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During the 20th century, there has been an ongoing agricultural expansion and global warming, two of the main determinants influencing biodiversity changes in Argentina. The red hocicudo mouse (Oxymycterus rufus) inhabits subtropical grasslands and riparian habitats and has increased its abundance in recent years in central Argentina agroecosystems. This paper describes the long‐term temporal changes in O. rufus abundance in Exaltación de la Cruz department, Buenos Aires province, Argentina, in relation to weather fluctuations and landscape features, as well as analyzes the spatio‐temporal structure of captures of animals. We used generalized liner models, semivariograms, the Mantel test, and autocorrelation functions for the analysis of rodent data obtained from trappings conducted between 1984 and 2014. O. rufus showed an increase in abundance across the years of study, with its distribution depending on landscape features, such as habitat types and the distance to floodplains. Capture rates showed a spatio‐temporal aggregation, suggesting expansion from previously occupied sites. O. rufus was more abundant at lower minimum temperatures in summer, higher precipitation in spring and summer, and lower precipitations in winter. Weather conditions affected O. rufus abundance, but there was local variation that differed from global patterns of climate change. [ABSTRACT FROM AUTHOR]

Rachiplusia nu (Guenée) (Lepidoptera: Noctuidae, Plusiinae) is a defoliator of soybean (Glycine max L., Fabaceae), sunflower (Helianthus annuus L., Asteraceae), alfalfa (Medicago sativa L., Fabaceae), and horticultural crops in temperate southern South America; however, there is little genetic information available about this pest insect. Recently, concerns about this insect have increased because of its suspected resistance to Bt soybean and its spread to tropical regions. To better understand pest dynamics, and therefore implement suitable management strategies, a thorough knowledge of the genetic variability and spatial structuring of populations is required. In this paper, R. nu larvae were sampled from various crops and locations in central Argentina (where the pest is endemic) to assess diversity and population structure through mtDNA sequence analysis. In addition to the analysis of the standard cytochrome c oxidase subunit I (COI) 'barcode' fragment, a new set of primers was developed to explore genetic variation in the cytochrome b (Cytb) gene. COI and Cytb concatenated sequences revealed an overall high haplotype diversity (mean ± SD = 0.798 ± 0.037) and low nucleotide diversity (0.00137 ± 0.00013). The haplotype network showed a total of 19 haplotypes, separated by at most five mutational steps. A main central haplotype and four additional frequent haplotypes (accounting for 80% of the specimens examined) were distributed across populations with no obvious pattern related to host plant or geographic origin. Analysis of molecular variance further supported a weak population structure, where genetic variation within populations was the main source of total variation (ca. 96%). Pairwise comparisons showed only minor genetic differentiation among some of the populations studied. Implications of these findings in the context of R. nu control are discussed. [ABSTRACT FROM AUTHOR]

Triatominae, commonly known as kissing bugs, are a group of approximately 150 species of hematophagous reduviids, some of which are vectors of Trypanosoma cruzi, the etiological agent of the Chagas disease. Distributional patterns of triatomines have been studied based on macroecological and historical biogeographic approaches, but the definition of distributional patterns and areas of endemism are yet to be defined based on objective criteria. We used two methods to identify biogeographic units in the Triatominae: the endemicity analysis based on an optimality criterion (NDM/VNDM software) and a network approach aimed to simplify and highlight the underlying structure in species distributions (Infomap Bioregions). Information on species distributions was obtained from a data paper, comprising 21 815 records for 135 triatomine species occurring in the Americas. The resulting areas of each method were clustered using a meta consensus criterion based on dissimilarities and interpreted as recurrent areas. The NDM areas show a nested structure, presenting greater restrictions to the inclusion of species in a given area, requiring broad sympatry. In contrast, bioregions emphasize spatial patterns with better‐delimited areas and species occurrences do not need to be highly congruent. When areas were clustered based on their species composition two clear patterns arose from both methods: (i) areas within the southern Amazon and southeast South America, especially in the Chacoan subregion, formed a cluster, and (ii) areas north of the Amazon, Pacific, Mesoamerica, Mexican transition zone and Nearctic formed another cluster. Moreover, within each of these two clusters, there was a latitudinal gradient of the areas in the Americas showing spatial similarity between the areas found in both methods. Results of both methods show well‐bound areas separating the triatomine fauna in the Brazilian subregions, resulting in the recognition of areas corresponding to the biomes Chaco, Pampa, Cerrado, and Caatinga, and, to a lesser extent, the Atlantic Forest. [ABSTRACT FROM AUTHOR]

This paper presents the first petrographic study of pottery made by hunter–gatherer societies that inhabited the eastern Pampa–Patagonia transition regions (Buenos Aires province, Argentina), between c.1900 and 400 radiocarbon‐years bp. The data show that the potters maintained technical choices during this period as part of a technological tradition. With this common knowledge, local fabric recipes coexisted linked to the regularity of the use of raw materials in accordance with the geology of the research area. Furthermore, the finding of archaeological clay doughs would indicate the in situ production of vessels in the residential contexts of these pre‐Hispanic populations. [ABSTRACT FROM AUTHOR]

This paper investigates species richness and species occupancy frequency distributions (SOFD) as well as patterns of abundance–occupancy relationship (SAOR) in Odonata (dragonflies and damselflies) in a subtropical area. A total of 82 species and 1983 individuals were noted from 73 permanent and temporal water bodies (lakes and ponds) in the Pampa biome in southern Brazil. Odonate species occupancy ranged from 1 to 54. There were few widely distributed generalist species and several specialist species with a restricted distribution. About 70% of the species occurred in <10% of the water bodies, yielding a surprisingly high number of rare species, often making up the majority of the communities. No difference in species richness was found between temporal and permanent water bodies. Both temporal and permanent water bodies had odonate assemblages that fitted best with the unimodal satellite SOFD pattern. It seems that unimodal satellite SOFD pattern frequently occurred in the aquatic habitats. The SAOR pattern was positive and did not differ between permanent and temporal water bodies. Our results are consistent with a niche‐based model rather than a metapopulation dynamic model. [ABSTRACT FROM AUTHOR]

The Pampa comprises the most productive land in Argentina, but the widespread adoption of sole cropping has drastically reduced soil organic carbon (SOC) stocks. This paper presents baseline data on the effects of maize-legume inter-crops compared with maize and soyabean sole crops on SOC and nitrogen (N) stocks, gross SOC turnover, soil microbial biomass (SMB), soil organic matter light fraction (LF) and the partitioning of carbon (C) derived from C- and C crops into SOC, LF and SMB. For soil characteristics, only the C:N ratio was significantly different (0-120 cm) between treatments. Gross SOC and SMB-C turnover time (0-120 cm) was faster in the maize sole crop followed by the inter-crops and the soyabean sole crop. The SMB-C and N were significantly greater in the intercrops. Soil LF-N (0-20 cm) was significantly smaller in the inter-crop. Soil became significantly enriched (0-120 cm) in δN in the inter-crop, suggesting that microbial decomposers incorporated C derived from maize and soyabean residues. The greatest proportion of C in the soil and in the soil LF was derived from a C-C source, and the δC of the SMB (0-20 cm) was enriched compared with that of the SOC and the soil LF. Results from this study indicated that after only 1 year of inter-cropping, soil biological and chemical characteristics were influenced positively by this land management practice. [ABSTRACT FROM AUTHOR]

This paper analyses the soya bean yield variability in the Argentine Pampas in relation to the atmospheric circulation patterns in southern South America. The region studied is the main soya bean production area in Argentina and contributes a high percentage to world trade in soya beans and their byproducts.Two datasets were used: the soya bean yield series of 58 provincial districts and daily average fields of 1000 and 500 hPa geopotential height corresponding to the NCEPReanalysis 2 in the period 1979–2001. Adverse impacts on final yield may be mainly associated to weather types WTs related to intense rainfall during harvest time April and May and to structures which favour stability and warm advection in the summer at lower levels. The thermal effect on soya bean may be observed in the WTs whose configuration of anomalies favours the incursion of cold air at the lower levels contributing to low temperatures during seed germination and early vegetative growth stages. Positive impacts may be associated with WTs that reduce thermal stress during flowering and pod set stages summer and WTs which favour stability at harvest time April.In general terms, atmospheric circulation structures have been identified as elements which may be added to the set of climate predictors to explain a part of interannual yield variability. The structures found have direct implications for short and middle term forecasts. They constitute a primary element for the monitoring of the growing season of the soya bean crop and for planning strategies. Copyright © 2009 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Well-developed Bt horizons of five palaeosols (P1–P5) have been recorded previously within a 20-m-thick succession of Pliocene siltstones and clayey siltstones in the southern part of the Buenos Aires Province of Argentina. This paper reports a detailed field and micromorphological (thin section) investigation of a 6-m portion of the sequence encompassing P2 and P3. Large-scale faunal burrow infillings occur throughout: other bioturbation features in the form of channel and spongy microstructures are mainly confined to the siltstones. The intervening clayey siltstones (Bt horizons) have been affected more by shrink–swell disruption, as evidenced by slickensides and a range of striated b-fabrics in thin sections. Clay coatings, indicative of illuvial accumulation of clay translocated in suspension from overlying A or E horizons, occur in both the siltstones and clayey siltstones. The types, microstratigraphic associations and depth functions of features are interpreted in terms of changing interactions, balances and dominances between sedimentary, pedogenic and erosional processes over time, thus providing the basis for the pedosedimentary reconstruction of landscape evolution in the region during part of the Pliocene represented by the whole P1–P5 sequence (4–5 Ma BP). It is envisaged that this period was dominated by aeolian deposition, although fluvial and mass movement processes probably led to reworking and redistribution of some of the materials. Overall rates of subaerial deposition, however, were not substantial: pedogenic processes were active throughout, the balance between sedimentation and pedogenesis varying over time in a cyclical fashion. Phases of reduced deposition and establishment of relatively stable land surfaces were marked by the development of argillic soil profiles with clearly defined eluvial and illuvial horizons. Intervening periods of more rapid accumulation of coarser material were characterized by accretionary soil development and welding of new pedological features on existing soils as the surface accreted, first transforming existing eluvial horizons into BCt/AE horizons (siltstones) and then encouraging the syndepositional upward extension of these complex horizons. The primary basis of the alternating units of siltstones (BCt/AE horizons) and clayey siltstones (Bt horizons) lies in the cyclical change in size of particles deposited, although pedogenic translocation processes enhanced these textural differences. The underlying driving mechanism behind the pedosedimentary cycle can only be speculated upon, although it is tempting to relate the sedimentation pattern to climatic fluctuations linked to glacial advances and retreats in the Patagonian Andes during the Pliocene. [ABSTRACT FROM AUTHOR]