Trophic coupling of the microbial and the classical food web in Lake Baikal,Siberia

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Host-Parasite Interactions from the Inside: Plant Reproductive Ontogeny Drives Specialization in Parasitic Insects

Host plant interactions are likely key drivers of evolutionary processes involved in the diversification of phytophagous insects. Granivory has received substantial attention for its crucial role in shaping the interaction between plants and their seed parasites, but fine-scale mechanisms explaining the role of host plant reproductive biology on specialization of seed parasites remain poorly described. In a comparative approach using plant histological techniques, we tested the hypotheses that different seed parasite species synchronize their life cycles to specific stages in seed development, and that the stage they target depends on major differences in seed development programs. In a pinaceous system, seed storage products are initiated before ovule fertilization and the wasps target the ovule’s nucellus during megagametogenesis, a stage at which larvae may benefit from the by-products derived from both secreting cells and dying nucellar cells. In a cupressaceous system, oviposition activity peaks later, during embryogenesis, and the wasps target the ovule’s megagametophyte where larvae may benefit from cell disintegration during embryogenesis. Our cytohistological approach shows for the first time how, despite divergent oviposition targets, different parasite species share a common strategy that consists of first competing for nutrients with developing plant structures, and then consuming these developed structures to complete their development. Our results support the prediction that seed developmental program is an axis for specialization in seed parasites, and that it could be an important parameter in models of their ecological and taxonomic divergence. This study provides the basis for further investigating the possibility of the link between plant ontogeny and pre-dispersal seed parasitism.     

Chaetognatha of the Namibian Upwelling Region: Taxonomy,Distribution and Trophic Position

In October 2010, the vertical distribution, biodiversity and maturity stages of Chaetognatha species were investigated at four stations located off Walvis Bay, Namibia. Seventeen species were detected and classified as pelagic, shallow-mesopelagic, deep-mesopelagic and bathypelagic species based upon the weighted mean depth derived from their average vertical distribution. High abundances of Chaetognatha were found in the upper 100 m at all stations of the Walvis Bay transect with a maximum value of 20837 ind. 1000 m⁻³ at the outer shelf station near the surface. The community was dominated by species of the Serratodentata group. Furthermore, the distribution of Chaetognatha did not seem to be influenced by low oxygen concentrations. Stable isotope ratios of carbon and nitrogen in Chaetognatha were determined for seven different areas located off northern Namibia. The values of δ¹⁵N ranged from 6.05 ‰ to 11.39 ‰, while the δ¹³C values varied between −23.89 ‰ and −17.03 ‰. The highest values for δ¹⁵N were observed at the Walvis Bay shelf break station. The lowest δ¹³C values were found at the Rocky Point offshore station, which was statistically different from all other areas. Stable isotopes of carbon and nitrogen were determined for four taxa (Sagitta minima, Planctonis group, Sagitta enflata, Sagitta decipiens). In this case, the δ¹⁵N values ranged from 6.17 ‰ to 10.38 ‰, whereas the δ¹³C values varied from −22.70 ‰ to −21.56 ‰. The lowest δ¹⁵N values were found for S. minima. The C- and N-content revealed maximum C-values for S. decipiens and maximum N-values for the Planctonis group. The C:N ratio of Chaetognatha ranged between 5.25 and 6.20. Overall, Chaetognatha are a diverse group in the pelagic food web of the Benguela Upwelling System and act as competitors of fish larvae and jelly fish by preying on copepods.     

Recent Advances in Biological Control of Pest Insects by Using Viruses in China

Insect viruses are attractive as biological control agents and could be a feasible alternative to chemical insecticides in the management of insect infestations. This review describes recent advances in the development of wild-type and genetically modified viruses as insecticides. A new strategy of application of insect viruses in China is reviewed. Also, the assessment of biosafety of genetically modified Helicoverpa armigera Nucleopolyhedovirus (HearNPV) is emphasized as a case-study.     

青海省重要医学昆虫区系分布

目的-调查了解青海省重要医学昆虫的种群组成与分布特征.方法-采用人帐诱、灯诱、挥网和动物体表检虫法采集医学昆虫;收集前人研究文献资料.结果-获得青海省医学昆虫237种,隶属14科62属,其中蚊科2属9种,蠓科2属19种,虻科5属23种,蚋科1属6种,白蛉科2属3种,蚤类6科37属143种,硬蜱科4属7种,恙螨科6属23种和列恙螨科2属4种.从已知医学昆虫237种看,属于青海省北部山地146种,柴达木盆地94种,青南高原96种和分布不详21种.结论-为青海省医学昆虫的区系分布研究提供了依据.     

Distribution of Sunn Pest,Eurygaster integriceps Puton (Hemiptera: Scutelleridae), in overwintering sites

Sunn Pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), is the most serious pest of wheat in West and Central Asia. Following harvest, the pest migrates from wheat fields to high elevations to escape high summer temperatures and, the following spring, moves back to the fields. In this work, Sunn Pest populations were monitored in 21 overwintering sites located in seven provinces (with 800–2500 m elevation) in Iran. Litter samples were taken twice in each site, once in July–November 2002 and again in March 2003. At each site 60 Artemesia sp. bushes were selected at random and litter from each bush was collected and the number of live male and female adult Sunn Pest counted. More Sunn Pests were collected in higher elevations in the first sampling. Golestan (893 m), Kermanshah (1583 m), and Qazvin (1675 m), located in valleys and surrounded by mountainous areas, had < 5 adults/bush. However Azarbayejan (1750 m), Markazi (1883 m), Kordestan (2067 m), and Esfahan (2141 m), located in mountainous areas and/or close to mountains, had 10–52 adults/bush. No noticeable changes in Sunn Pest populations were observed in 17 overwintering sites among 21 between the two sampling times. These results suggest that, after Sunn Pest moves to more highly elevated sites at aestivation time, most of them remain in these sites during overwintering before migration to wheat fields in the spring. Sunn Pest can be targeted for management in these areas during the fall and/or early spring as their movement is clearly limited.     

Bacterioplankton Community Composition in Five Lakes Differing in Trophic Status and Humic Content

Abstract To investigate the relation between lake type and bacterioplankton community composition, five Swedish lakes, which differed from each other in nutrient content and water color, were studied. Denaturing gradient gel electrophoresis (DGGE) of 16S rDNA was used to examine community composition. The DGGE-patterns of the different samples were analyzed in relation to physical, chemical, and biological data from the lakes by canonical correspondence analysis (CCA). The three variables found to most strongly correlate with the DGGE patterns were biomasses of microzooplankton, cryptophytes, and chrysophytes, suggesting that these biota had an impact on bacterioplankton community structure. Two of the three factors were, in turn, significantly correlated to parameters associated with the trophic status of the lakes, indicating that the nutrient content of the lakes, at least indirectly, influenced the structure of the bacterioplankton community. The relation to water color was less pronounced. Received: 16 February 2000; Accepted: 27 April 2000; Online Publication: 18 July 2000     

Protozoan Colonization Rates and Trophic Status of Some Freshwater Wetland Lakes

Primary productivity, chlorophyll a, phosphorus and nitrogen nutrients, and other chemical and physical parameters were measured in 13 wetland lakes in northern lower Michigan. These lakes included several examples located in each of the four major wetland types—bogs, fens, marshes, and swamps. Of the four types, the brown-colored waters of the acid bog lakes generally had the highest levels of primary productivity, chlorophyll a, phosphorus, and nitrogen. Primary productivity correlated positively with water color, total-N, and NH₃-N (α≤ 0.05). By these measures, waters of the bogs were the most eutrophic of the four types of wetland lakes. These findings would seem to contradict the generally-held concept that “dystrophic” bog lakes are extremely oligotrophic. Protozoan colonization of artificial substrate islands was monitored at each wetland site. The correlation between protozoan colonization rates (G values in the MacArthur-Wilson noninteractive model) and primary productivity, measured by 24-h light and dark bottle incubations, was significant at the 95% confidence level (r= 0.850, P= 0.001) and with water color at the 90% confidence level (r= 0.599, P= 0.084). It was concluded that protozoan colonization rate was an excellent indicator of the trophic status of wetland lakes.     

Composition of Heterotrophic Flagellates in Coastal Waters of Different Trophic Status

Heterotrophic flagellates (HFs) are important members of the aquatic microbial food web. However, information on their spatial patterns in relation to eutrophication is limited. Here, we examined the composition and spatial distributions of HFs (<3 μm) in subtropical coastal waters of different trophic status by re-analyzing two previously published small subunit rDNA pyrosequence datasets using information from the newly launched Protist Ribosomal Reference database (PR²). Whereas the contributions of different major clades composing the Marine Stramenopiles (MASTs), picobiliphytes and Chrysophyceae were found relatively comparable between the stations, contrasting compositions of the Marine Alveolates (MALV) groups I and II were observed. The high and relatively stable contribution of MAST-1, -3 and -7 among the MASTs in both stations suggest their importance as bacterial grazers in coastal waters, irrespective of trophic status. By contrast, the dominance of clades 3, 5 and 14 of MALV II in the eutrophic station implies their importance in regulating the dinoflagellate population at the site. Our study provides insights into the ecological importance of different HF groups in eutrophic coastal ecosystems.     

Insects, oxygen, and iron

Konrad Bloch developed an interest in insects because they are unable to make sterols, and in yeast because these cells need oxygen to make sterols and unsaturated fatty acids. Insects, like all other organisms, must deal with the toxic effects of oxygen in the presence of iron, which itself is a vital nutrient. They do so by making proteins with high affinity for ferric or ferrous ions. Two such proteins are transferrins and ferritins. Insects produce both of these proteins, but use them in different ways from most other organisms. Insect transferrins appear to be involved in innate immunity, perhaps by sequestering ferric ions to prevent pathogens and parasites from utilizing them. Insect ferritins, unlike those of any other group of organisms, are exported into the extracellular space (hemolymph). They may be involved in iron transport and/or protection against iron overload in the diet.     

Alternate Stable States and the Shape of the Lake Trophic Distribution

Ecological theory applied to small and shallow lakes suggests that water clarity and primary productivity may be bimodal, reflecting alternate stable states. This hypothesis was tested using remote sensing data. We used estimated Secchi disk transparency derived from reflected light measured by Landsat satellite photosensors. Lake trophic state indices (TSI) were estimated from the transparency estimates. Because alternate stable state theory is typically applied to productive lakes, we predicted that planktonic primary productivity would be especially bimodal in the small and shallow eutrophic lakes of southern Wisconsin. We found that overall, trophic state for over 8000 lakes in Wisconsin was multimodal (at least bimodal). Frequency distributions for lake size categories appeared to be distinctly bimodal. The largest and smallest lakes for all of Wisconsin had significantly bimodal curves, and southern (more productive) lakes had a more distinct multimodal curve than northern lakes. These results support the basic predictions of alternate stable state theory. The significantly trimodal distribution for southern lakes suggests that they may exist in more than just two alternate stable states.     

Distribution of total mercury in peat soil profiles in West Siberia

Total mercury content in peat soils of different botanical composition has been determined. Mercury content in peat depends on principal properties of peat soil such as botanical composition, ash content, degree of peat decomposition, as well as nitrogen, carbon, and humic acid content in peat. A model based on the mercury/biomass concept is proposed to determine the distribution of total mercury in peat soil profiles in West Siberia from the content of the main biogenic elements C and N.     

Net Heterotrophy in Small Danish Lakes: A Widespread Feature Over Gradients in Trophic Status and Land Cover

Nineteen small lakes located in open landscapes or deciduous forests in nutrient-rich calcareous moraines in North Zealand, Denmark, were all net heterotrophic having negative net ecosystem production and predominant CO₂ supersaturation and O₂ undersaturation of lake waters. Forest lakes were poorer in nutrients, phytoplankton, and primary production, but richer in dissolved organic matter and CO₂ than open lakes with more light available. The modeled annual balance between gross primary production and community respiration (GPP/R _COM) averaged 0.60 in forest lakes and 0.76 in open lakes and the ratio increased significantly with phosphorus concentration and phytoplankton biomass but decreased with colored dissolved organic matter. The negative daily rates of ecosystem production resembled estimates of oxygen uptake from the atmosphere to the lakes, whereas estimates of CO₂ emission were 7.2-fold higher. Although CO₂-rich groundwater and anaerobic respiration support greater molar release of CO₂ than uptake of O₂, we suggest CO₂ emission is overestimated. Possible explanations include CO₂ enrichment of the air film above small wind-sheltered lakes. The observed metabolism and gas exchange show that exogenous organic matter is an important supplementary energy source to community respiration in these small lakes and that forest lakes, in addition, experience pronounced light attenuation from trees and dissolved colored organic matter constraining primary production. Kaj Sand-Jensen (KSJ) formulated the original research idea and designed the study. Data analysis (ie. calculations, statistics and figures) was performed by Peter A. Staehr (PAS). The text was for the most part written by KSJ, although with contributions by PAS, especially in describing the applied methods and data analysis.     

河南省公立医院院长职业化现状调查与分析

目的 分析河南省公立医院院长职业化现状和存在的问题,为制定院长职业化培训规划和相关政策提供依据。方法 在2014年河南省公立医院院长培训班上对318名医院院长进行问卷调查,对院长的教育经历、专业情况、管理培训和管理知识来源进行描述性分析。结果 河南省公立医院院长性别比例不协调,学历层次和技术职称级别结构方面相对合理,职业化培训不足,缺少管理类相关知识储备,对公立医院院长职业化的认知参差不齐。结论 应加强公立医院院长的管理类相关知识储备,重视管理队伍的职业化培训,培养具备职业化要求的高层管理人员。