The introduction of the aquatic carnivorous plantAldrovanda vesiculosa to new potential sites in the Czech Republic: A five-year investigation

Five microsites in shallow dystrophic waters were selected for the introduction of a critically endangered aquatic carnivorous plantAldrovanda vesiculosa in the Třeboň region in S Bohemia, the Czech Republic. The selected sites were fen pools close to two hypertrophic fishponds, Ptačí blato (four microsites) and Domanínsky (one microsite). In June 1995, 30 plants from an allochthonous population in E Poland were introduced in each of the microsites. Water chemistry and plant growth dynamics were investigated at the microsites throughout the 1995–1996 seasons, and the maximum size of the subpopulations were estimated during the 1997–1999 seasons. The selected waters may be characterized as oligo-mesotrophic. The warm and dry 1995 season resulted in a low water level (ca. 10 cm below average) and plant propagation was poor at all but one microsite. However, the rainy and colder 1996 season resulted in a high water level, and thus rapid plant propagation occurred at all four microsites at the Ptačí blato fishpond and between 841 and 2669 turions were formed. Here, the doubling time of the apices was between 13.5–19.3 days in the summer. At the Domanínsky fishpond, however, the growth was relatively poor in 1996. The overwintering rate of turions (19–100%) was found as being high enough to keep the introduced plant populations stable. At each of the four microsites at Ptačí blato, the maximum numbers of shoot apices were estimated to be between 1,000–20,000 in the 1997–1999 seasons. Depth of free water appears to be the crucial factor for the rapid growth ofAldrovanda at some selected sites; water depth below 5 cm is unfavourable. Overall,Aldrovanda was successfully established in an intensively agricultural landscape in the Třeboň region.     

Field growth characteristics of two aquatic carnivorous plants,Aldrovanda vesiculosa andUtricularia australis

Basic growth characteristics of two species of free-floating submerged carnivorous plants, the very rare and stenotopicAldrovanda vesiculosa and the very common and eurytopicUtricularia australis, were investigated in a 10/11-day field growth experiment within three nylon enclosures at two artificialAldrovanda sites in the T?eboň region, S Bohemia, Czech Republic, at the peak of a growing season. Growth ofAldrovanda was best at a meso-eutrophic site (biomass doubling time,T ₂, 8.4–10.7 days, mean growth of new leaf whorls 0.96 whorls days^?1, 1.6 developed branches per shoot) and slower at an oligo-mesotrophic site (T ₂ 17.2–21.5 days, growth of whorls 1.01 whorls days^?1, 0.1–0.5 branches per shoot). Growth ofUtricularia was similar at both sites (T ₂ 19.8–33.2 days or 9.1–16.8 days, growth of whorls 3.1 or 2.7 whorls days^?1, 1.5–2.1 or 0.8–1.4 developed branches per shoot at the former or latter site, respectively). Throughout the experiment, both species at the meso-eutrophic site allocated relatively more biomass to the production and growth of branches, than to that of new whorls. The results show thatAldrovanda, although usually considered as competitively weaker, can grow faster during the growing season peak thanUtricularia due to frequent branching and the subsequent rapid growth and separation of daughter shoots. Very rapid growth of rootless aquatic carnivorous plants in nutrient-poor habitats allows the consideration of ecophysiological adaptations that enable the plants to gain limiting mineral nutrients. These adaptations include carnivory, efficient nutrient reutilization from senescent shoots, and very high affinity for mineral nutrient uptake from water. Comparison of growth rates of rare and stenotopicA. vesiculosa and very common and eurytopicU. australis shows that differences in their rarity do not seem to be based on differences of growth rate.     

Cytochemical and ultrastructural aspects of aquatic carnivorous plant turions

Turions, which are modified shoot apices, are vegetative, dormant overwintering organs produced by perennial aquatic plants. In this study, the turion cytochemistry and ultrastructure of Aldrovanda vesiculosa, Utricularia vulgaris and U. stygia were compared with particular emphasis placed on storage substances. These three aquatic, rootless carnivorous plant species were studied at the end of their winter dormancy. At this stage, the turions of all species had starch as their main storage material. In contrast with A. vesiculosa, Utricularia turions were rich in protein storage vacuoles, and proteins were also accumulated as crystalline inclusions in the nuclei. All examined species accumulated lipid droplets in cells of epidermal glands.     

Contrasting the farm-scale spatio-temporal dynamics of boundary and field overwintering predatory beetles in arable crops

In many European countries agri-environment funding can improve ecosystem services, including the adoption of conservation biocontrol, through the creation of habitats that encourage beneficial arthropods. Predatory beetles are amongst the most numerous and diverse arthropods present in arable fields. The primary ecosystem services provided by predatory beetles are in biological control and food chain maintenance as they are a key resource for many higher organisms. However, to be effective biological control agents, able to respond quickly to wherever a pest infestation occurs, then they must be sufficiently abundant and widely distributed. Conservation biocontrol utilising predatory beetles has focussed on the impact of species that overwinter in adjacent field boundaries, although those overwintering within fields are often more abundant. If the abundance and distribution of predatory beetles is to be maximised then further knowledge of their spatial dynamics is required to ensure habitats are arranged appropriately. The spatio-temporal dynamics of boundary and field overwintering species was measured across 64 ha encompassing six fields and for three consecutive years using a grid of 973 pitfall traps. Boundary species were more numerous in spring (May and June) whereas more field species were captured in July. The species composition was comprised of relatively few taxa. Boundary species occurred in small patches that were distributed across the fields in spring, but were only found close to the margins in July. Patches persisted in some locations over two years. Field species occurred in larger patches, spread across particular fields and these were stable within years and to some extent between years. Game-cover strips were attractive to boundary species in the spring and summer and did not effect predator distribution in the adjacent crop. Handling Editor: Eric Lucas.     

Respiration of turions and winter apices in aquatic carnivorous plants

Basic respiration characteristics were measured in turions of six aquatic plant species differing greatly in their ecological and overwintering characteristics both before and after overwintering, i.e., in dormant and non-dormant state: non-carnivorous Hydrocharis morsus-ranae and Caldesia parnassifolia and carnivorous Aldrovanda vesiculosa, Utricularia australis, U. ochroleuca, and U. bremii, and in non-dormant winter apices of three Australian (sub)tropical populations of Aldrovanda and of two temperate North American Utricularia species, U. purpurea and U. radiata. Respiration rate of autumnal (dormant) turions at 20°C ranged from 0.36 to 1.3 μmol O₂ kg⁻¹ (FM) s⁻¹ and, except for U. bremii, increased by 11–114% after overwintering. However, this increase was statistically significant only in two species. Respiration Q₁₀ in dormant turions ranged within 1.8–2.6 and within 2.3–3.4 in spring (non-dormant) turions. Turions of aquatic plants behave as typical storage, overwintering organs with low respiration rates. No relationship was found between respiration rate of turions and overwintering strategy. In spite of their low respiration rates, turions can usually survive only from one season to another, due to their limited reserves of respiratory substrates for long periods. Contrary to true turions, respiration rates in non-dormant winter apices both in Australian Aldrovanda populations and temperate U. radiata and U. purpurea, in sprouting turions, and growing shoot apices of Aldrovanda were high and ranged from 2.1 to 3.1 μmol kg⁻¹ (FM) s⁻¹, which is comparable to that in aquatic plant leaves or shoots.     

Seasonal abundance of the neotropical brown stink bug, Euschistus heros, in overwintering sites, and the breaking of dormancy

The seasonal abundance of the neotropical brown stink bug, Euschistus heros (Heteroptera: Pentatomidae), in overwintering sites in northern Paraná state, Brazil (latitude 23°11 S, longitude 51°11 W) was monitored from September 1994 to August 1995. The breaking of dormancy (oligopause) was studied in the laboratory by comparing the feeding activity and reproduction of adults collected in the field under different physiological conditions (i.e., dormant and non-dormant). No bugs were found in overwintering sites during the summer (December to February) and during early autumn (March). From mid-autumn to winter (April – August), the number of E. heros captured in these sites gradually increased, decreasing thereafter with the start of spring in September. Dormant and non-dormant E. heros taken to the laboratory and maintained at 25 ± 1 °C , 65± 5% r.h., and L14: D10 photoperiod, and given suitable food (soybean pods or seeds), began feeding immediately. The number of stylet sheaths deposited/day on the food was greater for non-dormant than for dormant adults. Feeding activity was greater on immature pods than on mature seeds of soybean. Dormant females placed under suitable biotic and abiotic conditions took ca. 2 weeks to start reproduction, in contrast to non-dormant females, which reproduced immediately.     

Seasonal growth rate and population dynamics of a freshwater sponge

Five sites of various water depths on four transects were sampled on a seasonal basis to determine Ephydatia fluviatilis population dynamics. The temporal occurrence of life cycle events was influenced by factors (e.g. water temperature) that varied with water depth. The shallow-water (< 1.0 m deep) portion of the population was characterized by seasonal standing crop fluctuations and fall gemmulation. Gemmulation was rare and standing crop relatively constant in the perennial deep water (>1.5 m deep) portion of the population. Sexual reproduction occurred in the spring. Seasonal growth rates were determined for 45 E. fluviatilis colonies on 6 rocks. Growth was maximal during late spring and summer at a mean rate of 26.75% increase in area per week. Growth rates during the winter were slow (2.0% increase/ week). Growth rates were not significantly different between small (<4.0 mm²) and large (>4.0 mm²) colonies. Seasonal changes were positively correlated with colony growth rates, whereas, micro-habitat parameters that may vary from rock to rock within a small area were not correlated.     

Seasonal periodicity of aquatic fungi in tanks at Kurukshetra,India

The occurrence, distribution and seasonal periodicity of 49 species of aquatic fungi belonging to the orders Chytridiales, Lagenidiales, Blastocladiales, Saprolegniales and Peronosporales from two tanks of Kurukshetra, India, is described. Seasonal periodicity was found to be governed by temperature.     

越冬代棉大卷叶螟的种群动态

对棉大卷叶螟Sylepta derogata Fabricius第5代、第6代室内种群饲养结果显示,该虫的有效越冬虫源为第5代滞育的老熟幼虫,滞育率24.4%～33.1%,第6代棉大卷叶螟的发生对第2年的种群基数影响不大。滞育老熟幼虫的越冬存活率为60.0%～71.9%。次年越冬代羽化的成虫雌虫少,雄虫多,单雌产卵量平均为163.4～198.8粒。     

Actin dynamics at sites of extracellular matrix degradation

The degradation of extracellular matrix (ECM) by proteases is crucial in physiological and pathological cell invasion alike. In vitro, degradation occurs at specific sites where invasive cells make contact with the ECM via specialized plasma membrane protrusions termed invadopodia. Here we present an extensive morpho-functional analysis of invadopodia actively engaged in ECM degradation and show that they are actin comet-based structures, not unlike the well-known bacteria-propelling actin tails. The relative mapping of the basic molecular components of invadopodia to actin tails is also provided. Finally, a live-imaging analysis of invadopodia highlights the intrinsic long-term stability of the structures coupled to a highly dynamic actin turnover. The results offer new insight into the tight coordination between signalling, actin remodelling and trafficking activities occurring at sites of focalized ECM degradation by invadopodia. In conclusion, invadopodia-associated actin comets are a striking example of consistently arising, spontaneous expression of actin-driven propulsion events that also represent a valuable experimental paradigm.     

Spontaneous firings of carnivorous aquatic Utricularia traps: temporal patterns and mechanical oscillations

Aquatic species of Utricularia are carnivorous plants living in environments poor in nutrients. Their trapping mechanism has fascinated generations of scientists and is still debated today. It was reported recently that Utricularia traps can fire spontaneously. We show here that these spontaneous firings follow an unexpected diversity of temporal patterns, from "metronomic" traps which fire at fixed time intervals to "random" patterns, displaying more scattered firing times. Some "bursting" traps even combine both aspects, with groups of fast regular firings separated by a variable amount of time. We propose a physical model to understand these very particular behaviors, showing that a trap of Utricularia accomplishes mechanical oscillations, based on continuous pumping and sudden opening of the trap door (buckling). We isolate the key parameters governing these oscillations and discuss the effect of their fluctuations.     

飞蝗越冬卵过冷却点的季节性变化及生态学意义

运用热电偶方法测定了飞蝗LocustamigratoriaL .越冬卵过冷却点月份间的变化。结果表明 :飞蝗卵的过冷却点值波动较大 ,主要形成 2部分 ,一部分分布在 -2 5℃左右 ,另一部分分布在 -1 0℃左右 ,同时 ,这两部分的比例随着季节性气温的变化有明显的差异 ,气温较低的月份 ,-2 5℃左右的比例增加 ,而且最小过冷却点的值也更低 ;反之 ,-1 0℃左右的比例增加 ,过冷却点最高值也升高。这种现象说明了飞蝗卵对冬季低温的一种生态适应。     

Seasonal growth dynamics of Siberian spruce ectomycorrhiza and sugar content in it

Seasonal growth, dynamics of morphological and anatomical structure, and sugar content in ectomycorrhizal roots of Siberian spruce (Picea obovata Ledeb.) were studied. A variability of the root tip structure related to variations in hydrothermal conditions in soils of spruce phytocenoses was observed. A high content of mono- and disaccharides was detected in root tips in the beginning and end of the growth season. Changes in the growth pattern of spruce mycorrhizal roots were associated with changes in the sugar concentration in them, the thickness and volume of the mycelium sheath, and respiration.     

福州茶园节肢动物群落季节消长研究

通过在福建农林大学园艺学院教学实习茶园的系统调查表明:共查得节肢动物2纲、18目、90科、152属、169种.其中:害虫(包括螨类)2纲、9目、40科、74属、77种;中性昆虫3目、7属、8～10种;天敌(不包括肉食性益螨在内)2纲、11目、47科、73属、83种.茶园节肢动物的群落由于生态环境较好,较少使用化学农药,虽然各类节肢动物的种类较多,可是种群数量较少,年中多数时间均处于较好的平衡状态,它们的多样性指数、均匀度指数波动不大.茶园节肢动物群落的种群数量可受季节、气候、茶树生长和采摘等因素影响,冬季11月至早春3月节肢动物越冬期间,它们的种群数量较少;随着春季气温回升,茶园节肢动物群落的种群数量也逐渐增加;5～10月茶树生长旺季,节肢动物的种群数量也处于繁衍活跃时期;10月以后因气温下降,茶园节肢动物的生长活动也相应减缓,直至越冬阶段种群数量日渐减少.茶园天敌与害虫的种群数量消长趋势基本相似,天敌的数量消长呈现一定的跟随现象.     

Physical and chemical control of released microorganisms at field sites

An important consideration in the environmental release of a genetically engineered microorganism is the capability for reduction or elimination of microorganism populations once their function is completed or if adverse environmental effects are observed. In this study the decontamination treatments of burning and biocide application, alone and in combination with tilling, were evaluated for their ability to reduce populations of bacteria released on the phylloplane. Field plots of bush beans (Phaseolus vulgaris), sprayed with the bacterium Erwinia herbicola, received the following treatments: control; control + till; burn; burn + till; Kocide (cupric hydroxide); Kocide + till; Agri-Strep (streptomycin sulfate); and Agri-Strep + till. Leaves and soil from the plots were sampled -1, 1, 5, 8, 12, 15, 19, and 27 days after application of the decontamination treatments. Burning produced a significant reduction in the number of E. herbicola, whereas tilling, alone or in combination with the biocide treatments, stimulated a significant increase in E. herbicola populations, which persisted for several weeks. The individual treatments of the biocides, Kocide and Agri-Strep, produced a rate of decline in E. herbicola populations that did not significantly differ from that of the control treatment.     

稻鸭共作有机稻田蜘蛛多样性与飞虱数量的季节动态

为探究有机农田害虫治理途径和方法,对华东中晚稻区稻鸭共作有机稻田以及常规对照稻田(根据杀虫剂施用量不同分为Ⅰ和Ⅱ)的蜘蛛和飞虱数量动态进行了连续2年的全季节系统调查.结果显示:蜘蛛由9～10科组成,Shannon多样性指数依次为常规稻田Ⅱ＞常规稻田Ⅰ＞有机田,而Simpson集中优势性指数均为有机田最高;3类稻田蜘蛛个体数量的季节变化动态比较一致,在水稻生长的早期,有机稻田中的蜘蛛个体数量低于常规稻田Ⅰ和常规稻田Ⅱ,水稻生长的中、后期则相反.有机稻田中飞虱个体数量的季节波动比较大,而常规稻田Ⅰ和常规稻田Ⅱ中飞虱数量的季节变化不明显;有机稻田飞虱个体数量显著高于常规稻田Ⅰ和常规稻田Ⅱ,但蜘蛛个体数量差异不显著;有机稻田中蜘蛛个体数量跟随飞虱个体数量变化比较明显,而常规稻田Ⅰ和常规稻田Ⅱ则不明显.两年的数据表明,蛛虱比的最低值都出现在有机稻田,而整个生育季节的蛛虱比也为有机稻田低于常规稻田Ⅰ和常规稻田Ⅱ.研究结果说明,有机作物种植中害虫治理面临严峻挑战,需要探索切实可行的生态学治理新方法.     

Soil fertilization enhances growth of the carnivorous plant Genlisea violacea

In a 116-d greenhouse growth experiment on a terrestrial carnivorous plant Genlisea violacea (Lentibulariaceae), mild fertilization of a peaty soil led to a 2.4 fold increase in total plant biomass as compared to the controls. Tissue P and K content in fertilized plants was significantly higher than that in the controls.     

Antibody dynamics of carnivorous mammals and corvine birds infected with Francisella tularensis

The time course of antibody formation in carnivorous mammals and corvine birds infected with a single injection of F. tularensis has been experimentally studied in the agglutination test and the passive hemagglutination test. In carnivorous mammals the allergic transformation of the body has been established by means of the leukocytolysis test.