Analysis of the management of grasshopper species (Orthoptera: Acrididae), agricultural pest in Laprida county, Buenos Aires, Argentina

Grasshoppers are among the dominant insects in most grassland systems. These insects’ communities tend to exhibit temporal variations in the distribution and abundance of their species, and during outbreak years cause important economic loss in both implanted pastures and crops. In the study area, Laprida county, as well as in other areas of Buenos Aires province, this pest problem has been recognized since last century. The aim of this study was to analyze the pest management of grasshoppers made by farmers and related institutions in Laprida using both qualitative (interviews and documentary observation) and quantitative methods (surveys). About 80% of surveyed farmers considered that grasshoppers are the main pest in the region, and 60% of them apply chemical insecticides against this pest, mainly on crops. Besides, only 12.8% of surveyed farmers are aware of nonchemical alternatives for pest control, such us biological control and natural enemies. Most of the interviewed farmers acknowledged the importance of preventive management through systematic grasshopper monitoring and spot treatments in risky areas. Additionally, farmers showed interest in the implementation of more environmentally-safer strategies such as biological control.

Insect Marks on Bones from La Guillerma Archaeological Locality (Salado River Depression, Buenos Aires, Argentina)

The La Guillerma archaeological locality is located in the northeast sector of Buenos Aires province (Argentina). Two of its sites (LG1 and LG5), dated between ca. 1400- and 600-years BP, have a great amount of faunal remains including deer, rodents, fish and small birds that are subjected to taphonomic agents and processes (e.g., weathering, manganese, roots). Previous studies have shown osteophagic behaviour in different insects (e.g., Coleoptera, Blattodea). In this paper, we evaluate their incidence on La Guillerma faunal assemblage. We performed an analysis on marks that were identified in bone remains of various taxa and applied the criteria for identifying bone alteration by insects (i.e., by measuring each trace and comparing them with the types of insect marks described in the literature). Fifteen specimens (LG1 = 6 and LG5 = 9) exhibited different types of modifications (e.g., pits with striae in base, pits with emanating striae, striations) that are related to the action of insects. Although the proportion of affected bones is low in relation to the total sample, we highlight our study as the first detailed analysis of insect marks on archaeological bones from Argentina. We also emphasize the significance of addressing insect-produced modifications on Argentinean archaeological sites.

Quaternary Marine Mollusk Associations of the Last Interglacials in North Patagonia (Argentina): Paleoecology and Paleoclimates

Deposits of different Quaternary marine transgressions are largely exposed in the Argentine north Patagonian littoral (39°15′S–41°02′S), south of the Buenos Aires and north of Río Negro provinces. The malacological associations of 84 sites were studied. Among them, 31 belong to Pleistocene deposits of the interglacials ≥ MIS 9, MIS 7, MIS 5e, 29 to Holocene deposits of the interglacial MIS 1, and 24 sites of modern beaches. These sites yielded 7385 fossils among valves and shells, of 78 species (42 bivalves and 36 gastropods), including 11 micromolluskan species. The record of the bivalves Crassostrea rhizophorae in the south of the Buenos Aires Province, and Anomalocardia brasiliana (both currently inhabiting lower latitudes), and very likely the gastropod Tegula atra (inhabiting today the Pacific Ocean) in the north of Río Negro Province, suggests that interglacials MIS 7, MIS 5e and MIS 1 were warmer than today. However, the associations determined for the studied interglacials have not changed in their composition, but in abundance of species, except for the latitudinal shifts of the three mentioned species, and the presence of cold to temperate water taxa since the MIS 1 in the ecotonal area of the north of Río Negro Province. Changes in the associations of northern Patagonia during the Quaternary derived from global changes (sea surface temperature, salinity, etc.), and the existence of habitat heterogeneity in each of the areas, that enabled the co-existence of different bivalve and gastropod species of the local benthic marine malacofauna.

Fragmentation of Coastal Grasslands by Plantations and Spontaneous Spread of Invasive Pines in the Southern Pampa

Coastal dunes of the southern Buenos Aires province, in Argentina, are one of the last remnants of biodiversity in the southern Pampa unit, within the Rio de la Plata Grasslands. While the direct loss of grasslands due to the advance of cities and afforestation is conspicuous, the negative effects of the subdivision of the remaining environments on biodiversity and ecosystem dynamics are less considered. Our work aimed to analyze the combined effect of fires and subdivision of grasslands by invasive alien trees. Our results suggest that fragmentation affects the resilience of coastal grasslands after fire and affects the course of succession, promoting the establishment of invasive alien plants. We also suggest that fires favor the advance of pines and acacias towards the interior of grassland remnants, further reducing their area. The effective conservation of the components of Pampas biodiversity that still persist in these coastal ecosystems will depend on preventing, mitigating and compensating the insularization effects associated with forest plantations and the expansion of invasive trees, by means of adequate territorial planning that allows remnants to be maintained in a good state of conservation.

Dense Bathymetry in Turbid Coastal Zones Using Airborne Hyperspectral Images

We used airborne hyperspectral images to generate a dense survey of bathymetric data in the Bahía Blanca estuary (Buenos Aires Province, Argentina). This estuarine area is characterized by intense sediment transport turning the water muddy, and thus optical bathymetric estimations are difficult. We used 24 spectral bands in a range of 500–900 nm acquired with a hyperspectral camera aboard an unmanned aerial vehicle, together with 100 bathymetry data points surveyed with a sonar sensor aboard an unmanned surface vehicle, covering an area of about 800 m2. Random-forest and support-vector-machine regressors were trained with this data set. The resulting model yielded a determination coefficient of 0.815 with unseen data, a root-mean-square error of 0.166 m, and an absolute average error less than 2%. These results allow dense and accurate reconstructions of the underwater profile in wide, muddy, shallow regions of the Bahía Blanca estuary, showing the feasibility of hyperspectral imagery combined with sonar data in turbid shallow waters.

Sources of phenotypic variation of wood density and relationships with mean growth in two Eucalyptus species in Argentina

Aims of the study: To describe the radial patterns of wood density, and to identify their main sources of variation, and the potential tradeoffs with mean tree growth, in two Eucalyptus species. Area of study: Mesopotamian (Corrientes and Entre Ríos provinces) and Pampean region (Buenos Aires province) of Argentina. Materials and methods: Eucalyptus grandis and Eucalyptus viminalis, growing in genetic trials installed in two sites per species were studied. X-ray wood microdensity profiles were developed from core samples. Each profile was proportionally divided in 10 sections. Mean, maximum, minimum and the standard deviation of wood density, for each section were computed. Mean annual growth was used to study the relationships with wood microdensity variables. A linear mixed-effects model computed the significance of different sources of phenotypic variation. Pearson´s correlation computed the relationships between variables. Main results: The pattern of radial variation in E. grandis showed a decrease in wood density from pith to bark, mainly due to the decrease in minimum wood density, while in E. viminalis, wood density increased towards the outer wood. In both species, the standard deviation of the wood density increased along the radial profile from pith to bark. Significant variation in wood density was explained by site, provenance and clone/family effects. In E. grandis mean, maximum and minimum wood density were negatively correlated with mean growth, whereas in E. viminalis correlations were positive but close to zero. Research highlights: Both the pattern of radial variation of wood density and the relationship between wood density and mean growth were different in the studied Eucalyptus species, and they varied within species depending on the site they were growing and genetic provenance.

Tomato Crop Health, Yield, and Greenhouse Soil Conditions after 17 Years of Repeated Treatments of Biofumigation and Solarization

The combination of biofumigation and solarization is known as bio-solarization. An experiment was performed from 2003 to 2019 in a greenhouse at INTA San Pedro, Buenos Aires province, Argentina (33°44'12.7"S 59°47'58.2"W). Treatments (TRAT) were applied every two years. TRAT evaluated were: 1=Control; 2= Solarization, 3= Biorot, a succession of organic amendments (chicken manure, broccoli, chicken manure, broccoli, tomato, and pepper crop debris, mustard, tomato crop debris, broccoli, tomato crop debris), 4=Biobras based only on the use of brassicas (rapeseed, broccoli, mustard, and Brassica campestris). Treatments were carried out in spring or summer so that a late-season tomato crop could be grown after them. The tomato hybrid planted was Superman (Petoseed), except for the last season where the hybrid used was Rodeo (BHN). Fungal pathogens controlled were Pyrenochaeta lycopersici, Fusarium solani, Sclerotium rolfsii, and Sclerotinia sclerotiorum, and nematodes like Nacobbus aberrans, Helicotylenchus and Criconemella. Fungi of Aspergillus genera were observed growing on death sclerotia of Sclerotinia sclerotiorum and Sclerotium rolfsii in Biobras and Biorot. Tomato plants in control showed a higher percentage of dead plants, root rots, and lower root dry matter at the end of each crop. Solarization alone without adding organic matter reduced this parameter in the soil and showed more death plants and less yield than Biobras and Biorot. Tomato and pepper crop debris used as biofumigants produced high yield values and adequate pathogen control. Biofumigation in combination with solarization is an effective technique for managing soil-borne pathogens in greenhouses and is being adopted by horticultural growers in Argentina.

COVID-19: a study about the impact of coronavirus on physicians of La Plata, Argentina

Background: In Argentina, the burden of COVID-19 on health systems and physicians was substantial with difficulties on daily triage decisions which have to be made in the context of grave shortages of basic equipment and consumables. Purpose: this study was performed to understand what physicians were experiencing during the COVID-19 pandemic in La Plata (capital city of Buenos Aires province, Argentina). Methods: A cross-sectional study was performed; a questionnaire was sent by e-mail to physicians who work in this city during November 2020. The questionnaire was made based on Medscape US and International Physicians COVID-19 Experience Report: Risk, Burnout, Loneliness. Statistical analysis: test for normality was performed employing the Kolmogorov-Smirnov test while Chi-square test of independence to examine the relationship between sex and workplace with nominal variables. For categorical variables, Kendall tau correlation was performed to test for independence. ANOVA was developed to examine differences between physician age. Statistical significance was set to p < 0.05 in all cases. All statistical analysis was done employing SPSS Statistics, Version 24 (IBM, USA). Results: 203 physicians answered the questionnaire; the majority of physicians (96%) considered stressful their experience during pandemic and reported distress episodes being for more than 60% the most stressful of their practices, 30% presented depression and were medically treated, while 32.7% felt loneliness with 4 physicians with suicidal thoughts. Conclusion: The results highlight the need to protect the psychological well-being of the healthcare community, and to invest resources to significantly promote the mental health of professionals.