fractions. While equilibrium might be acceptable for an entire population, it is not for any of its fractions. The particular conversion factor therefore has no justification and the method becomes inapplicable.

The genus Phanoperla (=Dyaperla Banks, 1939) (Plecoptera: Perlidae: Perlini) is revised and generic diagnoses are provided for adults and larvae. Diagnostic and constitutive characters of the tribe Neoperlini are discussed, and Chinoperla Zwick, 1980, is shown to be the closest relative of Phanoperla. Many past misidentifications of Phanoperla species have been corrected by the use of characters recently recognized as important, namely the structure of the internal genitalia of male and female specimens and particularly the complex pattern of spines on the male penial sac made visible by eversion of this structure, and details of sculpturing of the egg chorion. The following species of Phanoperla are recognized: amorpha sp.n.; anomala (Banks, 1939); bakeri (Banks, 1924); ceylonica Kawai, 1975; comuta sp.n.; flaveola (Klapalek, 1921), comb.n. (=clarissa (Banks, 1913), syn.n.), (=Neoperla hageni Banks, 1920, syn.n.), (=N.consimilis Banks, 1924, syn.n.); guttata sp.n.; himalayana Zwick, 1977 (=siwalika Harper, 1977); limosa (Hagen, 1858); maculata sp.n.; maindroni (Navas, 1926), comb.n.; malayana sp.n.; minutissima (Enderlein, 1909); nana sp.n.; nervosa Banks, 1939; nuwara Kawai, 1975; omega sp.n.; pallipennis (Banks, 1938); parva sp.n.;pumilio (Klapalek, 1921), comb.n.; peniculus Kawai, 1969a; schmidi sp.n.; sertispina Jewett, 1975; srilanka sp.n.; sumatrae sp.n.; testacea (Hagen, 1858); wedda sp.n. P.claggi (Banks, 1938) is a nomen nudum. All species are (re-)described and figured; all primary types have been examined. A key to species is provided. Most species can be assigned to one of seven species groups which are defined. Phanoperla is endemic to the Oriental Region. Species groups are generally widespread, but individual species are in most cases known only from restricted areas.

Study of numerous adults was done for 5 species of Neoperla taken in an emergence trap on the stream Kalengo, Republic of Zaire, over 16 months (table 1). Taxonomic characters are evalutaed considering individual variation and variation between disjunct populations. The assumption by previous authors of only 1 variable species of Neoperla in Africa is refuted. Some bionomic data for the 2 common species in the material are presented. Biomass (dry weight) is 462.4 mg/m2/yr or 12% of total biomass of emerging insects (BOTTGER 1975). Close agreement with figures reported for European streams (ILLIES 1971) may be accidental as biocoenotic structures are very different.