Southern Cone Of America Research Articles

New Races with Wider Virulence Indicate Rapid Evolution of Puccinia striiformis f. sp. tritici in the Southern Cone of America.

Wheat yellow (stripe) rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most devastating diseases of wheat worldwide. Pst populations are composed of multiple genetic groups, each carrying one or more races characterized by different avirulence/virulence combinations. Since the severe epidemics in 2017, yellow rust has become the most economically important wheat foliar disease in Uruguay. A set of 124 Pst isolates collected from wheat fields in Uruguay between 2017 and 2021 were characterized phenotypically, and 27 of those isolates were subsequently investigated in-depth by additional molecular genotyping and race phenotyping analyses. Three genetic groups were identified, PstS7, PstS10, and PstS13, with the latter being the most prevalent. Two races previously reported in Europe, Warrior (PstS7) and Benchmark (PstS10), were detected in four and two isolates, respectively. A third race, known as Triticale2015 (PstS13), that was first detected in Europe in 2015 and in Argentina in 2017 was detected at several locations. Additional virulence to Yr3, Yr17, Yr25, Yr27, or Yr32 was detected in three new race variants within PstS13. The identification of these new races, which have not been reported outside South America, provides strong evidence of the local evolution of virulence in Pst during the recent epidemic years.

A simplified molecular tool for detecting the Chagas etiological agent using a vector feces sample in field conditions

Triatomine bugs are vectors of Trypanosoma cruzi, the etiologic agent of Chagas disease in the American continent. Here, we have tested a loop-mediated isothermal amplification (LAMP) test for a direct detection of T. cruzi in feces of Triatoma infestans, the main vector of this parasite in the Southern Cone of America. The analytical evaluation showed positive results with samples of triatomine feces artificially inoculated with DNA from strains of T. cruzi corresponding to each Discrete Typing Units (I-VI), with a sensitivity of up to one parasite per reaction. Conversely, the reaction yielded negative results when tested with DNA from Trypanosoma rangeli and other phylogenetically related and unrelated organisms. In triatomines captured under real field conditions (from urban households), and defined as positive or negative for T. cruzi using the reference microscopy technique, the LAMP test achieved a concordance of 100 %. Our results demonstrate that this LAMP reaction exhibits excellent analytical specificity and sensitivity without interference from the fecal matrix, since all the reactions were conducted without purification steps. This simple molecular diagnostic technique can be easily used by vector control agencies under field conditions.

Neuroethology in South America: past, present and future.

South America is a vast continent endowed with extraordinary biodiversity that offers abundant opportunities for neuroethological research. Although neuroethology is still emerging in the region, the number of research groups studying South American species to unveil the neural organization of natural behaviors has grown considerably during the last decade. In this Perspective, we provide an account of the roots and strategies that led to the present state of neuroethology in the Southern Cone of America, with a forward-looking vision of its role in education and its international recognition. Hopefully, our Perspective will serve to further promote the study of natural behaviors across South America, as well as in other scarcely explored regions of the world.

Lethal and repellent effect of amitraz, eugenol and thymol against Triatoma infestans, the main vector of Trypanosoma cruzi in the southern of America.

The lethal and repellent effect of the synthetic insecticide amitraz and the botanical insecticides eugenol and thymol separately and together in binary mixtures was tested against late-stage nymphs of a susceptible strain of Triatoma infestans, the main vector of Trypanosoma cruzi, the etiological agent of Chagas disease, in the Southern Cone of America. For the lethality study, the LD50 was determined for each insecticide alone and in binary mixture by topical application. The combination index (CI) was established to quantify interactions occurring between the insecticides. The repellent effect was tested using the area preference technique. The lethal effect of amitraz was 11 and 34 times more potent than that of thymol and eugenol, respectively. Only the combination of eugenol and amitraz at high concentrations showed a synergistic effect (CI: 0.3). The repellent activity of monoterpenes after 30 min of exposure was significant at 780 and 78 μg/cm2 for eugenol and thymol, respectively. The residual repellent effect of eugenol lasted for one week at the concentrations of 1170 and 1560 μg/cm2 , whereas thymol managed to retain its repellent effect for two weeks at concentrations of 1560 and 3900 μg/cm2 .

Forest Health in the Southern Cone of America: State of the Art and Perspectives on Regional Efforts

The plantation and natural forests of South America have been highly impacted by native and exotic pests in recent decades. The interaction of emerging invasive pests, climate change, and timber markets will define the region’s forests, with significant but uncertain ecological changes and economic losses expected. The Southern Cone Forest Health Group (SCFHG), a joint ad hoc initiative run by forest health professionals from Argentina, Brazil, Chile, and Uruguay, aims to strengthen relationships between the forestry industry, stakeholders, academia, and government agencies across the region. Here, we highlight regional strengths, weaknesses, threats, and opportunities to address forest health issues in the region. A regional approach with a strong communication network is relevant for future actions. In the current global scenario of invasive species and climate change, the implementation of practices that incorporate the resilience of forest ecosystems and sustainable management needs to be prioritized in forest policy across the region. Understanding that pests and pathogens do not recognize borders, we call on governments and organizations to support joint actions with agreements and adequate resources to enhance our regional capabilities.

Palynomorphometry in ferns: Ctenitis (Dryopteridaceae), a case of study in the Southern Cone of America

Abstract The morphometric knowledge about the spores of the Ctenitis has not yet been deepened. Considering the folded spores of this genus which inhabit the Southern Cone of America the aims were to increase infrageneric knowledge, to evaluate the relationship among the morphometric characters of the folded spores in these Ctenitis species and to verify the spore’s morphometry as a taxonomic tool. This study was performed with herbarium material. The spores were analyzed with light microscopy (LM) and scanning electron microscopy (SEM). The variables analyzed were: major and minor equatorial diameter, polar diameter, length of the laesura and length, width and height of the folds. The test chosen to analyze the study variables was ANOVA. Four spore sets are proposed. The “elongate-type” is made up of C. aspidioides and C. nervata. The “medium-type” is made up of C. anniesii, C. distans, C. falciculata and C. paranaensis. The “handle shape-type” is represented by C. bigarellae, C. eriocaulis and C. submarginalis. Finally, the “short-type”, consists only of C. deflexa. The morphometric data of spores together with the statistical analysis provided useful information for the distinction of some Ctenitis species studied in the Southern Cone of America. These results contribute to the studies aeropalynologycal and palaeopalynological.

Defining soybean maturity group options for contrasting weather scenarios in the American Southern Cone

Soybean genotypes are grouped in maturity groups (MG) based on the response to photoperiod, and a genotype belonging to a particular MG is recommended according to latitude and planting date. From an agronomic viewpoint, an “optimum maturity group” (MG opt ) can be defined as the one that maximizes soybean yield in a particular environment, and not necessarily corresponds with the recommended MG based on thermo-photoperiod response. Our objectives were to (i) delineate spatial pattern of MG opt across contrasting environmental conditions for full-season soybean using geostatistics, and (ii) test whether the weather scenario change the spatial distribution of the MG opt . We hypothesized that, for the same region, the MG opt in dry years (i.e. La Niña phase) is larger than in humid years (i.e. El Niño phase). We analyzed multi-environment trials of full-season soybean (1675 site-years) using recent soybean genotypes and management practices across the Southern Cone of America. The MG opt ranged between 3.8 and 7.8 across regions and ENSO phases. The geostatistics approach indicated a spatial MG opt auto-correlation. The map for each ENSO phase indicates zones with contrasting MG opt and independently of ENSO phase, MG opt increased as latitude decreased. Also, for a particular latitude range, MG opt also varied according to longitude, suggesting that its variation can be associated with rainfall pattern and soil types in the region. Our approach delineated the distribution of MG opt for the American Southern Cone and highlighted that the inclusion of ENSO phase is important for guiding farmers MG options at regional scale. • Optimum maturity groups ranged from 3.8 to 7.8 in the Southern Cone of America. • Previous optimum maturity groups definition was improved using spatial analysis. • For a particular latitude, optimum maturity groups also varied according to longitude. • Optimum maturity groups varied with weather scenario in some areas of the Southern Cone.

Forest Stewardship Council Certification of Forest Plantation Management in the Southern Cone of America

Forest Stewardship Council Certification of Forest Plantation Management in the Southern Cone of America

Efficacy of Brief Intervention for Alcohol Consumption during Pregnancy in Argentinean Women: A Randomized Controlled Trial

Introduction Although Brief Intervention (BI) has proven to reduce alcohol consumption during pregnancy in high income countries, there is no evidence from the Southern Cone of America. Thus, we conducted a study to assess BI efficacy among Argentinean pregnant women. Method and Materials We collected data on pregnant women receiving prenatal care at the public health system in Mar del Plata, Argentina. Women with less than 26 weeks of gestation (n = 486) were randomized to brief advice (BA) or BI. Three months later they were re-assessed; women with more than 26 weeks of gestation constituted a screening only control group (SC) (n = 154). Self-reported quantity and frequency of alcohol consumption, frequency of binge drinking, and related problems after three months were used as outcomes. We performed generalized estimating equations and clinical significance analyses. Also, we obtained newborn health indicators from the city’s health system database to use as objective outcomes. Women who did not participate in any of the three former conditions were randomly selected to constitute a non-screening control group (NSC) (n = 150). We compared objective outcomes among BI, BA, and NSC groups using the Wilcoxon rank test. Results In comparison with SC, BI and BA reduced alcohol consumption, without differences between the latter two. Newborns of women who received BI and BA had better health indicators compared with the NSC group. Conclusions performing either a BI or BA reduces alcohol consumption among Argentinean pregnant women and might lead to healthier newborns.

Palynological analysis of the genus Ctenitis (C. Chr.) C. Chr. (Dryopteridaceae) in the Southern Cone of America.

The spore morphology and wall ultrastructure of 12 species of Ctenitis from Southern Cone of America were studied using light microscope, scanning and transmission electron microscope. The study was carried out with herbarium material from Argentine and Brazilian institutions. Equatorial diameters, polar diameters and laesura length were measured. The spores are monolete with echinate or folded ornamentation. In the echinate type, the spines are conical, with broad base and attenuate apex. In the rugate type, the folds are inflated, linear, sinuous, subglobose or handle-shape. The perispore surface is scabrate, rugulate, microverrucose or psilate. Stratification and ultrastructure in the species analyzed are very similar. The exospore is smooth and two-layered in section. Simple and branched channels are observed mainly in the outer exospore. The perispore is composed of two layers, the inner one forms the ornamentation and the outer covers all the outer and inner surfaces. Immature spores were found in all samples of C. fenestralis. The characteristics of the studied spores like macro-ornamentation, color and fold length provide relevant information to differentiate some species or groups of species within the genus.

Alibertia latifolia (Rubiaceae), un nuevo registro para la flora argentina

Alibertia latifolia (Rubiaceae) is registered for the first time in Argentina. This species has a broad distribution in South America and grows mainly in humid forests. It is described and illustrated, we provide a detailed description of its pollen grains, distribution map, and a key to distinguish it from Alibertia edulis, a species also found in the Southern Cone of America.

Genetic structure of two Plusiinae species suggests recent expansion of Chrysodeixis includens in the American continent

The Plusiinae subfamily has many polyphagous species, many of which occur in South America. Chrysodeixis includens and Rachiplusia nu are two representatives that mainly occurs in soybeans, cotton, common beans, sunflower and alfalfa. A population genetic study of C. includens and R. nu collected in the Southern Cone of America was performed using a partial COI gene sequencing data and compared with specimens from other American countries. Six haplotypes were identified in C. includens populations of Brazil, Argentina, Paraguay and Uruguay, organized within a star‐like haplotype network, with the most common haplotype identified as Chin_MC. R. nu populations are more diverse and stable in comparison to C. includens. Populations from Argentina and Uruguay had the highest haplotype diversity, sharing five haplotypes and putatively indicating haplotype exchange. Demographic change analysis suggested a recent population expansion of C. includens over the American continent. Some C. includens haplotypes were country‐specific, suggesting population expansion in the countries where specimens were collected.

Estado e proteção social no Cone Sul da América Latina: um panorama do século XXI

A discussão sobre a proteção social na América Latina deve considerar as características econômicas, sociais e políticas da região, que se constroem e reconstroem historicamente no movimento da sociedade capitalista periférica. Com o objetivo de refletir sobre a relação Estado e proteção social no início do século XXI, este ensaio apresenta um panorama do processo de disputa entre capital e trabalho pelo direcionamento do Estado, por meio da proteção social/desproteção social pública. Apresenta características da sociedade latino-americana e o movimento do Estado no século XXI, entre a ampliação e a retração nos investimentos sociais. Os golpes de Estado são analisados como tentativas de conter avanços sociais e de manter o statu quo, garantindo privilégios de grupos ligados à classe dominante e ao capital financeiro internacional. Por fim, demonstra a necessidade de transformar o formato da proteção social pública no Cone Sul da América para superar os desafios atuais.Palavras-chave: Golpes de Estado. Hierarquias sociais. Pandemia de covid-19.

Borrelia genospecies in Ixodes sp. cf. Ixodes affinis (Acari: Ixodidae) from Argentina

The aim of this work was to evaluate the presence of Borrelia infection in Ixodes sp. cf. Ixodes affinis ticks from Argentina. Specimens of Ixodes sp. cf. I. affinis were collected on vegetation and birds in five locations belonging the most humid part of the Chaco Biogeographic Province. Specimens were tested for Borrelia infection by nested-PCR targeting the flaB gene and the rrfA-rrlB intergenic spacer region (IGS), sequenced and phylogenetically analyzed. A total of 48 Ixodes sp. cf. I. affinis (12 questing adults from vegetation and 20 nymphs and 16 larvae on nine bird species: Arremon flavirostris, Basileuterus culicivorus, Campylorhamphus trochilirostris, Myiothlypis leucoblephara, Tachyphonus rufus, Thlypopsis sordida, Turdus amaurochalinus, Turdus rufiventris and Troglodytes aedon) were collected. Twelve adults, 14 nymphs and 11 larvae (3 individually and 8 in 3 pools) were analyzed. Partial sequences were detected in 6 adults, 11 nymphs and 4 larvae (2 individual and 2 pools). Phylogenetically, the Borrelia found in Ixodes sp. cf. I. affinis belongs to the B. burgdorferi sensu lato (s. l.) complex. The partial sequences obtained from the borrelian gene flaB and IGS were associated to two groups formed by sequences previously detected in Ixodes fuscipes, Ixodes longiscutatus and Ixodes pararicinus from the Southern Cone of America in northern Argentina, southern Brazil and Uruguay. The results of this work suggest that the haplotypes of B. burgdorferi s. l. complex detected in the three species of the I. ricinus complex distributed in the Southern Cone of America are related and widely distributed.

Hemosporidios aviares y gradientes latitudinales: oportunidades y desafíos en el Cono Sur de América

Cuevas, E., Daniela Doussang, D., Cevidanes, A., Quirici, V. 2020. Avian haemosporidian and latitudinal gradients: opportunities and challenges in the Southern Cone of America. Ecosistemas 29(2):1974. https://doi.org/10.7818/ECOS.1974 Latitudinal diversity gradients (LDG) explain the distribution and species richness in free-living organisms of multiple taxa, where richness increases toward low latitudes. However, parasites have shown inconsistencies to this spatial pattern. In the case of avian haemosporidians (Plasmodium, Haemoproteus and Leucocytozoon), they have shown differences depending of the genera and geographic scale. Thus, at global scale none of the three genera presents a latitudinal gradient of diversity. In South America, Plasmodium and Haemoproteus present a LDG, and the prevalence shows the same pattern in local Chile. In contrast, Leucocytozoon exhibits an inverse latitudinal pattern at the continental level and in Chile, where diversity and prevalence are associated with high latitudes. The climatic and habitat characteristics of the Amazon represents great influence to maintain the interactions of Plasmodium and Haemoproteus with their vectors and hosts but represent an environmental filter for Leucocytozoon. Despite the important role of vectors in the maintenance of LDG for avian haemosporidians, this approach has not been incorporated in any study in the region. Finally, biogeographic barriers, such as the Andes mountain range could interrupt the dispersal of lineages from the Amazon to other regions, like the Southern Cone of America. Thus, countries such as Chile and Argentina present extraordinary geographical characteristics to explore hypotheses associated with local dispersion and/or diversification processes.

Molecular detection of rickettsial bacteria in ticks of the genus Ixodes from the Southern Cone of America

To obtain information about rickettsial bacteria in ticks of the genus Ixodes from Argentina and Uruguay, specimens of I. fuscipes (previously named as I. aragaoi), Ixodes pararicinus, Ixodes sp. cf. I. affinis, and Ixodes sp. were tested targeting the rickettsial gltA and ompA genes. Rickettsial bacteria was detected in all of these species. Rickettsia found in Ixodes sp. is closely related to Ca. Rickettsia mendelii, which was previously detected in I. ricinus of the Czech Republic and later in I. brunneus from the USA. Phylogenetic analyses of the Rickettsia strains found in I. fuscipes, I. pararicinus, and Ixodes sp. cf. I. affinis showed that these strains form a clade together with R. buchneri detected in I. scapularis from the USA, which is closely related to R. monacensis from Europe. Rickettsia buchneri, R. cooleyi and the Rickettsia detected in I. fuscipes, I. pararicinus, and Ixodes sp. cf. I. affinis clustered together in a clade well supported, which suggest that they are different strains of R. buchneri. The phylogenetic analysis shows that Ixodes ticks that are closely related in evolutionary terms (i.e. Ixodes species from the I. ricinus complex, I. brunneus-Ixodes sp.) share closely related rickettsial strains. The results of this study show that rickettsial bacteria are present in Ixodes ticks from Argentina and describe the first detection of Ca. R. mendelii in South America.

Resistance to deltamethrin in Triatoma infestans: microgeographical distribution, validation of a rapid detection bioassay and evaluation of a fumigant canister as control alternative strategy

Triatoma infestans (Klug) (Hemiptera: Reduviidae) is the main vector of Chagas disease in the Southern Cone of America and resistance to pyrethroid insecticides has been detected in several areas from its geographical distribution. Pyrethroid resistance presents a complex geographical pattern at different spatial scales. However, it is still unknown if the toxicological variability is a common feature within villages of the Gran Chaco were high resistance was descripted. The objectives of this study were to determine: (a) the microgeographical distribution of the deltamethrin-resistance in insects from Pampa Argentina village, (b) the performance of the insecticide impregnated paper bioassay to evaluate deltamethrin-resistance in field collected insects and (c) the lethal activity of the fumigant canister containing DDVP against insects resistant to deltamethrin. High survival of T. infestans exposed to discriminant dose was observed in the samples of all the evaluated dwellings, suggesting that the resistance to deltamethrin is homogeneous at the microgeographical level. Resistance determination by impregnated paper bioassay was similar to traditional topical determination, highlighting the use of this rapid methodology in field large-scale monitoring. The fumigant canister was not effective against resistant insects, remarking the need to develop suitable formulations that ensure minimal toxicological risk and high effectivity.

The Ixodes ricinus complex (Acari: Ixodidae) in the Southern Cone of America: Ixodes pararicinus, Ixodes aragaoi, and Ixodes sp. cf. I. affinis.

The goal of this study was to clarify the taxonomic status of the Ixodes ricinus complex in the Southern Cone of America, by using morphological characters and molecular markers (mitochondrial 16SrDNA and cox1 genes). The morphological analysis indicates that three different taxa of the I. ricinus complex occur in this region: Ixodes pararicinus, Ixodes aragaoi, and Ixodes sp. cf. I. affinis. The most prominent diagnostic character among them is the size of scutal punctations in both male and female ticks. In the males of Ixodes sp. cf. I. affinis, the punctations on the central field and along the median marginal groove of the scutum are clearly larger than in the males of I. aragaoi and I. pararicinus, while the punctations of I. aragaoi are larger but less numerous than in I. pararicinus. The punctations in Ixodes sp. cf. I. affinis females are larger and deeper than in females of I. aragaoi and I. pararicinus, and those of I. aragaoi are slightly larger than in I. pararicinus. The length of the lateral posterior denticles of the male hypostome is comparatively longer in I. aragaoi than in the other two species, and longer in Ixodes sp. cf. I. affinis than in I. pararicinus. In the 16S analysis, I. pararicinus and I. aragaoi are monophyletic (99% and 98% bootstrap support, respectively), while Ixodes cf. I. affinis does not represent a single lineage. In the cox1 analysis, both I. pararicinus and I. aragaoi are well-defined taxa, but the bootstrap support for Ixodes sp. cf. I. affinis is low (67%). In general, there are considerable 16SrRNA differences among lineages of Ixodes sp. cf. I. affinis from different geographical areas. These results may be indicative of the existence of different species. The populations morphologically compatible with I. affinis from Argentina, Colombia, Panama, Belize, and USA should be provisionally named as Ixodes sp. cf. I. affinis until an integrative taxonomic work with further evidence redefines whether or not this taxon actually represents a species complex.

New morphological key using male prothoracic leg characters to identify Helicoverpa (Lepidoptera: Noctuidae) species

Since invasion of Helicoverpa armigera (Hübner) in South America, identification of Helicoverpa species became essential for Integrated Pest Management (IPM). Thus, we worked out on a pictorial key to identify tree important Helicoverpa species that occur in the Southern Cone of America, using new morphological characters from the prothoracic legs. Adult male and female of Helicoverpa zea (Boddie), H. armigera, and Helicoverpa gelotopoeon (Dyar) were used for identification. Prothoracic legs from moths were removed and images were taken (magnification of 25X) with scales and specialized scales. In addition, images (magnification of 50X) of prothoracic legs were used to measure the foretibia and epiphysis. The results showed that measurable characters were more reliable and accurate on male moths than female moths. For this reason, we will show only detailed results of male moths. Foretibia of H. zea were longer than H. gelotopoeon, but shorter than H. armigera. This size is visible with or without scales and specialized scales on males. Here, we show a first detailed description of protibial epiphysis. H. armigera has the longest epiphysis with fore margin pointed and with bristles terminating before the end of epiphysis. This illustrated pictorial key shown some first detailed descriptions of prothoracic legs. These characters are useful on integrated pest management programs of many crops to identify male representatives of Helicoverpa, which are captured on pheromone traps.

Wild owls colonized by international clones of extended-spectrum β-lactamase (CTX-M)-producing Escherichia coli and Salmonella Infantis in the Southern Cone of America

Extended-spectrum β-lactamases (ESBLs)-producing Enterobacteriaceae have been classified as critical priority pathogens by the World Health Organization (WHO). We have conducted a microbiological and genomic surveillance study, in order to investigate the occurrence and features of antibiotic-resistant bacteria in wild birds admitted to a wildlife rescue and rehabilitation centre in Chile. This study reports for the first time the occurrence of highly virulent ESBL-producing Escherichia coli and Salmonella enterica serovar Infantis in wild owls inhabiting the Southern Cone of America. Genomic analysis revealed a wide resistome (for antibiotics, heavy metals and disinfectants) among international lineages of E. coli belonging to ST345 and ST2705, and S. Infantis ST32, producing CTX-M-8 or CTX-M-65 ESBLs. On the other hand, wide virulome was associated with a highly virulent behaviour in the Galleria mellonella infection model. Worryingly, all these lineages have been previously reported in humans, supporting that wide resistome and virulome could be contributing to rapid adaptation and dissemination of these clones at the human-animal-environment interface. In summary, wild owls can constitute environmental reservoirs of international clones of ESBL (CTX-M)-producing E. coli and S. Infantis carrying a wide resistome and virulome, in the Southern Cone of America, with potential risks to human, animal and environmental health.