Interspecific variation in temperature dependence of egg development of five congeneric stonefly species (Protonemura Kempny, 1898, Nemouridae,Plecoptera)

Embryonal development of the five congeners Protonemura auberti Illies, 1954, P. hrabei Rauser, 1956, P. meyeri (Pictet, 1841), P. nitida (Stephens, 1835), and P. praecox (Morton, 1894) was studied under various laboratory temperatures and different photoperiods.Mean number of eggs in field collected batches was between 470 (P. praecox) and 1211 (P. auberti). Spring species had smaller egg batches than autumn species (Table 1). Mean hatching success in the laboratory was 50–100% at 2–18 °C. In most species hatching success decreased slightly with increasing temperature (Figs. 1a-e). None of the eggs incubated at 24 °C developed. Hatching pattern followed an asymmetric frequency distribution. In general, the hatching periods were the shorter the higher the incubation temperature.Embryonic development of all five species was inversely temperature dependent (Figs. 2a-e), and well described by a power law relationship (Figs. 3a-e). Interspecific differences in incubation periods were notable at nearly all temperatures (Fig. 4). There was a distinct interspecific sequence in length of incubation period (with steps of about 4 days), which was the same as can be seen in the flight periods: The later the species flies the longer the incubation period. Temperature fluctuations and variations in photoperiod had no influence on incubation and hatching periods or hatching success.The thermal demand of the egg stage neither explains the recent geographical distribution of the Protonemura species, nor does it directly correspond to the field temperatures common during their egg development. However, it is optimal in respect to resource partitioning between the five species, with the consequence of temporal displacement of life cycles.Derived from Brittain's (in press) proposal to compare the two constants a and b of the regressions describing the temperature dependence of embryonal development, a new index (Integral Development Time, IDT) indicating the thermal demand was created for easier comparison of numerous species (Table 2). Evaluation of the IDT for various species of Plecoptera (Fig. 5) suggests that species belonging to the family group Systellognatha generally have higher thermal requirements in the egg stage than species belonging to the Euholognatha.     

The Group of Amphinemura flavostigma (Plecoptera,Nemouridae)

Three closely related species from Japan are treated and defined as composing the Amphinemura flavostigma group (Okamoto, 1922). One species, A. nikkoensis, is described as new to science. Two already known species, A. flavostigma and A. monotuberculata (Kawai, 1956), are redescribed, while the female of the latter is described for the first time. Another species, A. tetraspinosa Kawai, 1960, is regarded as a subjective synonym of Nemoura flavostigma Okamoto, 1922.     

Life History of a Population of Protonemura intricata (Ris, 1902) (Insecta,Plecoptera) in a Constant Temperature Stream in Central Europe

The nymphal biology (life cycle, secondary production and feeding) of a population of Protonemura intricata was studied in a calcareous stream with almost constant temperature (7–8 °C) through the year at Prosiek valley (Chočské Vrchy Mts., West Carpathians, Slovakia). The results were compared with those previously known for this species in other areas. According to our data, the species has a complicated life cycle consisting of two cohorts with different duration (probably a cohort splitting). This life cycle seems to be uncommon among the Plecoptera, which usually has simple univoltine or semivoltine life cycles, and could be probably attributed to the constant temperature regime similar to that of tropical environments. One factor, the photoperiod length, was positively correlated with monthly growth rates. The nymphal growth varied throughout the year, but the highest growth was in late spring and summer, and the lowest was in winter. The annual secondary production was very high (909.4 mg · m^–2) despite not being the most frequent taxon in the stream. The highest monthly production values were observed in the autumnal‐winter period (November–December) due to massive hatching of nymphs. The lowest production values were observed in late summer and early autumn. Analyses of gut contents showed that this species behaves mainly as gatherer‐collector, but also as shredder and, occasionally, as scraper. Changes in the gut content composition were detected in relation to the size. Comparing our results with those of the literature, it can be inferred that different populations of P. intricata can show notable differences in their life history when inhabiting places with different thermal conditions. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Notes on Plecoptera (20) Protonemura towadensis (Kawai, 1954)

The genitalia of the male holotype of P. towadensis (from Honshu) are illustrated. The distinction from P. ermolenkoi Zhiltzova, 1982 (from Sachalin and the South Kurile Islands) is discussed.     

Life histories of Nemouridae and Leuctridae in Southern Ontario (Plecoptera)

The life-histories of seven species of Nemouridae and two of Leuctridae have been investigated in Southern Ontario. Eleven sampling stations were chosen to illustrate the range of temperature conditions found in local streams.The Nemouridae and Leuctridae make up most of the stonefly fauna of the upstream cooler stations, but their numerical importance decreases considerably downstream.There is a definite seasonal succession of the species: Soyedina aallicularia, Prostoia completa and Shipsa rotunda appear in late spring, Nemoura trispinosa, Amphinemura delosa} and A. nigritta in early summer, Leuctra tenuis in midsummer and A. linda in late summer. L. ferruginea emerges throughout most of the summer, at least in the headwater streams.All the species are univoltine, except L. ferruginea which is usually semivoltine. Most Nemouridae, A. spp., P. completa and S. rotunda undergo a long embryonic diapause, whereas N. trispinosa and S. vallicularia develop directly. The nymphal development of N. trispinosa was compared in three streams; although the general pattern is similar, the growth is much more synchronized in the warmest station. There appears to be 16 nymphal instars in this species. L. ferruginea was common in seven stations; in the coolest, the life-cycle lasts two years, but in the warmest, many specimens succeed in completing their cycle in one year.

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Résumé Les cycles vitaux de sept espèces de Nemouridae et deux espèces de Leuctridae ont été étudiés dans onze ruisseaux du Sud de l'Ontario; ces stations d'échantillonnage représentent la gamme des températures des ruisseaux de cette région.Les Nemouridae et les Leuctridae constituent la majeure partie de la faune des Plécoptères dans les stations froides de l'amont. Cependant, leur importance décroît de façon significative dans les stations plus en aval.On reconnaît une succession bien définie des espèces durant l'année: Soyedina aallicularia, Prostoia completa et Shipsa rotunda apparaissent à la fin du printemps, Nemoura trispinosa, Amphinemura delosa et A. nigritta au début de l'été, Leuctra tenuis au milieu de l'ete et A. linda à la fin de l'été. L. ferruginea emerge pendant presque toute la saison chaude, du moins dans les stations de l'amont.Toutes ces espèces sont univoltines, sauf L. ferruginea qui est ordinairement semivoltine. La plupart des Nemouridae, soient A. spp., P. completa et S. rotunda doivent compléter une longue diapause embryonnaire, alors que N. trispinosa et S. vallicularia se développent directement. On a comparé la vie larvaire de N. trispinosa dans trois ruisseaux: bien que l'essentiel de la biologie soit semblable dans les trois cas, on remarque un plus grand synchronisme de la croissance dans la station la plus en aval. Il semble y avoir 16 stades larvaires chez cette espèce. L. ferruginea était abondante dans sept stations; dans la plus froide, le cycle vital dure deux ans, alors que dans la plus chaude, plusieurs specimens arrivent a boucler leur cycle en un an.

     

Food preference, growth and maturation of Nemurella pictetii (Plecoptera: Nemouridae)

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.     

The relative importance of temperature and diet to larval development and adult size of the winter stonefly, Soyedina carolinensis (Piecoptera: Nemouridae)

SUMMARY. 1. Soyedina carolinensis Claassen, a leaf shredding stonefly, was reared in a series of three laboratory experiments from early instar to adult on different species of deciduous leaves and at various constant and fluctuating temperature regimes.
2. Experiment 1, which involved rearing larvae on fourteen different leaf diets at ambient stream temperatures, showed that diet significantly affected larval growth and adult size but did not affect overall developmental time.
3. Experiment 2, which involved rearing larvae on five different leaf diets at each of three fluctuating temperature regimes (viz ambient White Clay Creek (WCC), ambient WCC+3°C, and ambient WCC+6°C), showed that: (i) adding 6°C to the normal temperature regime of WCC was lethal to 99% of the larvae regardless of diet; and (ii) warming WCC by 3°C did not affect developmental time but did significantly reduce adult size relative to adults reared at WCC temperatures on certain diets.
4. Experiment 3, which involved rearing larvae on five different leaf diets at each of five constant temperatures (viz 5, 10, 15, 20, 25°C), showed that: (i) temperature significantly affected the mortality, growth, and development time of larvae whereas diet only affected larval growth and mortality; (ii) temperatures at or near 10°C yielded maximum larval growth and survival for most diets; (iii) at 5°C, larval mortality was high and growth was low resulting in a few small adults for most diets; (iv) larval mortality was at or near 100% at 15°C regardless of diet; and (v) no larvae survived at 20 and 25°C.     

Protonemura berberica,a New Species of Nemouridaefrom North Africa (Plecoptera)

Protonemura berberica sp. n. is described from the Rif mountains (Morocco, North Africa). This species belongs to the Protonemura corsicana group, which has a circum-mediterranean distribution. The male is clearly distinguished by the shape of the epiproct, with its very short terminal filament which is directed upwards, and by the shape of the paraprocts.     

Plurimodal emergence and plurivoltinism of Central European populations of Nemurella pictetii (Plecoptera: Nemouridae)

Summary Nemurella pictetii Klapálek, 1900 (Plecoptera: Nemouridae) has bi-or trimodal emergence patterns in Central Europe. The emergence threshold temperature is about 8°C. Egg development is direct. The slopes of regressions describing its temperature dependence do not differ significantly between English, Norwegian and German populations, but the intercepts (i.e., the incubation period at 0°C) do. Regular sampling of a benthic population near Schlitz, in Hesse, West Germany, showed that part of the offspring of the first emergence group grew quickly and produced a second emergence peak. The remaining offspring of the first generation grew more slowly and overwintered, together with the offspring of the second emergence peak. This population exhibits partial bivoltinism. The potential for bivoltinism was also shown in laboratory rearings of a German population at a constant 14°C: many eggs yielded normal adults after about 120 days. Larval growth rates were up to 2.2% body length day^-1, much higher than for English Nemurella (unimodal emergence), or any other stonefly. The thermal sum (degree-days above 0°C) accumulated between the two emergence peaks, at the German sites studied, resembled cumulated degree-days in a laboratory culture. For an Austrian population with trimodal emergence, degree-days accumulated in the field were lower, suggesting a lower temperature demand and partial trivoltinism. This is the only case of confirmed plurivoltinism in Plecoptera. Nemurella pictetii seems to have lost seasonal life cycle cues, enabling the opportunistic use of favourable local conditions. Population synchrony appears to be regulated by the thermal demand for development and the emergence threshold temperature.     

新疆倍叉(虫责)属一新种记述(襀翅目:叉(虫责)科)

本文记述了采自新疆喀纳斯的倍叉[虫责]属Amphinemura 1新种：环齿倍叉[虫责]Amphinemura tricintusidens Wang＆Zhu,sp．nov。根据肛侧突中叶端部有3或4个环绕的小齿和肛上突背骨片端部形成的圆形腔可将该新种与其它种类相区别。正模♂,新疆喀纳斯,2005-Ⅷ—01,朱江艳等采。副模1♂,采集资料同正模。新种的模式标本保存在扬州大学昆虫标本馆。     

Hatching time and growth of Nemurellapictetii (Plecoptera: Nemouridae) in the laboratory and a Lake District stream

SUMMARY. 1. Nemurella pictetii Klapæplek took 2 years to complete its life cycle in both the laboratory and a small stream in the English Lake District.
2. Hatching time (days after oviposition for 10%. 50% and 90% of the eggs to hatch) and hatching period (days between dates for 10% and 90% hatched) decreased with increasing water temperature in the laboratory, and the relationships were well described by a power-law. Estimates of the mean time for 50% hatching in the stream varied between 16 and 31 days after oviposition. depending on temperature.
3. Larval instars numbered fifteen for males and seventeen for females with a constant ratio of 1.18 between successive instars (conformed with Dyar's rule). Larval growth was exponential at four constant temperatures in the laboratory; mean instantaneous growth rates were 0.40±0.01% day⁻¹ at 5.9°C, 0.43±0.01% day⁻¹ at 8.2°C, 0.46±0.01% day⁻¹ at 12. 1°C. 0.56±0.02%day⁻¹ at 19.8°C. No larvae survived after instar XI at 19.8°C.
4. Larval growth was exponential in the stream and was scarcely affected by variations in water temperature (range 4.2 -14.0°C); mean growth rates for three year-classes were 0.41±0.02, 0.43±0.08, 0.54±0.05% day⁻¹. Their similarity to laboratory growth rates under optimum conditions suggests that the availability of resources, such as food and space, was not restricting growth in the stream.     

Effect of environmental embryonic temperature on larval development of Macrobrachium rosenbergii (De Man)

Berried females of Macrobrachium rosenbergii (De Man) from Anuenue stock were allowed to incubate their eggs at three different temperatures (25,29, and 31°C). The newborn larvae were reared in the laboratory from hatch through completion of the metamorphosis to postlarva in 30 combinations of temperature (22–34° C) and salinity (0–34 ppt). Survival and stage attainment rates were observed. Multiple linear regression analysis and response surface methodology were used to estimate the response of larvae to these different temperature and salinity combinations. Dissimilarities in the response of zoeae from the three egg incubation temperatures were found. Larvae from eggs incubated at 25° C during embryonic development showed tolerance to a broader range of temperature and salinity conditions than those incubated at 29 or 31 °C. The response also changed with the ontogeny of the larvae. The zoeae are considered to have undergone acclimation during embryonic development, thus eliciting a different response.     

Oocytes develop from interconnected cystocytes in the panoistic ovary of Nemoura sp. (Pictet) (Plecoptera : Nemouridae)

The 2 ovaries of Nemoura sp. (Plecoptera : Nemouridae) are comb-like and house about 60–70 ovarioles each. By ultrathin serial sections through a whole ovariole of a last-larval instar, we gathered information on its ultrastructure and 3-dimensional architecture. The germarial region contains several clusters of interconnected oogonia or oocytes. The intercellular bridges (ring canals) are filled with fusomes. Most of the fusomes assemble to polyfusomes and some of the intercellular bridges move together and their cells assemble to rosettes. Results indicate that existence of polyfusomes is not sufficient for rosette formation. The oogonia or oocytes of each cluster develop synchronously. Oocytes detach from clusters next to intercellular bridges. A transdetermination of oogonia to nurse cells does not occur. Thus, the stone flies remain true panoists.     

Life history plasticity of Nemoura trispinosa (Plecoptera: Nemouridae) along a permanent-temporary water habitat gradient

1. The life history of the small herbivorous stonefly Nemoura trispinosa Claassen was studied in a variety of small springs in southern Ontario, Canada. Nymphs generally were able to tolerate a wide range of environmental conditions and were found in 78% of habitats sampled, although population densities differed markedly. 2. Life-cycle patterns varied from a univoltine, slow seasonal type to a univoltine, fast seasonal type with extended egg development. In one, highly stable, spring the life cycle was semivoltine. Inter-year variation was studied for 5 years in one spring and was found to be low relative to among-spring variation. 3. Differences in the life history traits of N. trispinosa populations from our spring series were most probably an expression of phenotypic plasticity rather than of genetic differentiation. 4. Maximum annual water temperature was the factor most influential on nymphal growth rate (non-linear relationship), whereas range in generation time was related to the degree of habitat permanence.     

A New Species of Mesonemoura from Yunnan: Mesonemoura sbordonii sp.n. (Plecoptera: Nemouridae)

Mesonemoura sbordonii, a new species of Nemouridae (Plecoptera) from Yunnan (China) is described. Remarks on its relationships with the closest species, M. vaillanti, are given.     

Effects of temperature on embryonic and early larval growth and development in the rough-skinned newt (Taricha granulosa)

We investigated the effects of temperature on the growth and development of embryonic and early larval stages of a western North American amphibian, the rough-skinned newt (Taricha granulosa). We assigned newt eggs to different temperatures (7, 14, or 21 °C); after hatching, we re-assigned the newt larvae into the three different temperatures. Over the course of three to four weeks, we measured total length and developmental stage of the larvae. Our results indicated a strong positive relationship over time between temperature and both length and developmental stage. Importantly, individuals assigned to cooler embryonic temperatures did not achieve the larval sizes of individuals from the warmer embryonic treatments, regardless of larval temperature. Our investigation of growth and development at different temperatures demonstrates carry-over effects and provides a more comprehensive understanding of how organisms respond to temperature changes during early development.     

The effect of temperature on embryonic and yolk-sac larval development in the burbot Lota lota

The present study investigated the effect of various temperature regimes on embryonic and yolk-sac larval development of the burbot Lota lota. At constant temperature regimes a high percentage of ready-to-hatch embryos, hatched larvae and normally shaped larvae was observed at the lowest temperature (2° C), which significantly decreased with increasing temperatures (4 and 6° C). No larvae hatched at 9° C. The stream temperature regime had no effect on the percentage of ready-to-hatch embryos, but significantly decreased the percentage of hatched larvae and of normally shaped larvae. The lake temperature regime did not affect the viability variables. Also an abrupt temperature increase from 2 to 4° C after 8 days and from 2 to 9° C after 48 days had no effect on the evaluated viability variables. For yolk-sac larvae no temperature related mortalities or abnormalities were observed between 2 and 9° C.     

The embryonic development of larval muscles in Drosophila

Each of the abdominal hemisegments A2-A7 in the Drosophila larva has a stereotyped pattern of 30 muscles. The pattern is complete by 13 h after egg laying, but the development of individual muscles has begun with the definition of precursors at least by the onset of germ band shortening, some 5.5 h earlier. The earliest signs of muscle differentiation are cell fusions, which occur in the ventralmost mesoderm overlying the CNS and at stereotyped positions in the rest of the mesoderm as the germ band shortens. At the end of shortening, the pattern of muscle precursors produced by these fusions is complete. Precursors filled with dye reveal extensive fine processes probably involved initially in cell fusion and, subsequently, in navigation over the epidermis to form attachment points. The muscle pattern is formed before innervation and without cell death. Thus, neither of these processes is involved in determining the distribution of precursors. Evidence is presented for the view that the development of the larval muscle pattern in Drosophila depends on a prior segregation of founder cells at appropriate locations in the mesoderm with which other cells fuse to form the precursors.     

Temperature‐Dependent Growth and Life Cycle of Nemoura sichuanensis (Plecoptera: Nemouridae) in a Chinese Mountain Stream

Plecoptera constitute a numerically and ecologically significant component in mountain streams all over the world, but little is known of their life cycles in Asia. The life cycle of Nemoura sichuanensis and its relationship to water temperature was investigated during a 4‐year study in a headwater stream (known as the Jiuchong torrent) of the Xiangxi River in Central China. Size structure histograms suggest that the life cycle was univoltine, and the relationships between the growth of Nemoura sichuanensis, physiological time, and effective accumulated water temperature were described using logistic regressions. The growth pattern was generally similar within year classes but growth rates did vary between year‐classes. Our field data suggest a critical thermal threshold for emergence in Nemoura sichuanensis, that was close to 9 °C. The total number of physiological days required for completing larval development was 250 days. The effective accumulated water temperature was 2500 degree‐days in the field. Development during the life cycle increased somewhat linearly with the physiological time and the effective accumulated water temperature, but some non‐linear relationships were best developed by logistic equations. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)