How does the body-scale model affect back-calculated growth: the example of arctic charr Salvelinus alpinus (L.) of Lake Geneva (Switzerland)

When back-calculating fish length from scale measurements, the choice of the body-scale relationship is a fundamental step. Using data from the arctic charrSalvelinus alpinus (L.) of Lake Geneva (Switzerland) we show the need for a curvilinear model, on both statistical and biological grounds. From several 2-parameters models, the log-linear relationship appears to provide the best fit. A 3-parameters, Bertalanffy model did not improve the fit. We show moreover that using the proportional model would lead to important misinterpretations of the data.

Optimizing a remotely sensed proxy for plankton biomass in Lake Kivu

Many regions of the world, including inland lakes, present with suboptimal conditions for the remotely sensed retrieval of optical signals, thus challenging the limits of available satellite data-processing tools, such as atmospheric correction models (ACM) and water constituent-retrieval (WCR) algorithms. Working in such regions, however, can improve our understanding of remote-sensing tools and their applicabil- ity in new contexts, in addition to potentially offering useful information about aquatic ecology. Here, we assess and compare 32 combinations of two ACMs, two WCRs, and three binary categories of data quality standards to optimize a remotely sensed proxy of plankton biomass in Lake Kivu. Each parameter set is compared against the available ground-truth match-ups using Spearman's right-tailed ρ. Focusing on the best sets from each ACM-WCR combination, their performances are discussed with regard to data distribution, sample size, spatial completeness, and seasonality. The results of this study may be of interest both for ecological studies on Lake Kivu and for epidemio- logical studies of disease, such as cholera, the dynamics of which has been associated with plankton biomass in other regions of the world.

Muchakinock Creek: Improving Water Quality for the Future, 2005

History has taken its toll on Muchakinock Creek. A number of problems over the years have led to the stream’s current state, one that’s landed it on Iowa’s list of impaired waters. However, the stream is also full of opportunity. The opportunity to improve water quality not only for the aquatic life and wildlife that live there, but also to pass along clean water to future generations of Iowans. But to act on this opportunity, we need your help.

Repairing the Impaired: Two Iowa Success Stories, 2005

More than 200 lakes, streams and rivers are on Iowa’s impaired waters list. Pollutants prevent these waters from supporting aquatic life, or from being used for drinking water or for full body recreational contact, like swimming. While improving Iowa’s water quality may seem a daunting task, two southern Iowa lakes show that it can be done.

Brushy Creek Lake: Improving Our Lake for the Future, 2006

While the quality of water in Brushy Creek Lake is currently adequate, a number of factors in the watershed (the surrounding area that drains into the lake) could put that water quality at risk. Sediment from the large watershed could fill in the lake and affect water clarity. Nutrients, like nitrogen and phosphorus, could cause algae blooms and other problems. Without preventative measures, potential manure and chemical spills could harm aquatic life in the lake. Using conservation farming practices and building structures like wetlands will work to maintain and even improve the lake’s water quality. Taking steps now to implement these critical practices will help prevent water quality problems, preserving water quality for future generations.

Les paramètres du cycle vital de Physa acuta (Gastropoda, Mollusca) en milieu expérimental.

The values of the life history parameters expressed in the Lotka's equation were measured in the experimental conditions (20ºC, food ad libitum) for the aquatic pumonate Physa acuta. The estimated fitness value allows the population to double in about 4 weeks. The life cycle is very short (about 3 times shorter than for Lymnaea peregra in similar conditions) because of the important relative size of the eggs, a very high growth rate and an early maturity. This kind of strategy seems adaptive in eutrophic and temporary pools, where the adult mortality is important and density-independant. While the longevity shows very poor correlations with all other parameters, adult size, age at maturity and fecundity are strongly correlated. Structural and functionnal interpetations of these correlations are proposed. A mixed strategy seems a good hypothesis for this usually bivoltine species: the little-size, early-maturity and high-fecondity strategy may be selected during the summer, and the big-size, delayed-maturity and poor fecundity strategy during the winter

Parachlamydia acanthamoebae, an emerging agent of pneumonia.

Parachlamydia acanthamoebae is a Chlamydia-like organism that easily grows within Acanthamoeba spp. Thus, it probably uses these widespread free-living amoebae as a replicative niche, a cosmopolite aquatic reservoir and a vector. A potential role of P. acanthamoebae as an agent of lower respiratory tract infection was initially suggested by its isolation within an Acanthamoeba sp. recovered from the water of a humidifier during the investigation of an outbreak of fever. Additional serological and molecular-based investigations further supported its pathogenic role, mainly in bronchiolitis, bronchitis, aspiration pneumonia and community-acquired pneumonia. P. acanthamoebae was shown to survive and replicate within human macrophages, lung fibroblasts and pneumocytes. Moreover, this strict intracellular bacterium also causes severe pneumonia in experimentally infected mice, thus fulfilling the third and fourth Koch criteria for a pathogenic role. Consequently, new tools have been developed for the diagnosis of parachlamydial infections. It will be important to routinely search for this emerging agent of pneumonia, as P. acanthamoebae is apparently resistant to quinolones, which are antibiotics often used for the empirical treatment of atypical pneumonia. Other Chlamydia-related bacteria, including Protochlamydia naegleriophila, Simkania negevensis and Waddlia chondrophila, might also cause lung infections. Moreover, several additional novel chlamydiae, e.g. Criblamydia sequanensis and Rhabdochlamydia crassificans, have been discovered and are now being investigated for their human pathogenicity.

Artrópodos associados à copa de Attalea phalerata Mart. (Arecaceae), na região do Pantanal de Poconé, Mato Grosso, Brasil

Six individuals of the palm A. phalerata, in Poconé floodplains of Mato Grosso, were sprayed with a synthetic pyrethroid (0.25% concentration) in order to study the biomass, diversity, and richness of the canopy arthropods. A total of 17,188 (238.7±80.6 ind./m²) arthropods belonging to 22 Orders, was collected in a 72 m² funnel area. Two hours after spraying, 58.9% of the total number fell into the funnels, 37.6% was obtained by shaking the trees, and finally, 3.5% after cutting and washing all the palm leaves. The Coleoptera (27.4%), Hymenoptera-Formicidae (19.0%), Collembola (13.6%), Psocoptera (10.7%), Diptera (9.0%) and Araneae (6.4%) were the predominant. The total biomass was 15.1 g dry weight (0.4mg/m²; 0.13+0.04/tree). A total of 4,715 beetles representing 48 families and 326 morphospecies were obtained. Tenebrionidae (22.9%), Curculionidae (22.0%), Carabidae (10.9%) and Staphylinidae (7.9%) were the most abundant, while Curculionidae (44 spp.), Staphylinidae (40 spp.) and Chrysomelidae (34 spp.) presented the largest number of morphospecies. Herbivores (37.5%) were the dominant in the trophic guilds of adult Coleoptera, followed by predators (35.4%), fungivores (14.6%), and saprophages (12.5%). Although most arthropod Orders were represented in all the palms sampled, analysis of variance showed no significant differences in their composition, however there was a significant difference in their frequency of occurrence.

Elytra colour polymorphism and randomness of matings in Chauliognathus fallax Germar 1824 from southern Brazil (Coleoptera, Cantharidae)

Beetles of the species Chauliognathus fallax Germar 1824 are polymorphic for elytron colouration with six morphs distinguished on the basis of black pigmentation on a yellow background. We investigated samples of C. fallax taken in eight consecutive weeks aiming to determine the frequency of the morphs which were grouped, for statistical analysis, into three classes according to elytra pigmentation as well as the possible occurrence of assortative mating. Our results showed a variation in the frequency of the classes throughout the season, both in males and females, with the maximum frequency of each class at the fourth and fifth week. The three classes (A, B, C) showed the same pattern of variation, and class B was always the more frequent. To test randomness of matings two approaches were taken: in the first, we compared the frequency of each class in copulating and non-copulating insects. In the second, the frequency of each class in the whole sample was taken as the probability of occurrence of the respective class; then, using the criterion of the probability of independent events we calculated the expected proportion of copulating insects for each pair of events. Both methods gave non-significant differences, suggesting that the matings were random.

Utilização de bioensaios e marcadores moleculares para detecção da resistência de coleópteros de produtos armazenados a inseticidas

The qualitative and quantitative losses caused by stored product insects are of great concern, and since there is only a few active ingredients available for their control it is very important to have a frequent insect resistance monitoring. The objective of this research is to evaluate combination of bioassays and molecular marker techniques to detect insecticide resistance in stored product beetles. The Coleoptera species used for the tests were Sitophilus oryzae (L.) (Curculionidae), Rhyzopertha dominica (F.) (Bostrichidae) and Oryzaephilus surinamensis (L.) (Silvanidae). For the bioassays it was used the impregnated filter paper technique, applying 1 mL of deltamethrin (K-Obiol 25 CE TM) using four concentrations and five replicates, including a control with solvent only. Ten adults of each species were liberated separately on each dish. The mortality was evaluated after 24 h and resistance determined by probit analysis. The samples used for the PCR-RAPD were either in vivo or preserved in 70% ethanol, kept in -18°C freezer. After extraction, quantification and DNA quality analysis, the 25 µL samples had the DNA amplified and tested with six primers. The bioassays showed a crescent mortality proportional to insecticide concentration. The resistance factor for R. dominica, S. zeamais and S. oryzae were: 2,2; 3,2 and 9,2, respectively, compared to the susceptible populations of each species. The PCR-RAPD analysis revealed bands which indicate inter and intraspecific variability in the populations, but it was not possible to correlate them to resistance. The association of bioassay and PCR-RAPD represents a precise and valuable tool for resistance management of stored product insects, but more populations and primers should be tested.

An illustrated key to nymphs of Perlidae (Insecta, Plecoptera) genera in Central Amazonia, Brazil

An illustrated key to nymphs of Perlidae collected in streams of Central Amazonia, Brazil is provided. Three genera are reported for this region: Macrogynoplax Enderlein, Anacroneuria Klapálek and Enderleina Jewett. Additional diagnostic characters are provided for Enderleina nymphs.

Under- and over-water halves of Gyrinidae beetle eyes harbor different corneal nanocoatings providing adaptation to the water and air environments.

Whirligig beetles (Gyrinidae) inhabit water surfaces and possess unique eyes which are split into the overwater and underwater parts. In this study we analyze the micro- and nanostructure of the split eyes of two Gyrinidae beetles genera, Gyrinus and Orectochilus. We find that corneae of the overwater ommatidia are covered with maze-like nanostructures, while the corneal surface of the underwater eyes is smooth. We further show that the overwater nanostructures possess no anti-wetting, but the anti-reflective properties with the spectral preference in the range of 450-600 nm. These findings illustrate the adaptation of the corneal nanocoating of the two halves of an insect's eye to two different environments. The novel natural anti-reflective nanocoating we describe may find future technological applications.

A review of evolution of oviposition guilds in the Bruchidae (Coleoptera)

Three guilds of bruchid beetles oviposit on seeds at different times and in different ways, i. e., in these guilds some species only oviposit on fruits while on the plant (Guild A), other species only oviposit on seeds exposed in fruits while still on the plant (Guild B) and some only oviposit on seeds once they are exposed on the substrate (Guild C). It has been established that one plant species may be oviposited upon by all three guilds, some only by two guilds and some by only one guild. Before and after the inception of this concept many papers have been published that seem to establish that early oviposition behavior of bruchids was probably onto fruits where they burrowed through the fruit wall and fed on seeds (Guild A). Then, as evolution of the fruits developed for dispersal of seeds and possible escape from bruchid predation, bruchids developed to feed in seeds in various other ways (Guilds B and C). Our data show that about 78% of extant bruchids oviposit on fruits, and the other 22% with behavior of Guilds B and C. A review of these papers and new data on oviposition guilds and bruchid evolution are presented and discussed here.

New records of Chironomus Meigen (Diptera, Chironomidae) in the State of São Paulo, Brazil

In this paper seven species of the genus Chironomus Meigen, 1803 are recorded for the first time in the State of São Paulo (Brazil). C. stigmaterus Say, 1823 and C. columbiensis Wülker et al., 1989 are new records for Brazil, while C. calligraphus Goeldi, 1905, C. strenzkei Fittkau, 1968, C. gigas Reiss, 1974, C. latistylus Reiss, 1974 and C. paragigas Reiss, 1974 had already been registered in aquatic systems in North and Northeast regions of Brazil.

Two new species of Goeldichironomus Fittkau from southeast Brazil (Diptera, Chironomidae)

The adult and immature stages of two new species of Goeldichironomus are described and figured. Larvae of G. luridus sp. nov., reared in the laboratory from egg masses, are abundant on organically enriched sediments of a chicken slaughter-house effluent treatment lagoon. Larvae of G. petiolicola sp. nov., live inside petioles of aquatic macrophytes such as Eichhornia azurea and Pontederia lanceolata.