Abstract:

El arroz expandido se utiliza en la fabricación de galletas para el consumo humano. Esta industria genera una gran cantidad de desperdicios biodegradables, principalmente un scrap con predominio de hidratos de carbono. Este desperdicio eleva la relación carbono/nitrógeno de la materia orgánica biodegradable con déficit de carbono. En el caso de las “camas” de pollos parrilleros (estiércol más cáscara de girasol, relación C/N= 14.6), el empleo de scrap optimiza su compostaje a una relación C/N= 40/1 – 30/1. En experiencias realizadas en el campo, con muestreos bimensuales, y en cultivos de Eisenia fetida con manejo mediante autosiembra (adición a las “camas” de pollo de 8-16% de scrap), resultó una buena aceptación del sustrato. Respecto del testigo (“cama” de pollos parrilleros), el incremento de la población de E. fetida al cabo de 127 días no se diferenció significativamente, al igual que en la producción de cocones. En laboratorio se realizaron cultivos con tres tipos de dieta para E. fetida con un control semanal del peso y con tres réplicas por dieta. La dieta 1 (testigo) se hizo en base a estiércol de conejo, la dieta 2 con compost de residuos domiciliarios y la 3 con scrap puro como medio-alimento de las lombrices. En los cultivos con scrap, con respecto a los otros dos, se observó que en 12 semanas presentaron más animales sexualmente maduros (dieta 1 = 16.7%; dieta 2 = 26.7%; dieta 3 = 91.3%). Independientemente de la dieta, las lombrices adquirieron la madurez con pesos corporales mayores a 0.24 g. Presentaron mayor producción de cocones/animal (dieta 1 = 0.37; dieta 2 = 0.86; dieta 3 = 1.65) acorde con la elevación del potencial reproductor (dieta 1 = 2330; dieta 2 = 3729; dieta 3 = 12772). El peso medio en 17 semanas superó al de las restantes dietas en un 47% (dieta 1 = 0.178 g, DS = 0.0751, n = 27; Dieta 2 = 0.265 g, DS = 0.0738, n = 30; dieta 3 = 0.567 g, DS = 0.1276, n = 23).

Industrial puffed rice scrap increases the carbon/nitrogen ratio in carbon-poor biodegradable organic matter, such as broiler chicken beddings (C/N= 14.6) (droppings + sunflower husks), optimizing the composting process. In Eisenia fetida field experiences (bimonthly sampling) done on cultures managed through self-inoculation (addition of 8-16% scrap to the chicken bedding), the substrate was accepted. Population increase and cocoon production, measured 127 days after the start, were not significantly different from control plots (broiler chicken bedding). Population size expanded with a nominal (nd) and effective (ed) increase of 2.69 and 3.51 times respectively compared to the initial numbers. The carrying capacity of the different organic matter mixtures approximates 30000 worms/bed (2m²) (w/B). The reproductive potential (“R”) showed fluctuations (between 1000 and 10800 w/B) which agree with the dynamics of a population under this management strategy. Humus production was approximately 35 tons from an original 63.9 tons. In laboratory cultures (weekly weight control) with pure scrap, as worm substratum-feed, the following results, compared to home waste compost and rabbit manure (control), were recorded: more sexually mature animals; higher cocoon-per-animal production; average weight (at 17 weeks) a 47% higher than the weight obtained when using other diets.

Abstract:

Sinotaia quadrata is a snail native from Asia recorded for the first time in South America in 2009 in centralArgentina. In 2015, this species was also found in a lowland stream with different water qualities. Our aimswere to contribute to the knowledge of its population ecology and to compare the individuals from the twolocations anatomically. Snails were searched at 6 sites, where physicochemical and hydraulic parameters were measured. Biological samples were also taken at two sites (S3 and S4) to study the population traits of S. cf quadrata (density, sizestructure, fecundity and sex ratio) and to assess the water quality throughmacroinvertebrates’ biological indices (richness, diversity and IBPamp). Physicochemical and biologicalparameters allowed us classifying sites as “moderately polluted” (S3) and “heavily polluted” (S4). At S4,the population showed a lower density, larger individuals, higher fecundity and a scarce representation ofyoung snails. The differences observed in the radula and mantle border of snails from the two geographicalregions might be attributed to environmental differences. We conclude that this species is tolerant to a widerange of environmental variables which, along with its high fecundity and morphological plasticity, couldallow this species to colonize neighbor streams.

Abstract:

In this work is reported the first record of Melanoides tuberculatus in the Iguazú River basin (Argentina-Brazil). This species is native to southern Asia and was anthropogenically introduced to America in the 1960s decade. Sixteen specimens (one adult and 15 juvenile) of M. tuberculatus were recorded at only one site, the rapids of Iguazú River at Isla San Martín, Iguazú National Park, Argentina, in June 2005. This finding of M. tuberculatus specimens suggests the presence of a stable population that would represent a threat to the native mollusk fauna, given that this species promotes replacement and impoverishment of mollusk diversity.

En este trabajo se reporta el primer registro de Melanoides tuberculatus en la cuenca del río Iguazú (Argentina-Brasil). Esta especie es nativa del sudeste asiático y fue introducida por el hombre en el continente americano en la década de 1960. Dieciséis ejemplares (un adulto y 15 juveniles) de M. tuberculatus fueron colectados en junio de 2005 en un solo sitio del Parque Nacional Iguazú (Argentina), correspondiente a los rápidos de la Isla San Martín. Este hallazgo sugiere la presencia de una población estable que podría representar una amenaza a la fauna de moluscos nativa, dado que esta especie provoca un reemplazo y empobrecimiento de la diversidad de moluscos.

Abstract:

Author affiliation: Gutiérrez Gregoric, Diego Eduardo. División Zoología Invertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentina

Author affiliation: Núñez, María Verónica. División Zoología Invertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentina

Author affiliation: Vogler, Roberto Eugenio. División Zoología Invertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentina

Author affiliation: Beltramino, Ariel Aníbal. División Zoología Invertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentina

Author affiliation: Rumi, Alejandra. División Zoología Invertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentina

Abstract:

We scored the presence of Digenea larvae in the gonadal follicles and digestive glands of males and females of a <em>Heleobia parchappii</em> (d’Orbigny, 1835) (Mollusca, Cochliopidae) population living in an artificial lake located adjacent to an anthropically impacted area, region of Tigre in the Province of Buenos Aires, Argentina; making seven samplings from May 2005 through May 2006. In the laboratory, we separated subsamples for both histology and parasite-emergence assessment. The former examined the gonadal-development stages in relation to larval presence along with the effect of the larvae on the gonadal tissue and calculated parasite prevalence per age and size. Larval prevalence increased with host length and was greater in post-reproductive-stage individuals, with those >7.5 mm long reaching 100% parasitization. That stage became maximal in August, while juveniles predominated in December and January. The females were predominant almost throughout the year, but were parasitized at the same frequency as the males (p=0.38). This year-round <em>H. parchappii</em> parasitization indicates that Digenea can complete their life cycle in an anthropically impacted environment, thus affecting the autochthonous fauna, pets, and even humans. Mollusk parasitization by Digenea larvae is used to evaluate anthropic environmental pressure as an indicator of pollution by wastes, chemicals, or other refuse resulting from the human presence. The study site exemplifies the recent spate of urban construction projects characterized by housing developments around modified water bodies. Keywords. Cochliopidae, digenea larvae, histology, Buenos Aires, Argentina

Artículo enviado a "Molluscan Research" a la espera de aprobación para su publicación.

Abstract:

The Island of Martin Garcia is located in the Upper Río de la Plata, to the south of mouth the Uruguay River. The aim of the present study was to analyse the biodiversity of the island freshwater mollusks and their relationships to environmental variables. Twelve sampling sites were selected, five were along the littoral section of the island and seven were Inland ponds. Seven major environmental variables were measured: water and air temperature, percentage of oxygen saturation, dissolved oxygen, electrical conductivity, total dissolved solids and pH. Twenty-seven mollusk species were found, Antillorbis nordestensis, Biomphalaria tenagophila tenagophila, B. t. guaibensis, B. straminea, B. peregrina, Drepanotrema kermatoides, D. cimex, D. depressissimum, Chilina fluminea, C. rushii, C. megastoma, Uncancylus concentricus, Hebetancylus moricandi, Stenophysa marmorata, Heleobia piscium, H. parchappii, Potamolithus agapetus, P. buschii, P. lapidum, Pomacea canaliculata, P. megastoma Asolene platae, Corbicula fluminea, Eupera platensis, Pisidium sterkianum, P. taraguyense and Limnoperna fortunei. UPGMA clustering of species based on their occurrence in different ecological conditions revealed two main species groups. The Canonical Correspondence Analysis suggests that the species distribution is related to the physico-chemical condition of water. Axis two of the ordination diagram displayed the approximately 95.6% of the correlation between species and environmental variables. Dissolved oxygen, conductivity, water temperature and pH showed the highest fluctuations during the sampling period. The species richness (S) showed relationships mainly with water temperature and conductivity. The biodiversity of the gastropods and bivalves from Martín García Island amounts to up to 26 species. Among the Gastropoda, the Planorbidae family made the most sizeable contribution. The Lithogliphidae P. agapetus (26.28%) and P. buschii (9.50%) showed the highest relative frequencies of occurrence within the littoral environments, while the Planorbidae D. cimex (23.83%) and D. kermatoides (11.59%) likewise did so in the inland ponds.

Abstract:

Author affiliation: Rumi, Alejandra. División Zoología Invertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentina

Author affiliation: Vogler, Roberto Eugenio. Departamento de Biología. Facultad de Ciencias Exactas, Químicas y Naturales. Universidad Nacional de Misiones. Posadas; Argentina

Abstract:

Author affiliation: Gutiérrez Gregoric, Diego Eduardo. División Zoología Invertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentina

Author affiliation: Núñez, María Verónica. División Zoología Invertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentina

Author affiliation: Rumi, Alejandra. División Zoología Invertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentina

Abstract:

The exotic land gastropod Ovachlamys fulgens (Gude, 1900), aka the jumping snail, was registered in Eldorado city, Misiones province, constituting the first documented record of that species in Argentina– and for all of South America as well. Identities of the individuals were confirmed through morphological examination, and by a DNA sequencing of the cytochrome oxidase subunit I gene. DNA sequences for the mitochondrial 16S-rRNA and the nuclear 18S-rRNA genes were also obtained from the morphologicallyconfirmed specimens to gain insights into the genetic background of this species in Argentina, and as additional markers for enhancing the rapidity of identification by governmental authorities who are responsible for managing the presence of exotic species. Different size classes suggested that the species had successfully reproduced and become established in the locality. Ovachlamys fulgens is emphasized in the literature as being a serious pest to orchids. Misiones province harbors a high species richness of orchids, representing about one half of the known species in Argentina. Owing to the use of the orchid as an ornamental plant, the commercial trade could have facilitated the introduction of the species into Argentina. Control measures, preventive education, and surveillance are needed to prevent the further spread of this snail.