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[en] There is a growing interest for the application of biomakers to field-collected earthworms. Therefore we have evaluated the usability of native populations of endogeic, widely distributed earthworm Aporrectodea caliginosa in the assessment of soil genotoxicity using the Comet assay. Validation of the Comet assay on earthworm coelomocytes has been established using commercially available Eisenia fetida exposed to copper, cadmium, and pentachlorophenol, along with A. caliginosa exposed to copper in a filter paper contact test. Neutral red retention time (NRRT) assay was conducted on copper exposed and field-collected earthworms. Significant DNA and lysosomal damage was measured using Comet and NRRT assays in native populations of A. caliginosa sampled from the polluted soils in the urban area in comparison to the earthworms from the reference site. The results of this study confirm the employment of A. caliginosa as a suitable species for the in situ soil toxicity and genotoxicity field surveys. - Research highlights: → Native A. caliginosa has shown significant biological effect measured by the Comet and NRRT assays. → The Comet assay on A. caliginosa and E. fetida has shown to be of similar sensitivity as the NRRT assay. → A. caliginosa is a suitable species for the in situ soil toxicity and genotoxicity field surveys. - Native populations of endogeic earthworm Aporrectodea caliginosa can be successfully applied in the genotoxicity field surveys using Comet assay.
[en] Fluctuations in population dynamics, like demographic expansions and invasions, are relatively common in ecosystems, and in certain cases may affect biodiversity and a suite of other ecological attributes. In this paper, we report the appearance and population explosion of the reef-building polychaete (Sabellariidae) Idanthyrsus cf. cretus in Gorgona Island (Eastern Tropical Pacific), describing some ecological characteristics (abundance and coverage). The survey was carried out in three study areas of Gorgona Island, located in the Colombian Pacific. Sampling was performed randomly at low, mid and high intertidal levels, in order to measure density and coverage. Density was measured randomly in three study areas at low, mid and high intertidal levels collecting samples (N=37) of 100 cm2 from the colony. Coverage was measured using random transects (N=21) per locality and intertidal levels (20 m length per 1 m width). A total of 1,904 I. cf. cretus were collected with a mean density of 73 ind./100 cm2. Coverage was statistically different between intertidal zones, with the highest values in the mid-intertidal level (11%). Differences in coverage of I. cf. cretus colonies among study areas are probably due to differing intertidal physical characteristics: the availability of adequate substrate and building materials in the study areas sediments, which in turn might affect abundance and colony size. Suitable substrate and construction material might have favored the rapid spreading and local invasion of this species.
[en] Recently, studies looking at the small scale interactions taking place in complex networks have started to unveil the wealth of interactions that occur between groups of nodes. Such findings make the claim for a new systematic methodology to quantify, at node level, how dynamics are influenced (or differentiated) by the structure of the underlying system. Here we define a new measure that, based on the dynamical characteristics obtained for a large set of initial conditions, compares the dynamical behavior of the nodes present in the system. Through this measure, we find that the geographic and Barabási–Albert models have a high capacity for generating networks that exhibit groups of nodes with distinct dynamics compared to the rest of the network. The application of our methodology is illustrated with respect to two real systems. In the first we use the neuronal network of the nematode Caenorhabditis elegans to show that the interneurons of the ventral cord of the nematode present a very large dynamical differentiation when compared to the rest of the network. The second application concerns the SIS epidemic model on an airport network, where we quantify how different the distribution of infection times of high and low degree nodes can be, when compared to the expected value for the network. (paper)
[en] The ocean has been assumed as the main sink of microplastics (MPs), however, soils may also receive MPs from different sources and through different pathways, which may affect the biota and their role in soil functions. To the best of our knowledge, only one study, until now, reported the effects of MPs on the survival and fitness of soil organisms (Lumbricus terrestris). In our study, epigeic earthworms, of the species E. andrei, were exposed to different concentrations of MPs (0, 62.5, 125, 250, 500 and 1000 mg/kg soildw) in an OECD artificial soil and tested for reproduction, survival and growth of adults, following a standard protocol. The size of the polyethylene MPs to which earthworms were exposed ranged between 250 and 1000 μm. No significant effects were recorded on survival, number of juveniles and, in the final weight of adult earthworms after 28d of exposure, to the different concentrations of MPs. Nevertheless, FTIR-ATR of earthworms and histopathological analysis of the gut provided evidences of damages and immune system responses to MPs. - Highlights: • Earthworms may be able to selectively ingest microplastics and/or to egest them. • Serious histological damages in the gut of earthworms were observed. • Molecular changes in the body of earthworms point for possible immune system responses. • Hystopathopatological analyses also showed serious signs of gut inflammation. • Immune system responses seemed to be related with those to deal with strange bodies. - This is one of the first studies assessing the effects of microplastics on terrestrial earthworms and it provides evidence of tissue damage in the gut and immune system responses.
[en] A great many living beings, such as aquatics and arthropods, are equipped with highly sensitive flow sensors to help them survive in challenging environments. These sensors are excellent sources of inspiration for developing application-driven artificial flow sensors with high sensitivity and performance. This paper reviews the bio-inspirations on flow sensing in nature and the bio-mimicking efforts to emulate such sensing mechanisms in recent years. The natural flow sensing systems in aquatics and arthropods are reviewed to highlight inspirations at multiple levels such as morphology, sensing mechanism and information processing. Biomimetic hair flow sensors based on different sensing mechanisms and fabrication technologies are also reviewed to capture the recent accomplishments and to point out areas where further progress is necessary. Biomimetic flow sensors are still in their early stages. Further efforts are required to unveil the sensing mechanisms in the natural biological systems and to achieve multi-level bio-mimicking of the natural system to develop their artificial counterparts. (topical review)
[en] Little research has been performed on the impact of pesticides on earthworms under tropical conditions. Taking into consideration the often-limited resources in tropical countries, simple screening tests are needed. Therefore, it was investigated whether three pesticides relevant for the Brazilian Amazon (benomyl, carbendazim, lambda-cyhalothrin) affect the avoidance behavior of the earthworm Eisenia fetida. The tests were performed for two days according to ISO guideline 17512 but were adapted to tropical conditions (i.e. test substrate, test organism and temperature). The results indicate that this test gives reproducible and reliable results. Toxicity values (NOEC, EC50) are lower than those determined in 14 day-acute mortality tests and are approximately in the same range such as those found in 56 day-chronic reproduction tests with the same earthworm species, which were performed in parallel. Therefore, the use of the earthworm avoidance tests is recommended as a screening tool for the risk assessment of pesticides. - The earthworm avoidance test is a practical and sensitive screening method for assessing the effects of pesticides in tropical soils
[en] Previous work has identified two patterns of arthropod recovery after insecticide applications to arable crops: dispersal-mediated recolonisation from untreated areas (Type A) and recolonisation within treated areas assisted by reduced predation (Type B). In this study, connectivity between field-edge habitats was manipulated using barriers to investigate whether a crop edge and adjacent hedgerow influence recolonisation of an insecticide-treated crop by surface-active Collembola and other arthropods. Collembola recovery patterns differed among closely-related taxa. Epigeic collembolan and macroarthropod communities were more diverse and abundant, and rates of artificial prey predation were higher, in sprayed crop areas connected to both hedgerow and unsprayed crop edge than in sprayed areas connected to the unsprayed edge alone. These findings indicate that effectiveness of unsprayed crop edges as sources of field recolonisation may depend on adjoining field margin habitats. An assumption in risk assessment that unsprayed crop edges assist population recovery within treated areas is not supported. - Collembola recolonisation differs among species; effectiveness of unsprayed crop edges as sources of arthropod recolonisation may depend on adjacent habitat
[en] Sexual dimorphism is obvious in Papilio memnon. The female adult resembles that of Papilio polytes another citrus butterfly species. However, marked difference is observed in the size and red spots on the base of the forewing. The adult male P. memnon is blue black in colour and red spots are present on the base of the underside of both for and hind wings. The win span of sexes ranges from 120mm to 150mm. The breeding season is from end of June to early part of January, the peak being in the month of November. The recorded diagnostic external features of this studied species are described supported by scaled photographs. Seasonal abundance of this species is also mentioned. It is learnt through the internet that a mounted specimen of this species fetched $2.95 in Malaysia. It is therefore concluded that successful rearing of this species in captivity could be of benefit to the country.