A laboratory study on temperature relations of egg production and development in two related species of carabid beetle

Summary Egg production and development of the carabid beetles Notiophilus biguttatus F. and Notiophilus rufipes Curtis were studied in relation to temperature. Adult beetles and larvae were fed springtails of the species Orchesella cincta (Linné). The rate of egg production, at the different temperatures did not differ between the species. As observed in N. biguttatus egg production at a daily fluctuating temperature regime is high compared to egg production at the constant temperatures. Food supply not only has a strong effect on egg production but also on the relation of egg production with temperature, as shown in N. biguttatus. Development times in N. rufipes are longer than in N. biguttatus particularly at low temperatures. The temperature during development has a distinct effect on adult body size. As observed in N. biguttatus body size and fecundity show a strong positive correlation.     

The carabid communities on peat and upland grasslands in northern England

During a two year period 13498 individuals of 66 species of carabids were taken from 44 sites on peat and upland grasslands over an altitude range of 11-847 m in the north of England. The similarities between the carabid faunas of each site have been assessed using a modified form of the Sørensen's Index and the sites clustered according to their similarities. Five carabid communities on peat and three on mineral soils have been identified and the more abundant species have been used to characterise them. Peat Community I occurs on dry heath and is characterised by peat associated species such as Trichocellus cognatus and Bradycellus ruficollis together with widespread open habitat species such as Pterostichus madidus, Notiophilus aquaticus, Calathus melanocephalus and Nebria salina. Peat Community II is found on areas where dry heath and deep wet peat are adjacent and is characterised by the species already mentioned together with typical wet habitat species such as Pterostichus diligens, P. nigrita, Patrobus assimilis. Agonum fuliginosum. Peat Community III is found on blanket bog and is characterised by the wet habitat species in the absence of the species present on the dry heath. Peat Community IV found on the lowland oligotrophic mires is characterised by the small number of species present and the addition of Pterostichus niger and Agonum ericeti to the few wet habitat species present. Peat Community V, on the scarp slope of Dun Fell, consists of the wet habitat species of Peat Community III together with Pterostichus madidus. Nebria salina, Notiophilus aquaticus and Calathus melanocephalus. Grassland Community I, on the fell tops, is characterised by the presence of Nebria gyllenhali, Notiophilus germinyi and Patrobus assimitis. Grassland Community II and III are less clearly defined but Grassland Community II may be present on wetter sites than III and is characterised by the presence of Pterostichus nigrita, P. diligens and P. strennus together with Notiophilus biguttatus. N. aquaticus, Pterosfichus madidus and Patrobus afrorufus. Grassland Community III consists of the latter group of species together with Nebria salina, Calathus melanocephalus and Notiophilus aestuans. The number of grassland sites studied was small and there may be further communities on the upland grasslands.     

The Significance of Oxygen Transport and of Metabolic Adaptation in Flood-Tolerance of Senecio Species

Experiments were designed to provide information about the physiological basis of flood-tolerance in Senecio species. The oxygen concentration in roots of S. jacobaea L., S. viscosus L. and S. vulgaris L. became almost zero after transplantation to a solution of low oxygen concentration, and it was concluded that the flood-sensitivity of these Senecio species could be due to insufficient oxygen transport from the shoots to the roots. The oxygen concentration in the roots of the flood-tolerant S. congestus (R.Br.) DC., growing in a solution of low oxygen tension, was almost sufficient to maintain oxygen utilization at the rate observed in roots of plants, grown in an air-saturated solution. Oxygen utilization by roots of the flood-tolerant S. aquaticus Hill, growing in a solution of low oxygen tension, was inhibited 50%. However, the oxygen concentration in the roots of this species remained high enough to maintain cytochrome oxidase activity and oxidative phosphorylation at the rate observed in roots from an air-saturated environment. The activity of a second (“alternative”) oxidase must have been drastically reduced. Alternative NADH-oxidizing enzymes, like nitrate reductase which was induced by anaerobiosis in roots of S. aquaticus, might replace the regulatory function of the alternative oxidase. — Thus, in S. aquaticus root porosity and root length contributed to the maintenance of an oxygen concentration which was sufficient for uninhibited cytochrome oxidase activity and oxidative phosphorylation rate in roots growing in a solution of low oxygen tension.     

The predation on Asellus aquaticus (L.) by perch,Perca fluviatilis (L.), in a small forest lake

Asellus aquaticus (L.) was the most important benthic food item for perch, Perca fluviatilis (L.), in a small, extremely humic forest lake in southern Finland. The proportion of A. aquaticus in the diet of perch varied according to the former's availability, which, in turn, depended on its life cycle. Perch 11.0–12.9 cm (total length) most frequently fed on A. aquaticus; smaller and larger perch fed more frequently on crustacean zooplankton and aquatic insect larvae, respectively. The high density of the perch population, the importance of A. aquaticus in the benthos of the study lake and the general high activity level of the prey resulted in a high predation (0.1–1.8% per day). The population of A. aquaticus was also limited by the scarcity of macrophytic vegetation and the small area of oxygenated littoral in the lake.     

Comparative ecology of Gammarus pulex (L.) and Asellus aquaticus (L.) I: population dynamics and microdistribution

Gammarus pulex and Asellus aquaticus generally occupy different zones in rivers; the former occurs in upper reaches but is replaced by the latter in lower reaches. Microdistribution and life-history patterns of G. pulex and A. aquaticus in sympatry and allopatry, were analyzed. Both species exhibited similar patterns of microhabitat selection, with larger individuals associated predominantly with large-sized substratum particles, and juveniles with weed. Coexisting populations of G. pulex and A. aquaticus had similar densities and population dynamics. Within each species, differences in population dynamics of allopatric and sympatric populations were observed. Although variation in population dynamics of G. pulex may be explained in terms of competition between the two species, the evidence is weak and equivocal. Differences in the dynamics of the two A. aquaticus populations were possibly a consequence of coal-mine and organic pollution, reducing the survival of offspring in the allopatric population.     

Respiration and NADH-Oxidation of the Roots of Flood-Tolerant and Flood-Intolerant Senecio Species as Affected by Anaerobiosis

Respiration was measured under anaerobiosis in the roots of two Senecio species: S. aquaticus Hill, which is flood-tolerant, and S. jacobaea L., which is flood-intolerant. NADH-oxidation under anaerobiosis was measured in roots of S. aquaticus, S. jacobaea and S. vulgaris L., which is also flood-intolerant. Protein content of S. aquaticus was about 15% higher under anaerobiosis. At 20°C respiration of the roots of S. aquaticus was 50% inhibited under anaerobiosis, while an almost complete inhibition occurred in the roots of S. jacobaea. The activities of nitrate reductase, glutamate dehydrogenase and lactate dehydrogenase were considerably higher in the roots of S. aquaticus grown under anaerobic conditions than in roots grown under aerobic conditions. In S. jacobaea glutamate dehydrogenase activity was lower and in S. vulgaris nitrate reductase was lower and glutamate dehydrogenase activity was higher in roots grown under anaerobic conditions. The possible role of these enzymes for metabolism under anaerobic conditions by oxidizing a surplus of NADH is discussed. Since oxidative phosphorylation is 50% inhibited under anaerobiosis, ATP has to be generated in a different way. It is argued that maintenance of the ATP-level may be compensated by way of the enzymes mentioned above, in combination with a modified glucose utilization.     

Diel activity patterns of some field Carabidae

Abstract. 1. A 24 h time-sorting pitfall trap was used to collect Carabidae in a field in north-east England in 1974, 1976 and 1977.
2. Harpalus rufipes comprised 62% of the 5288 adult Carabidae caught. It was nocturnal, with an activity peak after midnight. The male activity pattern lagged behind that of females by about 1 h. The activity peak shifted to earlier in the night during September.
3. Activity curves are given for eighteen other common species. Large species were all nocturnal, but a third of the smaller species were active in the day. The numbers caught of twenty-eight less common species are tabulated and show the same trend. Overall, nearly 60% of all species caught were nocturnal and 20% diurnal; the remainder did not show a distinct pattern of day or night activity.
4. A total of eighty-two larvae of H.rufipes, Nebria brevicollis and Notiophilus biguttatus were caught, and showed similar activity patterns to those of the respective adult beetles.     

Respiration of Senecio Shoots: Inhibition during Photosynthesis, Resistance to Cyanide and Relation to Growth and Maintenance

Respiration and dry matter producation were measured in shoots of senecia aquaticus Hill, which is flood tolerant and in shoots of S. jacobaea L., which is flood- sensitive. Both species were grown in culture solutions of high and of low oxygen concentration Growth of food of S. jacobaca was unaffected by a low oxygen supply bur growth of S. jacobaca was severly hampered by a low oxygen concentration in the root medium. Kinetic data about the rate of apparent photosynthesis at low oxygen conetration and different carbon dioxide concentrations indicated that at light saturation respiration was strongly repressed during photosynthesis. Shoot growth respiration, i.e. the amount of carbon dioxide produced for synthesis of shoot dry, matter appeared to be absent on S. jacobaea and to be very low (13.mg CO₂/g dry shoots) in S. aquaticus. In comparison with values prepiration rate was 2.8. 2.0. 1.5 and 1.3mg CO₂/h.g dry shoots in aerobically and anaerobically growth S. jacobaea and in aerobically and anaerobically growth S. aquabaea respectively. These values were also low in comprision with values previously found for roots of the same species. Shoot dark respiration on S. aquaticus was inbihitedd by a com bination on CN and salicylhydroxamic acid (SHAM), but not by application on one of these inhibitors alone. It was therefore concluded that an alternative oxidative pathway was present but not active in shoots of S. aquaticus. In the absence of inhibited of the cylochorome pathway. The low value of growth respiration and maintenance respiration rate in the shoots as compared with those in the roots of the investigated Sencio species are discussed in relation to the activity of the alternative oxidative pathway and to the possibilbity of a direct supply of ATP by photosynthesis intead of respiratory meta bolism.     

Tree–herb co-existence and community assembly in natural forest-steppe transitions

Background: Hybridisation between locally common and rare plant species is of conservation concern as it may lead to the extinction of the rare taxon. Rumex aquaticus (2n = ca. 200, Polygonaceae) is a widespread Euro-Siberian species but rare in the British Isles. It hybridises freely with the locally abundant congener R. obtusifolius (2n = 40) producing fertile and viable hybrids.

Aims: We aimed to establish whether hybridisation poses an extinction threat to R. aquaticus in Britain.

Methods: Flow cytometry, AFLPs and morphological characters were used to assess the extent of hybridisation between R. obtusifolius and R. aquaticus.

Results: Flow cytometry was the most useful tool to distinguish between hybrids and parental species and indicated that out of 88 samples from two hybrid populations, 85% were likely to be F1s and only 15% were likely to be back-crosses to R. aquaticus. AFLP markers were only able to identify putative F1 hybrids reliably and 11 morphological traits could not distinguish unambiguously between hybrids and pure R. aquaticus.

Conclusions: Although our data suggest that genetic assimilation of pure R. aquaticus populations is unlikely to be the case in the future, there is a potential threat from demographic swamping by hybrids and targeted protection of R. aquaticus habitat is proposed as a management strategy.     

Efficiency of Root Respiration of a Flood-Tolerant and a Flood-Intolerant Senecio Species as Affected by Low Oxygen Tension

A method was described to determine root growth respiration and root maintenance respiration rate of plants, grown in culture solutions of high and low oxygen concentrations, during linear growth. Root growth respiration of aerobically grown plants was three to four times lower in the flood-intolerant Senecio jacobaea L. than in the flood-tolerant species. Senecio aquaticus Hill. Root growth respiration of Senecio aquaticus Hill decreased by a factor two to three upon transplantation to a culture solution of low oxygen tension. The difference in root growth respiration between aerobically and anaerobically grown Senecio aquaticus Hill was ascribed to the presence of a highly active non-phosphorylating oxidase.     

Processing of leaf matter by lake-dwelling shredders at low oxygen concentrations

Organic sediments in freshwaters are regularly subject to low concentrations of oxygen. The ability of detritivores to sustain their feeding in such conditions should therefore be of importance for the decomposition process. In the present study, aquaria were used to determine processing rates of five lake-dwelling shredders at three different oxygen concentrations; normoxic (9 mg O₂ l^–1) and two levels of hypoxia (1 and 2 mg O₂ l^–1). Discs of alder leaves (Alnus glutinosa (L.)) were used as food. Four species of caddisfly larvae (Trichoptera Limnephilidae) and the isopod, Asellus aquaticus (L.) were compared in the experiments. Significant differences in processing rates per g animal biomass were found both at normoxia and 2 mg oxygen l^–1. At l mg O₂ l^–1 none of the invertebrates fed on leaf discs. The caddisfly larvae Halesus radiatus (Curtis), being one of the two most efficient shredders at normoxia, did not feed at 2 mg oxygen l^–1. The other species fed at rates 15–50 of that at normoxia. The least efficient shredder at normoxia, A. aquaticus was similar to two of the trichopterans at 2 mg O₂ l^–1. This study shows that the importance of specific shredder species may shift in case of hypoxia. Species-specific traits regarding oxygen sensitivity may also be influential for distribution patterns of shredder species both within and between lakes.     

Studies on two species of Asellus in Rutland Water

The study comprised a comparison of the ecology of two species of Asellus (A. aquaticus and A. meridianus), and had two main aims. First the energy budget of the population of A. aquaticus, which is one of the most abundant species in the reservoir was assessed. Secondly, the two species appear to be ecologically very similar and it has been assumed by many workers that they are in competition. The study aimed to investigate how these two species might be able to coexist.The population dynamics of both species and the interaction between them is under study, as are their relations with the other benthic animals recorded in the reservoir (see Bullock et al. 1982). The sampling programme to cover variations in depth and substratum is also described by Bullock et al. 1982. A. aquaticus occurs in both arms while A. meridianus exists only in the south arm. A preliminary examination of the available data reveals that the density of A. aquaticus has increased in the south arm while the density of A. meridianus decreased drastically in February 1980. Since then low numbers of A. meridianus have been recorded every month even in the summer (breeding) season. It is noteworthy that simultaneously the number of predators, particularly Helobdella stagnalis, increased in comparison with previous years.It was therefore decided to study the predation on Asellus in the laboratory as well as in the field by using a serological technique. Antisera were produced against each species of Asellus by injections into rabbits of precipitated proteins (antigens). Thus a positive reaction obtained from a homogenised predator when tested with the specific antiserum indicates which species of Asellus had been consumed and the percentage of predators which had fed on Asellus in every sample could be calculated. The results obtained to date reveal that considerable numbers of Asellus spp. are removed from the environment by the predators (Helobdella stagnalis, Erpobdella octoculata, Polycelis tenuis. Dendrocoelum lacteum and Dugesia lugubris).Size class structures of the population of both species were constructed to study their life cycles and to estimate the population production. Comparitive respirometry of the two species was carried out at 4 °C, 10 °C and 16 °C, using a Gilson differential respirometer. This study aimed firstly to assess one of the essential parameters in the energy budget study of A. aquaticus and secondly, since A. aquaticus appears to be more active than A. meridianus, it would be expected that a comparison of their metabolic rate at different temperature would reveal marked differences between two species. It was found that there was no significant difference between the two species at 4 °C and 10 °C, but A. aquaticus had a significantly higher metabolic rate than A. meridianus at 16 °C.Consumption and assimilation of decaying oak leaves and of Cladophora glomerata (both of which are available in the environment) by two species of Asellus are being measured at present in the laboratory at three different temperatures (4 °C, 10 °C and 16 °C), and will contribute to the estimation of energy budgets.     

The relevance of the brightness to visual acuity,predation, and activity of visually hunting ground-beetles (Coleoptera,Carabidae)

Summary Carabid species of the visually hunting type living in dim habitats have larger frontal ommatidia and gain their optimal visual performance with lower light intensity than species inhabiting bright places.The latter phenomenon is based upon the mechanisms of light adaptation, which reduce the acceptance angles of the ommatidia thus increasing their visual acuity. In more sensitive ommatidia adaptation occurs with lower light intensity.The differences between the species concerning the intensity dependence of their visual performance are regarded as an effect of natural selection. Thereafter an apposition eye more sensitive to light should be advantageous in a dim environment.This hypothesis has been investigated and verified by observation of the predation behaviour of Notiophilus biguttatus confronted with Collembola: From 1 to 500 lux the hunting success of the beetles increased proportionally to the light intensity.Measurements of the activity at dawn and at dusk under natural conditions showed that the beginning and the conclusion of activity are correlated with a critical level of illumination. Notiophilus biguttatus starts being active if the illumination is sufficient for successful hunting.Supported by the Deutsche ForschungsgemeinschaftSupported by the Österreichischer Forschungsrat     

Occurrence of Senecio aquaticus in relation to grassland management

Background: Senecio aquaticus is an esteemed wetland species, but it is also a poisonous species in grasslands for forage production of various countries (e.g. Great Britain and Central European states), and its further spread onto farmland must be prevented. To reveal links between management practice and the occurrence of S. aquaticus, a survey was carried out on agricultural grassland in the summer of 2005. Location: The mountain region in the northern and central part of Switzerland. Methods: Botanical assessments were carried out on management units (parcels) where S. aquaticus occurred and on neighbouring parcels without occurrence. For all parcels, we analysed the soil nutrients and the details of management such as intensity of fertilisation and defoliation frequency. Results: There was a high risk of S. aquaticus occurrence in parcels with low nitrogen fertilisation, a change of management intensity in the preceding 15 years, high inclination, and gaps in the sward. The change in the vegetation composition caused by altering the management intensity most probably provided gaps in the sward, which were then colonised by S. aquaticus. A novel finding is that, despite its preference for low‐nutrient sites, the species was also persistent at sites with a moderate to high management intensity. Conclusion: A long‐term control of S. aquaticus on agricultural grasslands can best be achieved by avoiding sward damage and by promoting dense and stable swards. The management should be adjusted to the local environmental conditions and the requirements of the favourable plant species. This could prevent the spread of S. aquaticus from the protected wetlands onto agricultural grasslands, where the species would threaten animal health.     

Ribotyping of 16S and 23S rRNA genes and organization of rrn operons in members of the bacterial genera Gemmata,Planctomyces, Thermotoga,Thermus, and Verrucomicrobium

The number of organization of rrn genes of two members of the order Planctomycetales, Planctomyces limnophilus and Gemmata obscuriglobus, as well as three species from other bacterial phyla, namely Thermotoga maritima, Thermus aquaticus and Verrucomicrobium spinosum were examined by Southern blot hybridization analysis of restricted DNA with labeled 16S- and 23S rRNAs. Ribotyping analysis revealed that two species contain unlinked 16S- and 23S rRNA genes. Planctomyces limnophilus possessed two unlinked rrn genes which were separated from each other by at least 4.3 kb, and Thermus aquaticus had to unlinked 16S and 23S rRNA genes, separated from each other by at least 2.5 kb. Gemmata obscuriglobus exhibited five genes for which the organization could as yet not be determined because of the complex hybridization patterns. In the other two species, rrn genes clustered in operons. Thermotoga maritima had a single gene for each rRNA species which were separated by not more than 1.5 kb, while Verrucomicrobium spinosum had four copies of probably linked 16S and 23S rRNA genes with a maximal distance between 16S and 23S rRNA genes of 1.3 kb.     

Ecological aspects of thermoregulation at high altitudes: the case of andean Liolaemus lizards in northern Chile

Summary We document activity field temperatures, daily activity patterns, and extent of thermoregulation in four species of Liolaemus lizards inhabiting at high altitude (above 3500 m) in the Andes of northern Chile. These four species have similar activity field temperature (Tb near 29°C) despite their being distributed at different altitudinal belts. However, conspicuous differences exist between higher-altitude (L. alticolor and L. jamesi) and lower-altitude (L. islugensis and L. ornatus) lizards regarding extent of thermoregulation and activity period. Some differences in morphology, behavior, and patterns of microhabitat occupancy are also apparent among these four species and are seemingly related to the thermal environment to which they are subjected. In comparison to eight low-altitude Liolaemus species in central Chile (Tb near 35°C) the four high-altitude species in northern Chile have lower activity field temperature. The latter is apparently due to the constraints imposed by the harsh Andean thermal environment, a hypothesis supported by the fact that high-altitude Liolaemus lizards under laboratory conditions demonstrate body temperatures that exceed by 5°C or more, those recorded in the field.     

Acute Toxicity for some Evaporating Aromatic Hydrocarbons for Freshwater Snails and Crustaceans

Some typical and more frequent freshwater invertebrates of running waters were studied to examine the influence of styrene, xylene and benzene on their mortality. Snails Amphimelania holandri FÉR. and Lymnaea stagnalis L. and crustacenas Asellus aquaticus L. and Gammarus fossarum KOCH. , were used in the semi-static test. Compounds were added in volume concentrations of 0.005 to 0.4% v/v. For all concentrations LC₅₀ was calculated by probit method, which demonstrated that mortality depends much more on increased concentrations (depending on the initial concentration) than on the length of exposure. Styrene was the most toxic, followed by xylene and then benzene. The species G. fossarum showed marked sensitivity, followed by A. aquaticus, and the species A. holandri and L. stagnalis showed less sensitivity.     

Daily and seasonal activity in woodland ants

Summary Daily and seasonal foraging patterns are described for nine species of ants occupying a temperate zone woodland. Two common dominant species, Prenolepis imparis and Formica subsericea, are active at different times of day and during different parts of the year. They appear to be limited by physical factors (temperature and light, respectively) while the subordinate species show a wider tolerance of physical conditions. The subordinate species exhibit peak foraging periods which overlap in large part with most dominant species. This temporal pattern of species activity is discussed in relation to the competitive relationships within this ant guild.     

Surface spreading of synaptonemal complexes in three isopod crustacean species

The technique of whole mount spreading is used to investigate the SC of three species of Asellidae (isopod crustaceans), Asellus aquaticus, Proasellus coxalis and Proasellus meridianus, which display considerable differences in genomic DNA content.The three species, originally considered to belong to the same genus Asellus, were subsequently assigned to two separate genera: Asellus and Proasellus. The SCs of the three species differ in morphological details related to the shape of the centromere region, the attachments to the nuclear envelope, the width of the central region and the presence of twists of the lateral elements. Furthermore, they display some differences in the degree of compaction of genomic DNA in the mitotic chromosomes. The greatest differences are found between A. aquaticus and P. coxalis, while P. meridianus has several features in common with either species.