Flow regime shapes seasonal patterns of fish species richness and abundance in main and branch channels of a rice irrigation system

Current modernization of an irrigation system degrades fish habitats in quantity and quality and is a significant concern for biodiversity conservation and management of ecosystem services in rice farming landscapes. Irrigation systems consist of various types of channels, whose hydrological and hydraulic heterogeneities can contribute to the coexistence of diverse fish species in this flooded habitat. We compared seasonal patterns of fish species richness and abundance between main and branch channels which have different functions in an irrigation system with different flow temporality and magnitude: the main channels (mean width 425 cm and mean discharge 0.467 m³/s in irrigation period) and the branch channels (176 cm and 0.115 m³/s, respectively). The branch channels are small and temporary, but densities of fish species richness and abundance were not smaller than the main channels during the irrigation period. Further, clear positive hysteretic loops in species richness and abundance with discharge were found in the branch channels, which indicates that fish species richness and abundance gradually increased with discharge during this hydroperiod. Water velocity strongly constrained species richness and abundance in the main channels but not in the branch channels partially because of slow-flow patches at microhabitat scale with a larger vegetation coverage. We also found that the main channels provided deeper habitats in the non-irrigation period and contributed to maintain fish species richness and abundance. Therefore, managing both the main and branch channels as an indispensable, interconnected channel network can be a key for fish habitat conservation in an irrigation system.     

Changes in isoenzymes and amino acids in forage and germination of the first post-flight generation of seeds of three legume species after space flight

Seeds of sainfoin ( Onobrychis viciifolia Scop.), alfalfa ( Medicago sativa L.) and Astragalus adsurgens Pall. were put into and recovered from earth orbit from China in 1994. The isoenzymes in leaves and flowers and amino acids in leaves of the first post-flight generation of plants were analysed. Germination of their seeds under NaCl and polyethylene glycol (PEG) stress were tested. The results showed that space flight caused some changes in the pattern of peroxidase and esterase in sainfoin and A. adsurgens , and variation in amylase patterns in leaves of alfalfa. The total amino acid content increased in sainfoin and alfalfa leaves. Under salt and water stress, the proportion of progeny seeds of alfalfa and A. adsurgens , respectively, germinating after 7 and 18 days' imbibition was not markedly different between treatment and control. However, the progeny seeds of sainfoin which had been in orbit exhibited higher tolerance to NaCl and PEG stress during germination.     

从邵大亨的“鱼化龙”壶看“鱼”的向善之美

邵大亨的紫砂壶作品"鱼化龙"壶兼具造型美、趣味性和文化内涵,形象表现了传统文化中的"鱼化龙"思想。本文从"鱼化龙"壶的造型和"鱼"的文化背景,结合邵大亨的生平,简要分析了"鱼化龙"的造型之美、文化内涵和审美价值,证明"鱼化龙"壶具有向善之美。     

Seasonality and synchrony of reproduction in three species of nectarivorous Philippines bats

Background  

Differences among species and among years in reproductive seasonality (the tendency for clusters of events to fall at approximately the same point in each year) and synchrony (amount of clustering of events within a year) have been intensively studied in bats, but are difficult to assess. Here, we use randomization methods with circular statistics to test for synchrony and seasonality of reproduction in three species of nectarivorous megachiropteran bats on Negros Island in the central Philippines.     

Performance of three thermally treated tropical wood species commonly used in Turkey

Thermally modified wood is being increasingly offered in Europe as an alternative to preservative-treated timber. The aim of this study is to determine the change of various physical properties (oven-dry density, air-dry density, weight loss, swelling and anti-swelling efficiency (ASE)), compression strength parallel to grain, colour difference (ΔE), glossiness and surface roughness of sapele (Entandrophragma cylindricum), limba (Terminalia superba) and iroko (Chlorophora excelsa) woods after heat treatment under different temperatures and durations. For this study wood specimens were subjected to heat treatment under atmospheric pressure and air at two different temperatures (160 °C and 180 °C) and two different times (2 h and 4 h). Multiple physical properties (oven-dry density, air-dry density, and swelling), compression strength parallel to the grain and surface roughness of the heat-treated wood and control samples were tested. A stylus method was employed to evaluate the surface characteristics of the samples. Roughness measurements using the stylus method were made in the direction perpendicular to the fiber. Four main roughness parameters which are mean arithmetic deviation of profile (Ra), mean peak-tovalley height (Rz), root mean square roughness (Rq), and maximum roughness (Ry) obtained from the surface of wood were used to evaluate the effect of heat treatment on the surface characteristics of the specimens. Significant difference was found (P = 0.05) between physical and technological properties, and surface roughness parameters (Ra, Rz, Ry, Rq) at two temperatures and two durations of heat treatment. Based on the findings of this study, the results showed that oven-dry density, air-dry density, swelling, compression strength parallel to grain and surface roughness values decreased with increasing treatment temperature and treatment time. Thus, sapele, iroko, and limba wood can be utilized with proper heat treatment techniques for outdoor and indoor applications.     

The shoot-feeding ecology of three Tomicus species in Yunnan Province,southwestern China

Three Tomicus pine shoot beetles, T. yunnanensis (Kirkendall and Faccoli) (Coleoptera: Scolytidae), T. minor (Hartig), and T. brevipilosus (Wood and Bright), have been causing serious damage to Yunnan pine ( Pinus yunnanensis (Franchet) (Pinales: Pinaceae)) stands in Yunnan, southwestern China. However, their ability to coexist in the crowns of the same trees during the shoot-feeding phase has not been elucidated. In our study, we investigated and compared the shoot-feeding ecology of the three species of pine shoot beetle in P. yunnanensis in Anning County, Yunnan Province. Shoot-feeding by T. yunnanensis, T. minor, and T. brevipilosus initiated in April, May, and June, and ended in February, April, and May, respectively. Individual T. yunnanensis and T. minor adults fed in shoots for about seven months, and T. brevipilosus for nine months, before initiating reproduction. All three Tomicus species fed in the current-year shoots close to the apical bud. No specific overwintering behavior was observed prior to reproduction. The entrance hole of T. yunnanensis was furthest away from the apical bud, and T. minor was the closest to the apical bud. Differences in the spatial distribution of these shoot-feeding sites might reduce competition among the three beetle species. The long-lasting and overlapping shoot-feeding by the three Tomicus species may reduce the resistance of P. yunnanensis and facilitate the reproduction of these beetles in the trunks of living trees, and thus help explain the severe damage by Tomicus in P. yunnanensis.     

Genetic patterns of ten Elymus species from the Tibetan and Inner Mongolian plateaus of China

Genetic diversity was investigated for forty populations of ten Elymus species from the Tibetan and Inner Mongolian plateaus of China using allozyme and micro‐satellite markers. The two assays differed in the amount of polymorphism detected. Micro‐satellites detected the higher amounts of polymorphism. For allozymes and micro‐satellite markers, between populations of each species, the proportion of polymorphic loci, heterozygosity and Shannon's Information index ranged from 0·1667 to 0·833, and 0·455 to 1·00, respectively, 0·0800 to 0·2528 and 0·1622 to 0·3619, respectively, and 0·1173 to 0·3769 and 0·2248 to 0·5318 respectively. As for gene flow at the species and population levels, limited gene flow was found between populations within species and between species. From a geographical standpoint, samples from different regions showed a range of values. Populations from the Tibetan Plateau of China had higher genetic variation than from the Inner Mongolian plateau both using allozyme and micro‐satellite markers.     

Effects of temperature and light on the hatching of overwintering eggs in three Japanese Sympetrum species

The aim of the present study was to obtain quantitative information on egg hatching with respect to temperature and light to clarify the effect of cultivation methods on three Japanese Sympetrum species. Eggs of three Sympetrum species were collected on October 2005 at Akita prefecture located at north of Japan, and the eggs had been laid on soil surface of paddy field till April 2006. The eggs (3 trays with 50 eggs each) were held under four constant temperatures (8, 13, 18 and 23°C) with a photoperiod (L:D 14:10; relative light intensity 3,000 Lux) and 23°C in darkness. No S. infuscatum eggs, but 67 and 60% S. frequens and S. darwinianum hatched in constant darkness. This result suggests that S.frequens and S.darwinianum do not require light for hatching, but S.infuscatum requires light for hatching. Eggs of S. darwinianum and S. infuscatum did not hatch at 8°C. In S. frequens, some eggs hatched but the hatching rate was significantly lower at 8°C than at higher temperatures (P < 0.05). At higher temperatures, the hatching rate did not differ significantly for three Sympetrum species. At 13°C, S. infuscatum hatched fastest, 0.18 for S. infuscatum, 0.11 for S. darwinianum and 0.08 for S. frequens. The mean head width of second stadium larva of S. frequens, S. darwinianum and S. infuscatum were 0.4 ± 0.01, 0.4 ± 0.01 and 0.6 ± 0.01 mm (SD), respectively. These results suggest that S. infuscatum may have a competitive advantage over S. frequens and S. darwinianum under conditions that favor S. infuscatum through hatching speed.     

Allelopathic potential of Lolium rigidum Gaud. on the early growth of three associated pasture species

In Mediterranean areas, the establishment of multi‐species pastures for extensive livestock use is an alternative to the growing of traditional cereal crops. Lolium rigidum Gaud. is one of the most valuable forage grasses adapted to semiarid environments but its performance in mixtures is not fully understood. Field observations suggest that the species exerts allelopathic effects, although there is no evidence in the literature to support this assumption. The objective of the study was to determine whether L. rigidum affects the germination and seedling growth of common forage species by allelopathic means. Two bioassays were conducted to test for the allelopathic potential of seeds and adult (shoot and root) tissues of L. rigidum on two grasses, Lolium multiflorum Lam. and Dactylis glomerata L., and a legume, Medicago sativa L. The three species showed different degrees of sensitivity to L. rigidum with L. multiflorum being particularly sensitive to allelopathy. Positive and negative effects of L. rigidum on seedling development were noted. Shoot extracts of L. rigidum displayed the most consistent negative effects by inhibiting elongation of the radicle of the three target species. The significance of the results is that in drought‐prone environments and where water resources are scarce poor root development decreases the ability of the plants to grow and survive.     

Comparing the levels of trace metal from two fish species harvested from treated waste water in Pretoria, South Africa

The persistent problem of water scarcity with the ever increasing demand of water has necessitated the reuse of effluent in agriculture. The present study evaluated the reuse of treated waste water and bioaccumulation properties of two fish species from a manmade lake. Trace metals content of two fish species: Clarias gariepinus and Cyprinus carpio and levels of trace metals from waste water in the lake where the fish species were harvested were determined by Inductive Couple Plasma-Optical Emission Spectrometer (ICP-OES). The trace metal values from fish samples ranged between 0.45-4.41 microg g(-1) for Cu, 16.45-72.23 microg g(-1) for Zn, 1.92-4.71 microg g(-1) for Cr, 2.45-5.65 microg g(-1) for Ni, 10.23-44.31 microg g(-1) for Mn, 9.67-46.59 microg g(-1) for Fe and 0.12-0.56 microg g(-1) for Pb. The carp exhibited a significantly higher concentration for the trace metals for all the parts analyzed (p<0.01). The levels of trace metals concentration from Cyprinus carpio was in the order liver>gill>muscle>bone and metal accumulation was in the order Zn>Fe>Mn>Cr>Ni >Cu>Pb. The concentration of trace metals such as zinc, iron, chromium and nickel were higher than the recommended legal limits for human consumption. The result revealed that properly treated waste water could be used for the purpose of aquaculture. Clarias gariepinus bio accumulated more trace metals from the lake when compared with Cyprinus carpio.     

Interactions of slope and canopy of herbage of three herbage species on transport of faecal indicator bacteria by rain splash

The movement of faecal pathogens from land to surface and ground‐water are of great interest because of the public and livestock health implications. Knowledge of canopy structure and how it might be managed to help mitigate nutrient and pathogen movement in pasture is needed to create management practices that balance livestock production with environmental benefits. An experiment was conducted using a rainfall‐simulating device to test whether canopy structure of species common to pastures in Appalachia, USA could be managed to influence dispersion of faecal pathogens. Seven pots (30‐cm diameter) of white clover, orchardgrass and perennial ryegrass were lined up on horizontal and sloping surfaces under a rainfall simulator. The centre pot was inoculated at the soil surface with 4 × 10¹⁰ faecal coliform bacteria (FC) just before rainfall simulation started. The species were maintained under short, moderate and tall canopy management treatments. White clover exhibited the greatest rates of lateral and vertical dispersion of FC into the canopy, especially in the short canopy management treatment following 30 min of rainfall (about 40 mm). Low concentrations of faecal coliform bacteria also dispersed into the canopies of the grass species but the differences in concentration of FC between the grass species were not different. When the proportion of white clover in a pasture is high, the canopy should be relatively taller to reduce the likelihood of infection associated with faecal coliform‐contaminated herbage.     

Inheritance patterns of reducing sugars in potato tubers after storage at 12 C and 4 C followed by reconditioning

Progenies from crosses of ND860-2, a low reducing sugar clone, with two potato cultivars (Trent and Onaway), differing in reducing sugar content, as well as the progenies of the parents selfed, were examined for reducing sugar content. Tubers were assessed after storage at 12 C for 10 weeks (regular storage) and 4 C for 10 weeks followed by reconditioning at 20 C for two weeks (reconditioning). After regular storage, all seedling progenies had relatively high frequencies of low reducing sugar segregates (i.e., equal or less than those of ND860-2 clone). After reconditioning, a high frequency of seedlings with low reducing sugars was observed in the progeny from ND860-2/Trent (46.7%), however, they were also found in the progeny from ND860-2/Onaway (6.7%). Results of this study suggested that progenies from crosses involving ND860-2 would segregate for low reducing sugar content regardless the reducing sugar level of the other parent.     

Extracellular production of silver nanoparticles by using three common species of dermatophytes: Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis

Background: To develop a new green approach for biosynthesis of silver nanoparticles, myconanotechnology has been represented as a novel field of study in nanotechnology. In this study, we have reported the extracellular synthesis of highly stable silver nanoparticles using three species of dermatophytes: Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis. Methods: Clinical strains of these species were grown in a liquid medium containing mineral salt and incubated at 25°C for 5-7 days. The cell-free filtrate of each culture was obtained and subjected to synthesize silver nanoparticles in the presence of 1 mM AgNO₃. Results: The reduction of Ag+ ions in metal nanoparticles was investigated virtually by tracing the solution color which was switched into reddish-light brown after 72 h. For T. mentagrophytes, a UV-visible spectra demonstrating a strong, quite narrow peak located between 422 and 425 nm was obtained. For M. canis, a fairly wide peak centering at 441 nm and for T. rubrum, a weak spectrum to decipher were observed. According to transmission electron microscopy (TEM) results, fairly uniform, spherical, and small in size with almost less than 50 nm particles were forms in case of T. mentagrophytes. For the other two species, TEM images showed existence of small spherical nanosilvers but not as small as nanoparticles synthesized by T. mentagrophytes. Conclusion: We observed that species belong to a single genus of the fungi have variable ability to synthesize silver nanoparticles extracellulary with different efficiency. Furthermore, the extracellular synthesis may make the process simpler and easier for following processes.Key Words: Nanoparticles, Dermatophytes, Extracellular biosynthesis     

Ecological conservation and the restoration of freshwater environments in Korea

In this study, we aim to construct and apply a simple genetic algorithm (SGA) to optimize a large number of parameters of an one-box ecosystem model. The ecosystem model was used to simulate the water quality over a 6-month period based on the new observation data in an agricultural pond which was strongly influenced by a green algal bloom. Of the 54 parameters in this model, 10 important parameters were initially selected for the optimization, with one other parameter being subsequently added. The SGA program was used for three purposes, namely (1) to narrow the search space for the 10 parameters, (2) to assess the influence of the additional parameter on the optimization results, and (3) to observe the distribution and convergence of the optimized values for the 10 selected parameters. In the next step, new ranges for these 10 important parameters were assigned and the SGA was applied to all 54 model parameters to seek the optimum value for each parameter. The modeling approach and the results presented here provide valuable and reliable evidences of the optimum parameters for further simulations to clarify the mechanisms of the biochemical processes in the water.     

Toxicity of quinones against two-spotted spider mite and three species of aphids in laboratory and greenhouse conditions

Toxicities of the eight quinones were evaluated through leaf dip bioassays conducted against Tetranychus urticae, Myzus persicae, Myzocallis walshii, and Illinoia liriodendri. Based on LC₅₀ values, plumbagin (LC₅₀ = 0.001%) was the most active compound against T. urticae and ubiquinone Q₀ (LC₅₀ = 0.005%), plumbagin (LC₅₀ = 0.010%), and dibromothymoquinone (LC₅₀ = 0.012%) were the most active compounds against M. persicae. The most active compounds against M. walshii were juglone (LC₅₀ = 0.011%) and ubiquinone Q₀ (LC₅₀ = 0.019%), whereas dibromothymoquinone (LC₅₀ = 0.030%), plumbagin (LC₅₀ = 0.033%) and ubiquinone Q₀ (LC₅₀ = 0.058%) were the most toxic to I. liriodendri. Ecotrol (positive control) was the least toxic compound (LC₅₀ = 0.39%) against T. urticae and M. persicae (LC₅₀ = 0.447%). Although the majority of the compounds tested were toxic to all four test species in residual bioassays, there was little overlap among the test species in terms of susceptibility to the compounds and interspecific differences were observed. Regarding structure-activity relationships for quinones, the addition of a hydroxyl group resulted in a significant increase in the toxicity of the 1,4-naphthoquinones, and those possessing a methyl group exhibited the highest levels of activity in T. urticae. The bromine atom at the 2- and 5-positions of the benzoquinone ring is crucial to the toxicity of the compounds against I. liriodendri. Toxicity was greatly affected not only by the number of hydroxyl groups, but also by their positions in the ring in the case of M. walshii. Juglone and plumbagin as residual toxins in the laboratory also reduced the population of two-spotted spider mites compared to EcoTrol™ (positive control) and the negative control in the greenhouse experiment. Some quinones tested may have potential as commercial insecticides and miticides, or alternatively, could serve as lead compounds for the development of more potent crop protection agents.     

Insecticidal efficacy of two pirimiphos-methyl formulations for the control of three stored-product beetle species: Effect of commodity

Laboratory bioassays were conducted to evaluate the insecticidal effect of two pirimiphos-methyl formulations, an emulsifiable concentrate (EC) and a capsule suspension (CS) against adults of Sitophilus oryzae, Rhyzopertha dominica and Tribolium confusum in wheat, maize and rice. Pirimiphos-methyl was applied at two dose rates, 2 and 4 ppm, and adult mortality was measured after 2, 7, 14 and 21 days of exposure in the treated commodity. Progeny production was assessed 65 d after the removal of the parental adults. S. oryzae adult survival was significantly higher in rice than in wheat and maize, whereas T. confusum mortality was significantly higher in maize than in the other grains. From the species tested, the most susceptible species was S. oryzae, for which mortality reached 100% after 7 days of exposure in treated wheat and maize, followed by T. confusum and R. dominica. Progeny production was significantly suppressed by pirimiphos-methyl in the case of S. oryzae, but not in the case of R. dominica. In general, only few differences in performance between the EC and the CS formulation were detected. We conclude that the type of grain commodity significantly affects mortality after the application of the two pirimiphos-methyl formulations tested, but this effect is species-dependent.     

Silage fermentation characteristics of three common grassland species in response to advancing stage of maturity and additive application

This study investigated the effects of advancing stage of maturity and additive treatment on the fermentation characteristics of three common grassland species. Perennial ryegrass (PRG; Lolium perenne L., var. Gandalf), timothy (Phleum pratense L., var. Erecta) and red clover (Trifolium pratense L., var. Merviot) were harvested at three dates in the primary growth (11 May, 8 June and 6 July; Harvests 1–3) and ensiled with the following additive treatments: (1) control (i.e. no treatment), (2) formic acid‐based additive, (3) homofermentative lactic acid bacterial (LAB) inoculant and (4) heterofermentative LAB inoculant. Additive application to the PRG (irrespective of harvest date), the late‐harvest timothy (Harvest 3) and the red clover (Harvests 2 and 3) herbages had little impact on silage fermentation characteristics, where a lactic acid dominant fermentation already prevailed. However, the application of the formic acid‐based additive to the Harvest 1 and 2 timothy and Harvest 1 red clover herbages, where the silage fermentation characteristics were poorer, resulted in an increase in the proportion of lactic acid in total fermentation products and a decrease in pH. In contrast, the heterofermentative LAB inoculant had a negative impact on silage fermentation characteristics where a poor preservation prevailed in the corresponding control silage.     

Changes in species composition of abandoned sown swards after imposing seasonal cutting treatments

Abstract Seasonal cutting treatments were imposed on abandoned perennial ryegrass/white clover swards at three sites in the UK to determine the impact on species diversity and the contribution of different species to biomass. Before the cutting experiment, the abandoned swards had received no fertilizer applications and had been neither grazed nor cut for 3 years. The original sown species, Lolium perenne and Trifolium repens, had virtually disappeared during this period. Self‐sown grasses, including Agrostis capillaris, Dactylis glomerata, Festuca rubra, Holcus mollis, Poa pratensis and P. trivialis, had become dominant at two sites. Ranunculus repens was the dominant species at the third site, and self‐sown grasses, such as Holcus lanatus and P. trivialis, and Juncus and Carex species were also present. The standing herbage in 2·5 m × 2·5 m subplots was cut to 2·5 cm above ground level and removed annually in either June or October for 7 years at two sites and 6 years at the third site. Total biomass removed was generally < 4 t dry matter (DM) ha^?1, and both total and live biomass decreased over time in the June cutting treatment at two sites. There were large changes in species composition after initiating the two cutting treatments. The numbers of grass and dicot species increased, although many new species had a low frequency of occurrence. The contribution of species to biomass changed over time, with species showing a vegetative regenerative strategy decreasing over time at one site. At this site, annual cutting in June was slightly more effective than cutting in October in reducing the dominance of R. repens; cutting in early October effectively reduced Juncus spp. At two sites, there was a decrease in the contribution of the species group showing seasonal regeneration by seed, and differences between cutting dates for two species within this group at one site. L. perenne and T. repens remained at much lower levels than in adjacent unfertilized, grazed swards. Reseeding may be necessary to create species assemblages for ecological and agricultural objectives.     

Comparative overwintering host range of three Adelphocoris species (Hemiptera: Miridae) in northern China

In northern China, Adelphocoris suturalis, Adelphocoris lineolatus and Adelphocoris fasciaticollis (Hemiptera: Miridae) are common pests of cotton and several other crops. These species have vastly diverse geographic distribution, seasonal dynamics and abundance, the underlying causal factors of which are poorly understood. In this study, the importance of a broad range of plant species as overwintering hosts for each Adelphocoris sp. was compared. Nymphal emergence from a total of 126 plant species was monitored at two distinct locations. The eggs of A. suturalis successfully eclosed from un-plowed cotton field soil and 115 plant species, primarily pastures, weeds and agricultural crops. The eggs of A. lineolatus successfully eclosed from 40 plant species, mainly pastures and weeds. Finally, A. fasciaticollis overwintered on 35 plant species, primarily tree species, weeds and agricultural crops. In conclusion, the most common and widely distributed mirid species, A. suturalis, overwintered on a comparatively broader range of plants compared to the other two species. These observations help to understand the differences in geographical distribution and abundance of the three Adelphocoris species, and constitute the basis for forecasting and pest management protocols for Adelphocoris spp. in China.