Life Cycle of Himalopsyche japonica (Morton) (Trichoptera: Rhyacophilidae) in Two High Mountain Streams in Nagano, Central Japan

The life cycle of Himalopsyche japonica (Morton) was studied in two high mountain streams at about 1500 m a.s.l. from September 2000 to May 2002 in central Japan. The life cycles in both streams are univoltine. Larval development in upper streams with cooler water is slower than in lower streams with warmer water. The relationships between voltinism or larval size and water temperature are discussed.     

The Life Cycle of Lestes viridis (Odonata: Lestidae) in Two Seasonal Streams of the Sierra Morena Mountains (Southern Spain)

The life cycle of the zygopteran odonate Lestes viridis in two seasonal streams in the Sierra Morena Mountains is inferred from size-frequency analyses of handnet samples of larvae and records of presence and reproductive activity of adults during three consecutive years. The egg stage (duration 5–6 months) overwinters, larval development is brief (6–8 weeks) and adults undergo a protracted, prereproductive, summer diapause (up to 3 months) before mating and ovipositing in late September, about one week after the first appreciable fall of rain, but before surface water reappears in the streams after having been absent for about four months during the hot, dry summer. Comparison between this life cycle and those of more northerly populations reveals a latitude-correlated cline in phenology resembling that found in some other northern hemisphere odonates that, like L. viridis, maintain an obligatorily univoltine life cycle at different latitudes.     

Recolonization of estuarine organisms: effects of microcosm size and pesticides

Two six-week laboratory experiments were conducted to evaluate effects of pesticides and microcosm size on benthic estuarine macroinvertebrate recolonization. Sediments fortified with the pesticides (fenvalerate: controls, 5 (low) and 50 μg g⁻¹ wet sediment (high); endosulfan: controls, 1 (low) and 10 μg g⁻¹ wet sediment (high)) were fine-grained, organically rich (approximately 3.5% organic carbon and 22% dry weight) material. Relative dominance of the four most abundant taxa in both experiments was consistent among treatments with few exceptions. The amphipod,Corophium acherusicum, dominated abundance in both experiments. In the fenvalerate experiment, large trays (400 cm²) contained significantly (p<0.05) more total number of taxa (TNT) than small microcosms (144 cm²) but tray size was not significantly related to total number of organisms (TNO). When size was adjusted to a common unit area, small trays contained significantly more TNO than large containers. Adjusted abundance of small trays was 2.5 times that of large containers; a ratio close to that of microcosm sizes (i.e., 2.8). This result suggests that larval supply may have been inadequate to ‘aturate’ the available sediment in large containers. Fenvalerate significantly reduced abundance in the high treatment compared to both controls and low treatment but low treatment was not significantly different from controls. The amphipod,Corophium acherusicum, accounted for most of the decrease in abundance in response to fenvalerate. The holothruroid,Leptosynpta sp. and the polychaete,Mediomastus ambiseta, increased in abundance significantly with increased concentration of fenvalerate. Combined effects of actual microcosm size and concentration of endosulfan were not significant for TNO or TNT. As in the fenvalerate experiment, adjusted abundance of small microcosms was 2.6 times that of large trays which approximated the ratio of unit area between microcosm sizes. Abundance of a few taxa responded significantly to adjusted and unadjusted unit area. Abundance of the tunicate,Molgula manhattensis, increased significantly with increased concentration of endosulfan. Abundance was affected by sample location (e.g., interiorvs exterior cores) within microcosms. Abundance adjusted to unit area resulted in significantly greater TNO in externalvs internal cores. This has importance for sequential sub-sampling of microcosms to determine temporal dynamics. Statistically significant effects were measured in benthic community structure associated with microcosm size; however, the magnitude was relatively small. There appears to be no major biological reason to select one microcosm size over the other for screening for contaminant effects. Where feasible, the small trays provide savings in sample preparation and analysis, allow more replicates where laboratory space is limiting and generate less chemical waste. These benefits may be off-set by less ‘artifacts’ associated with edge effects of larger microcosms and the need for a larger mass of sediment to accommodate additional analytical requirements (e.g., thin vertical surficial samples to refine contaminant exposure at the sediment/water interface).     

Life cycles and growth rates of Baetis spp. (Ephemeroptera: Baetidae) in the laboratory and in two stony streams in Austria

SUMMARY. Larvae of Baetis alpinus, B. lutheri and B. rhodani were reared in a stream channel (water temperature range 4.2–11.4°C) in the laboratory. The larval growth was exponential and the mean specific growth rate varied from 1.93 to 2.24% day^?1 for B. alpinus, 1.49 to 3.41% day^?1 for B. lutheri and 0.79 to 3.11% day^?1 for B. rhodani. These variations in growth rate were related to variations in mean temperature and this was the major factor affecting growth in the laboratory. Non-quantitative samples of the benthos in the Seebach and Unterseebach, two stony streams near Lunz, Austria, were taken at approximately monthly intervals from November 1965 to May 1968. In each year, there were two winter and three summer cohorts for B. alpinus from Seebach and two or three winter and one to three summer cohorts for B. lutheri and B. rhodani from Unterseebach. Over the study period of 30 months, eleven cohorts were recorded for B. alpinus and B. lutheri, and ten cohorts for B. rhodani. The life cycle of a cohort varied from 3 to 8 months in B. alpinus, from 2.5 to 9 months in B. lutheri and from 2.5 to 8 months in B. rhodani. Mean specific growth rate in length varied from 0.82 to 2.97% day^?1 for B. alpinus, 0.96 to 3.33% day^?1 for B. lutheri and 0.65 to 3.01% day^?1 for B. rhodani. The percentage of the variability in growth rate accounted for by variations in mean temperature was 63% for B. alpinus, 91% for B. lutheri and 82% for B. rhodani. Therefore mean temperature was clearly the major factor affecting the growth rates in the field. An agreement was found between the growth rates of B. alpinus in the field and the laboratory. The growth rates of B. lutheri and B. rhodani were slower in the field than in the laboratory at higher temperatures. The possible reasons for this latter discrepancy are discussed, and the growth rates of the three Baetis spp. are compared with those of other species of Ephemeroptera.     

The life cycle and growth ofIsoperla grammatica andI. difformis (Plecoptera) in southernmost Sweden: intra- and interspecific considerations

Studies on the life cycle and growth ofIsoperia grammatica andI. difformis from eight southern Swedish streams demonstrated that the former species shows greater between-stream differences than the latter species.I. grammatica larvae had typically two periods of rapid growth, autumn and spring, whileI. difformis larvae grew mainly in autumn-winter. In one of the streams, however,I grammatica grew rapidly throughout all winter. Maximum larval size differed between streams, and so did the timing of the first appearance of nymphs and nymphal maturation. Temperature was probably the most influential factor explaining all these differences. While sexual dimorphism inI. grammatica is slight but significant, it is very prominent inI. difformis. The sizes of larvae overlapped little between species as well as sexes suggesting that intra- and interspecific competition was, or had been, important. InI. grammatica this reduced overlap was expressed in several size-classes of males and females successively replacing each other, resulting in a meandering pattern of the size distribution charts. There were additional indications of possible interactions, such as a significant negative correlation between the densities of the two species.     

Low levels of hybridization between sympatric Arctic char (Salvelinus alpinus) and Dolly Varden char (Salvelinus malma) highlights their genetic distinctiveness and ecological segregation

Understanding the extent of interspecific hybridization and how ecological segregation may influence hybridization requires comprehensively sampling different habitats over a range of life history stages. Arctic char (Salvelinus alpinus) and Dolly Varden (S. malma) are recently diverged salmonid fishes that come into contact in several areas of the North Pacific where they occasionally hybridize. To better quantify the degree of hybridization and ecological segregation between these taxa, we sampled over 700 fish from multiple lake (littoral and profundal) and stream sites in two large, interconnected southwestern Alaskan lakes. Individuals were genotyped at 12 microsatellite markers, and genetic admixture (Q) values generated through Bayesian‐based clustering revealed hybridization levels generally lower than reported in a previous study (<0.6% to 5% of samples classified as late‐generation hybrids). Dolly Varden and Arctic char tended to make different use of stream habitats with the latter apparently abandoning streams for lake habitats after 2–3 years of age. Our results support the distinct biological species status of Dolly Varden and Arctic char and suggest that ecological segregation may be an important factor limiting opportunities for hybridization and/or the ecological performance of hybrid char.     

Seasonal incidence of two co-occurring adult parasitoids of Acalymma vittatum in New York State: Centistes (Syrrhizus) diabroticae and Celatoria setosa

We report the incidence of striped cucumber beetle (Acalymma vittatum [Fabricius]) (Coleoptera: Chrysomelidae) parasitism in bi-weekly samples from diverse farm locations in central New York State over the course of two growing seasons. Two parasitoid species not previously verified in this geographic region were found: Celatoria setosa (Coquillett) (Diptera: Tachinidae) and Centistes (Syrrhizus) diabroticae (Gahan) (Hymenoptera: Braconidae). Parasitism by C. setosa, up to 43%, [mean 8.67%] was comparable to previously published rates. Contrary to the expectations of earlier authors, however, C. diabroticae was found to be ubiquitous and maximum rates of parasitism (~54%) were >threefold greater than the only other published report for this species [C. diabroticae mean 14.36%]. In laboratory assays, we investigated C. diabroticae larval development. We also tested the effects of wasp clone and host beetle sex on C. diabroticae larval development. This is the first documentation of life cycle information for this braconid.     

Naupliar development of Acanthodiaptomus denticornis (wierzejski, 1887) and Arctodiaptomus alpinus (Imhof, 1885) (Copepoda: Calanoida) and a comparison with other Diaptomidae

The six naupliar instars of the two alpine species Aconthodiaptornusdenticornis and Arctodiaptomus alpinus are described and illustrated.Their external morphology is compared with that of all presentlyknown diaptomid nauplii in an attempt to provide usehl taxonomiccharacteristics to identify larval diaptomids. The larval stagesof the two species are remarkably similar in size and overallappearance, and show an identical pattern of limb setation throughoutthe whole development. Diagnostic characters are mainly relatedto the differentiation of antennules and caudal armature.     

Life history differences of Psilotreta locumtenens (Trichoptera: Odontoceridae) in two reaches of a mountain stream in Korea

The life history traits of the caddisfly, Psilotreta locumtenens Botosaneanu (Odontoceridae), were studied in two stream reaches with different thermal ranges (main and branch streams) of the Gapyeong Stream, a typical mountain stream located in the central Korean Peninsula. Psilotreta locumtenens larvae were quantitatively sampled monthly from November 2008 to July 2010, and biweekly during the emergence period (late April to early July), using a Surber sampler (30 × 30 cm). Adults were quantitatively sampled with a sweep net. Larval density in the main stream (324.21 ± 38.59 m^?2) was higher than that in the branch stream (60.48 ± 10.86 m^?2). The larvae hatched in the early summer and overwintered as 5th and 3rd instars in the main and branch streams, respectively. The emergence peak at the main stream was approximately 2 weeks earlier. The sex ratio at both sites was approximately 0.3. The life history in both streams was univoltine. Secondary production in the main stream was much higher than in the branch stream, owing to high larval densities, and the P/B ratios at the two sites were similar. This study demonstrated remarkable differences in larval growth patterns and emergence peaks in P. locumtenens between the two stream reaches due to differences in accumulated degree days (230.30 DD) and other phenological cues such as daily mean threshold water temperature (9°C) during the ascending phase, despite their relatively small mean annual water temperature difference of 0.58°C.     

Instar sizes,life cycles,and food habits of five Rhyacophila (Trichoptera: Rhyacophilidae) species from the Appalachian Mountains of South Carolina,U.S.A.

The larval head widths at each instar, life cycles, and food habits of late instars were determined for five species of Rhyacophila from two Appalachian mountain streams in South Carolina, U.S.A. Rhyacophila acutiloba Morse & Ross was univoltine with two cohorts, one emerging in the spring and another presumably emerging in early autumn. Rhyacophila fuscula (Walker), R. nigrita Banks, and R. carolina Banks were apparently multicohort, univoltine species with extended flight periods. Rhyacophila minor Banks was univoltine with a spring emergence. All species were predaceous and consumed mainly Plecoptera nymphs and Trichoptera larvae.     

Life history traits of shrimps (Decapoda: Palaemonidae) of Amazonian inland waters and their Phylogenetic interpretation

Amazonian shrimps (Decapoda, Palaemonidae) of several genera from the generally nutrient‐poor, acid waters of the Rio Negro basin show two different breeding patterns: in the annually inundated (Jan./Feb. to Sept./Oct.) lowland forest (= “igapó") they breed during a period with rising and high water levels only (Dec. to July); in the headwater streams draining the “terra firme”; (= regions not subject to annual inundations), the same species breed continuously the year round. All species from these nutrient‐poor and hence, plankton‐deficient, waters have abreviated life cycles with 1–3 benthic larval stages; this includes several Macrobrachium species. However, Macrobrachium amazonicum from the plankton‐rich floodplain lakes, which are fed by the richer water of the Amazon river, maintains the marine pattern of development with numerous stages of filter‐feeding, planktonic larvae. Phylogenetic convergence (several genera developing independently the same adaptive pattern) and divergence (the same genus/species exhibiting different patterns in different environments) are discussed in relation to recent, general molecular genetics.     

Life cycle and host specificity of Amblyomma triste (Acari: Ixodidae) under laboratory conditions

We report biological data of two generations of Amblyomma triste in laboratory and compared the suitability of different host species. Infestations by larval and nymphal stages were performed on guinea pigs (Cavia porcellus), chickens (Gallus gallus), rats (Rattus norvegicus), rabbits (Oryctolagus cuniculus), wild mice (Calomys callosus), dogs (Canis familiaris) and capybaras (Hydrochaeris hydrochaeris). Infestations by adult ticks were performed on dogs, capybaras and rabbits. Tick developmental periods were observed in an incubator at 27 °C and RH 90%. Guinea pigs were the most suitable hosts for larvae and nymphs, followed by chickens. The remaining host species were less suitable for immature ticks as fewer engorged ticks were recovered from them. Mean larval feeding periods varied from 3.8 to 4.7 d between different host species. Mean larval premolt periods ranged from 8.9 to 10.4 d. Nymphal mean feeding periods varied from 4.2 to 6.2 d for ticks fed on different host species. Premolt period of male nymphs (mean: 15.4 d) was significantly longer than that of female nymphs (14.7 d). Female nymphs were significantly heavier than male nymphs. The overall sex ratio of the adult ticks emerged from nymphs was 0.9:1 (M:F). Capybaras were the most suitable host for the tick adult stage as significantly more engorged females were recovered from them and these females were significantly heavier than those recovered from dogs or rabbits. The life cycle of A. triste in laboratory could be completed in an average period of 155 d. The potential role of guinea pigs, birds and capybaras, as hosts for A. triste in nature, is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of spring acid episodes on macroinvertebrates revealed by population data and in situ toxicity tests

1. While streams in Europe and North America are now recovering chemically from chronic acidification, severe episodic acidification continues to threaten sensitive biota. To appraise further the biological importance of episodic acidification, we surveyed the distribution of the mayfly Baetis alpinus in streams in the Southern Alps (Canton Ticino, Switzerland) in relation to runoff acidity during spring floods. Moreover, to improve mechanistic understanding, in situ toxicity assays were carried out on nymphal B. alpinus during low flows and spring floods, both in streams prone to acid episodes and in well‐buffered controls. 2. Streams surveyed for invertebrates represented three groups which contrasted in susceptibility to episodic acidity. Group one included streams that were acid (alkalinity <0) in spring; group two streams were susceptible to acid episodes because of low base‐flow alkalinity (<200 μeq L^?1); and group three streams were well‐buffered and unlikely ever to be acid. The abundance of B. alpinus was similar among groups during stable flows in winter and summer, but was significantly lower in groups one and two following spring snowmelt. 3. During the bioassays, control streams remained circumneutral to alkaline (pH >6.4). By contrast, episodic streams were circumneutral at low flows, but became acid (pH 4.5–5.6 and total dissolved aluminium to 276 μg L^?1) during intense spring snowmelt. After 15‐day exposures, nymphal B. alpinus survival in the circumneutral control streams exceeded 92% irrespective of flow. In the episodic streams, survival matched the controls during low flows, but declined significantly to 10–20% during acid episodes in spring. Shorter exposure (2–4 days) to pH 5.5–5.7 did not cause significant mortality either during the exposure or over the following 7 days, indicating that B. alpinus might recover from short acid episodes. 4. Our data suggest that the spring distribution of B. alpinus in acid sensitive parts of the Alps directly reflects the toxicity of acid runoff during snowmelt. Our study illustrates that even mild episodic acidification can have significant consequences in Alpine streams for one of the most important invertebrate indicators of acidity.     

Description of Optioservus gapyeongensis new species and Heterlimnius hasegawai (Nomura) (Coleoptera: Elmidae) new to Korea

A new riffle beetle species Optioservus gapyeongensis n. sp. is described from the adult and larval stages. Heterlimnius hasegawai (Nomura), previously misidentified in Korea as Optioservus (Cyclolimnius) kubotai Nomura or Optioservus variabilis Nomura, is redescribed. The adults and larvae of both species inhabit attached mosses on substrates of clean mountain streams, headwaters or springs. Photographs of dorsal adults and habitats and line drawings of diagnostic characters are provided.     

Population dynamics and resource utilization by larval Chironomidae (Diptera) in a backwater area of the River Danube

1. The five most abundant species of the larval chironomid community in a backwater area of the River Danube were analysed in terms of population dynamics and utilization of space from July 1985 to July 1986. The life histories of Prodiamcsa olivacea (Meigen), Cryptochironomus defectus (Kieffer), Harnischia curtilamellata (Malloch), Polypedilum laetum (Meigen) and Polypedilum scalaenum Schrank were described; the number of estimated generations per year was two for P. olivacea, H. curtilamellata, P. laetum and P. scalaenum and three for C. defectus. A decline in larval densities of P. olivacea and P. scalaenum was significantly correlated with increasing cumulative water discharge in an area close to a dam (P<0.01). 2. Spatial overlap and resource width were estimated for these chironomid species across four ranges of water depth, in three sections of the River Danube. An increasing mean spatial overlap between larval species coincided significantly with higher mean resource utilization in all cross-sections during the sampling period. Simulations of spatial overlap between randomized species associations were conducted for analyses of coexistence and dispersion between larval populations. On the basis of comparison with a neutral model, in which patches of individuals were randomly reassigned to habitat units, spatial segregation was significantly (P<0.05) different from chance for seventy-three out of 263 species pairs examined through the year. 3. An analysis of the spatial dispersion of each chironomid species (using the standardized Morisita index) suggested temporally and spatially varying patterns of dispersion, whereas the mean spatial segregation between patches of larval species might have resulted from temporary formations of random patches in this backwater area of the River Danube. 4. Spatial stability estimated as the minimum positive eigenvalue of the species matrix was significantly positively related to mean spatial segregation, indicating that a lower habitat segregation between patches of larval species pairs may lead to a destabilization of the larval species assemblage.     

Life history and secondary production of Glossosoma nigrior Banks (Trichoptera: Glossosomatidae) in two Alabama streams with different geology

We studied life history and secondary production of a caddisfly scraper, Glossosoma nigrior, in two Alabama streams. Collier Creek, located within the Appalachian Plateau physiographic province, is underlain by sandstone bedrock, while Hendrick Mill Branch is located in the Valley and Ridge physiographic province with limestone bedrock. G. nigrior populations in both streams exhibited trivoltine life histories, which were attributed to the higher water temperature regimes than those found in more northern streams. Mean larval density (556 m⁻²) and biomass (B) (49.2 mg AFDM m⁻²) were much higher in Hendrick Mill Branch than Collier Creek (78 m⁻² and 6.7 mg AFDM m⁻²). G. nigrior in Hendrick Mill Branch maintained continuous larval growth and higher larval density than Collier Creek throughout the year mainly due to a greater availability of optimal habitat, a more stable hydrology, and warmer winter water temperature. These factors also resulted in the much higher annual secondary production (P) in Hendrick Mill Branch (965 mg AFDM m⁻²; P/B = 18.3) than Collier Creek (115 mg AFDM m⁻²; P/B = 17.9). Gut content analysis revealed that algae (>50%) and detritus (>40%) were the major diet items for G. nigrior, and the majority of secondary production (>80%) was contributed by the consumption of algae. Glossosoma populations play an important role in trophic linkage in these streams with their high production and grazing activities. Handling editor: D. Dudgeon     

Occurrence of Appias albina albina (Boisduval, 1836) (Lepidoptera: Pieridae: Pierinae) in northern Australia: phenotypic variation,life history and biology,with remarks on its taxonomic status

Variation in adult phenotype, the life history and general biology of the “White Albatross”, Appias albina albina (Boisduval, 1836), are described and illustrated from the monsoon tropics of the northern Australia for the first time. Like elsewhere throughout the species' wide geographical range, the population exhibits sex‐limited polymorphism, with females having three distinct color morphs (white, yellow, intermediate). Variation within and among these morphs is compared with populations from elsewhere in South‐East Asia, particularly Maluku (including the type locality Ambon), and comments are made on the taxonomic status of the Australian population. The species inhabits coastal semi‐deciduous monsoon vine‐thicket where its larval food plant Drypetes deplanchei (Brongn. & Gris) Merr. (Euphorbiaceae) grows on lateritic edges and cliffs. The early stages and behaviour are compared with those of A. albina pancheia Fruhstorfer, 1910 from South‐East Asia and A. paulina ega (Boisduval, 1836) from Australia. Adults are highly seasonal, their timing of appearance coinciding with annual leaf flush of the larval food plant and onset of the summer monsoon. During this period, the broad flight season lasts about two months, the life cycle is completed in approximately four weeks, and the species is probably univoltine or partially bivoltine. We conclude that breeding populations of A. albina albina in Australia are resident, but it remains to be established how the species survives the long dry season.     

Intraspecific developmental variation in the life cycle of the Andean Treefrog (Boana riojana): A temporal analysis

Intraspecific variation during the anuran larval period has been analyzed mainly in relation to the timing of metamorphosis and body size at metamorphosis. However, other traits may vary as well. We examined two developmental series of Boana riojana from the same population in two consecutive years and describe intraspecific variation in larvae of this species. We discuss how variation, if present, may influence its life cycle. We found that both larval series differed in the larval period length, one twice as long as the other. This variation primarily depended on when breeding occurred, metamorphosis was achieved during late spring in both generations and at similar sizes, and only the rate of larval development during premetamorphosis varied extensively between years. This is consistent with thyroid gland activity because when it became active the developmental trajectory became more canalized. No variation of staging sequence occurred in relation to the different durations of the larval period. However, in the long-lasting series we found two different morphs. Also, integument, thyroid gland, skeleton, and testis differentiation events occurred at the same developing stages. In contrast, ovarian differentiation proceeded at the same absolute age in both series. Sexual dimorphism becomes evident within the year after metamorphosis. The intraspecific heterochrony that we describe for the larval development of B. riojana does not lead to phenotypic variation at the end of metamorphosis. We discuss the importance of analyzing growth and development independently. Each proceeds differently in time, but with an interdependence at some point, because size and shape do not vary at the end of metamorphosis.