Stable isotopes and gut contents indicate differential resource use by coexisting asp (Leuciscus aspius) and pikeperch (Sander lucioperca)

Differential use of habitat and prey resources is an important mechanism that may allow coexistence of sympatric species. Unlike interactions between smaller cyprinid and percid fishes, the resource use by coexisting predatory asp (Leuciscus aspius) and pikeperch (Sander lucioperca) is relatively unknown. Here, gut content and stable isotope analyses were used to study ontogenetic dietary shifts and interspecific trophic niche overlap between asp and pikeperch coexisting in two reservoirs. The hypothesis that both species show an ontogenetic dietary shift from small invertebrates to large fish prey, but at the same time use different prey resources to reduce potential competitive interactions, was validated. The isotopic niches of the two predators showed no, or only a moderate, degree of overlap (0%–65%). The ontogenetic changes in the degree of interspecific isotopic niche overlap were different in the two reservoirs, suggesting that trophic segregation can be dynamic and variable among systems. Gut contents revealed that small (<100 mm standard length) asp consumed mostly terrestrial invertebrates and emerged aquatic insects, whereas small pikeperch foraged on zooplankton, larval and pupal stages of aquatic insects and fish. Larger individuals (>100 mm) of both species were predominantly piscivorous, with asp consuming more cyprinid prey and pikeperch more percid prey. Coexisting asp and pikeperch populations are able to utilise different prey resources, thereby reducing potential negative competitive interactions.     

Pesticide diversity in rice growing areas of Northern Vietnam

Pesticide use in developing countries increases rapidly. In many regions, we miss knowledge of how frequently pesticides are applied and which active ingredients are used. We present a new cost-efficient and rapid assessment method of recording pesticides diversity in rice-dominated landscapes and present some evidence of the misuse of active ingredients in our study regions. We investigated 17 rice fields in two regions of Northern Vietnam in 2014 and 2015. At each region, we explore the abundance of pesticides used with three methods including (1) the novel approach of collecting pesticide packages close to our target rice fields, (2) observations of farmers spraying pesticides in the surrounding and (3) interviewing local farmers. By collecting pesticide packages, we found 811 packages containing 74 different active ingredients. On average, 19 active ingredients (ranging from four to 40 active ingredients) were applied with an average content of 275.3 g of active ingredients per site. Insecticide packages (39%) were most abundant followed by those of fungicides (31%), herbicides (16%) and other active ingredients (14%). On all sites, active ingredients banned in the European Union were applied by the farmers. Collecting pesticide packages proved to be an efficient and rapidly implemented method to obtain some baseline information about pesticide application (for Northern Vietnam). We suspect that improved agricultural extension services could contribute to good agricultural practices in pest management. Generally, better information and education for local farmers for appropriate use of pesticides seem a necessity.     

Enhancing the parasitism of insect herbivores through diversification of habitat in Philippine rice fields

The diversification of farming landscapes is proposed as a method to increase farm productivity while at the same time enhancing pest regulation services provided by the natural enemies of insect herbivores. In this study, areas of diversified and conventional rice fields (with 2–14 fields per area?=?0.42–1.31 ha) were established at three sites in the Philippines. The diversified areas had a series (>?40 per hectare) of small (<?2 m²) vegetable patches interspersed along rice bunds (levees). The abundance of planthopper and lepidopteran pests in these areas was monitored during two consecutive cropping seasons using sweep nets with rice yield and damage recorded at the end of each season. Mortality of brown planthopper (Nilaparvata lugens) and yellow stemborer (Scirpophaga incertulas) eggs was monitored through field exposures of infested rice plants. There were no differences in rice yields between the conventional and diversified areas; however, a range of vegetables were produced as a supplementary product from the diversified rice areas. Diversification had no effect on planthopper or leaffolder (Cnaphalocrocis medinalis) abundance at the sites. Adult stemborers (Scirpophaga incertulas) were more abundant in the diversified areas; however, stemborer damage was similar between area treatments in both years. Vegetable patches did not increase parasitism of planthopper eggs; however, egg parasitism was highest close to the vegetable patches, suggesting that egg parasitoids interacted with the patches. Mortality of stemborer eggs was higher in the diversified areas than in the conventional areas. Parasitism due to Trichogramma japonicum and other egg parasitoids was also higher in the diversified areas. These results indicate the potential for vegetable patches to enhance the biological control services provided by egg parasitoids in rice fields; however, the study also indicates a need to carefully select vegetable crops that avoid any potential benefits for rice pests. We discuss the need for further research into diversified farms as a means of achieving sustainable rice production in Asia.     

Molecular Variability of the Capsid Protein of the Prune Dwarf Virus

Sequences of the capsid protein gene and the preceding intergenic region of eleven isolates of prune dwarf virus from central Europe were determined. The isolates were obtained from plum, cherry and peach trees. Comparison of all sequenced isolates (including two sequences published previously) revealed high (88%) conservation of the capsid protein gene. The highest degree of identity was observed in the C-terminal half, where only 13 amino acid substitutions could be observed in contrast to the N-terminal half with 22 substitutions. No reasonable correlation between amino acid substitutions and host species and/or geographic origin of the isolates was observed. Alignment with capsid protein genes of other ilarviruses revealed apple mosaic virus, elm mottle virus, lilac ring mottle virus and prunus necrotic ringspot virus as the most related to prune dwarf virus. Unlike the isolates of related prunus necrotic ringspot virus all the isolates of prune dwarf virus shared extensive conservation of the intergenic region. Portions of RNA3 were selected for design of universal primers for PCR detection.     

BMC ecology image competition 2017: the winning images

For the fifth year, BMC Ecology is proud to present the winning images from our annual image competition. The 2017 edition received entries by talented shutterbug-ecologists from across the world, showcasing research that is increasing our understanding of ecosystems worldwide and the beauty and diversity of life on our planet. In this editorial we showcase the winning images, as chosen by our Editorial Board and guest judge Chris Darimont, as well as our selection of highly commended images. Enjoy!     

Trends and controls of Holocene floodplain sedimentation in the Rhine catchment

Holocene floodplain sedimentation in the Rhine catchment is controlled by human and climate impacts. Intricate river behaviour modifies the fluvial response to the external impacts making cause–effect analysis difficult, especially on large spatial scales. To better understand the relative importance and interdependencies of external and internal controls, temporally resolved floodplain sedimentation rates are established using three different methods: i) floodplain storage studies on the trunk stream, ii) depth/age-analysis of overbank deposits from different parts of the catchment and iii) cumulative frequency distributions of ¹⁴C-ages from floodplain deposits from various parts of the catchment. The applied methodology strongly differs with the available temporal resolution and the size of the corresponding catchment. All three methods show a strong increase in sedimentation rate for more recent periods that can be linked to increasing human impact. Evidences for climate impacts and intricate river behaviour are less clear and hindered by insufficient temporal resolution of the currently available data.     

Assessment of somaclonal variability in hop (Humulus lupulus L.) in vitro meristem cultures and clones by molecular methods

In vitro meristem tissue cultures are used for production of virus-free rootstocks of hop (Humulus lupulus L.). Because use of plant tissue cultures is associated with occurrence of somaclonal variability, we assessed somaclonal variability in hop meristem in vitro cultures before and after thermotherapy by different molecular methods (RFLP, RAPD, STS, ISSR and AFLP) and compared it with existing clonal variability of Osvald's clones 31, 72 and 114. No molecular differences were observed between mother plants and in vitro mericlones by RFLP and STS analyses. Amplified molecular differences were found in RAPD and ISSR products of one from five in vitromericlones cvs. Eroica (E5) and Southern Brewer (SB2), respectively. Similarities with mother plants were 0.965 and 0.913 (JSC), respectively. Specific amplified polymorphic products were found for every mericlone and mother plant in AFLP reactions and variability of DNA sequence ranged from 0.824 to 0.993 (JSC). This variability was very similar to determined intra-clonal variability within Osvald's clones 31, 72 and 114 by AFLP analysis. Inter-clonal variability of DNA sequence was exactly higher than intra-clonal variability of DNA sequence in these clones. The molecular differences between Osvald's clone 72 normal and meristem derived were not verifiable. Thermotherapy increased frequency of molecular changes, since amplified differences were found in 14 from 20 in vitro mericlones of cv. Eroica, in 6 from 11 in vitro mericlones of cv. Yeoman and in 15 from 23 in vitro mericlones of cv. Southern Brewer by RAPD and ISSR analyses.     

Cattle stunning with a penetrative captive bolt device: A review

The captive bolt device has been used for stunning cattle at abattoirs for more than 100 years and is now one of the stunning devices used most widely. The aim of this review article was to assess the effects that are decisive during cattle slaughter on the quality of stunning with the use of a captive bolt stunning device. The basis of effective stunning is the use of a suitable type of device, with the speed of the bolt and the kinetic energy corresponding to the anatomical parameters of the slaughtered animal. The importance of the regular cleaning and maintenance of stunning devices and monitoring of the effectiveness of stunning goes without saying. The immediate loss of sensibility in the animal must occur after the first shot. The effectiveness of the stunning process can be quantified by regular monitoring of the behavior of animals after stunning with an emphasis on the loss of reflexes (corneal reflex, regular breathing, attempts to regain physiological posture) and checks on the shot location on the skulls of slaughtered animals.     

The interaction of folpet with the glutathione-dependent demethylation enzyme system of rat liver

The interaction of folpet with the glutathione-dependent enzyme demethylation of fenitrothion was studied. In a reaction catalyzed by methyltransferase from rat liver in the presence of 0.3 μmol of glutathione, 0.21 μmol of folpet caused a 100% inhibition of the demethylation of 0.2 μmol of fenitrothion. A parallel study was made on the qualitative and quantitative course of the reaction between folpet and glutathione. Phthalimide was formed as the main degradation product of folpet, but the composition of the degradation products of glutathione was dependent on the molar ratio of the reactants. Compounds absorbing at 267 nm (probably derivatives of 2-thiazolidinethiones) were formed when the ratio of glutathione to folpet was 4.5:1. When this ratio was reversed, oxidized glutathione was the main product. From observations on the course of the enzymatic demethylation of fenitrothion and on the degradation of folpet by glutathione, it appears that in the enzyme demethylation system, the reaction between fungicide and glutathione predominates.     

Epidemiological enquiries in two Q fever outbreaks in a community of Baden-Württemberg during 2008 and 2009

In 2008 and 2009, two consecutive outbreaks of Q fever in humans were recorded in the district of Freudenstadt, northern Black Forrest, Baden-Württemberg, Germany. In 2008, a total of 41 persons from a single local community fell ill and were found infected with Coxiella burnetii. Although comprehensive diagnostic and epidemiological outbreak investigations were conducted and control measures taken which included vaccination of ruminants at risk in three parts of the affected community, re-occurrence of the disease in 2009 with further 29 confirmed human Q fever cases could not be prevented. While the origin of infection of the first outbreak was probably a flock of 550 sheep moved in the surrounding of the affected villages, the source of infection for the consecutive outbreak in 2009 could not be identified. It seems possible that meadows contaminated with infectious placenta or birth fluids represented the sources of infection.