Search

Locusts are globally recognized as major pest threats. In the first half of the 20th century, the South American locust caused great economic losses. After the implementation of preventive management, large‐scale upsurges ceased. In 2015, resurgence of S. cancellata led to swarms affecting northern Argentina, Paraguay, and Bolivia, prompting control agencies to address an almost forgotten problem. After six decades without a major locust outbreak, there were limited and outdated studies on this species. This study aims to identify key environmental factors associated with the spatial distribution of S. cancellata oviposition sites. We focus on explanatory variables that represent physical and chemical properties of soil and vegetation cover. To understand the relationships between each potential explanatory variable and the presence‐absence of S. cancellata oviposition sites, we first performed regression analyses applying a linear and quadratic structure for each explanatory variable. Then, we performed comparisons of logistic regression models in a multi‐model inference framework, where CAIC and weights of evidence were analysed. Our results show that the South American locusts chose to lay their eggs in areas with a low proportion of natural forest and flooded grasslands and a high proportion of non‐vegetated areas, where the soils are flat, with neutral pH, and low salinity. We also determined that an increase in the proportion of cultivated areas is associated with an increase in the probability of breeding presence of this species. The locust's habitat falls within the Dry Chaco, a global deforestation hotspot, evidencing a rapid replacing of forests for plantations. Since both the diminish of forest and the increase in cultivated areas are associated with an increase in oviposition sites, we consider that breeding areas will likely increase. The results found herein can be used to map the potential breeding habitats to help preventive management against the South American locust. [ABSTRACT FROM AUTHOR]

Grasshoppers in the genus Ronderosia (divergence time < 5 Mya) provide a special opportunity to examine the impact of chromosome rearrangements (CRs) in evolution and speciation, because they exhibit extensively rearranged karyotypes involving autosome-autosome and autosome-X chromosomes, the latter leading to the formation of a neo-sex chromosome system (neo-SCS). Despite the potential role of CRs in speciation, the general patterns of karyotype changes resulting from CRs in Ronderosia are still unclear. Here we investigated karyotype evolution in eight Ronderosia species using cytogenetic and phylogenetic models of ancestral character reconstruction. The overall findings suggest a central role for CRs in generating variability in chromosome number and neo-SCS across Ronderosia grasshoppers. It also suggests that incipient species with little morphological change, such as those observed in Ronderosia species, could accumulate marked differences in their karyotypes contributing to post-zygotic reproductive isolation. Besides the evolution of chromosome number in the phylogeny of the genus, chromosome change due to centric fusion is coupled with the divergence pattern observed in the group. While a cladogenetic event could represent a case where karyotypic differences result in speciation, further in-depth genomic studies are needed to better understand how these dramatic restructurings of karyotypes may have occurred. [ABSTRACT FROM AUTHOR]

Bumble bees of the genus Bombus spp. play a key role as effective pollinators in the biodiversity rich Central Andean region; however, parasites and pathogens may negatively influence their abundance and population numbers. In this study, we aimed at verifying the occurrence of these natural enemies in the Andes regions of Bolivia and Peru. Workers and males of Bombus funebris, Bombus opifex and Bombus pauloensis were collected in three localities from highlands at ~1,700 m.a.s.l. Analyses by both optical and molecular techniques revealed the presence of the Apis mellifera filamentous virus (AmFV), the microsporidium Vairimorpha ceranae, the flagellates Crithidia bombi and Lotmaria passim, and five species of mites in the genera Parasitellus Willmann, Pneumolaelaps Berlese, Proctolaelaps Berlese, Tyrophagus Oudemans, and Kuzinia Zachvatkin. Given the potential entry of the allochthonous bumble bee Bombus terrestris to the region, this information is essential to evaluate autochtonous biodiversity conservation strategies. [ABSTRACT FROM AUTHOR]

In an attempt to unveil the origin of neo‐sex chromosomes in Ronderosia Cigliano grasshoppers, we performed a combined phylogenetic analysis based on morphological (external morphology and male genitalia) and molecular data (COI, COII, 16S and ITS2) to explore the chromosome evolution within the genus. We also analysed the distributional patterns of the various Ronderosia species and considered the possible role of chromosome rearrangements (CRs) in speciation processes within the genus in the light of 'suppressed‐recombination' models. We mapped the states of three chromosomal characters on the combined tree topology. The combined evidence supported Ronderosia as a monophyletic group. The cytogenetic analyses of the genus demonstrated the importance of rearranged karyotypes with single, complex and multiples neo‐sex chromosome determination systems in all species. The chromosome character optimisation suggests X‐autosome centric fusion as the mechanism responsible for neo‐sex chromosome formation in most Ronderosia species, except in R. dubia and R. bergii. Similar autosomes were involved in fusions with the ancestral X chromosome in Ronderosia, supporting previous hypotheses on the unique origin of X‐autosome fusion for the sex chromosome in the genus. As a source of chromosome variation, autosome‐autosome centric fusion played a secondary role in Ronderosia compared with other Dichroplini. Given the homogeneity in the morphological features, the sympatric distribution of closely related species and the intrinsic property of centric fusion as suppressors of the crossing over, we suggest that CRs may have played a key role during the speciation process within Ronderosia. We performed a combined phylogenetic analysis based on morphological and molecular data (COI, COII, 16S and ITS2) to explore the chromosome evolution within Ronderosia. We also analysed the distributional patterns of the various Ronderosia species and considered the possible role of chromosome rearrangements (CRs) in speciation processes within the genus.The combined evidence supported Ronderosia as a monophyletic group. The cytogenetic analyses evidenced rearranged karyotypes with single, complex and multiple neo‐sex chromosome determination systems in all species.Given the homogeneity in the morphological features, the sympatric distribution of closely related species and the intrinsic property of centric fusion as suppressors of the crossing over, we suggest that CRs may have played a key role during the speciation process within Ronderosia. [ABSTRACT FROM AUTHOR]

Abstract: The open vegetation biomes, within the limits of the Chacoan subregion, occur along a diagonal in eastern South America covering a large range of environmental conditions. In order to contribute to the knowledge on the biodiversity of these open biomes, we analysed the phylogenetic relationships of the grasshopper genus Zoniopoda to the remaining South American Romaleinae, and examined the biogeographical patterns of diversification of the genus. The study is based on morphological and molecular (COI and H3) evidence, including 12 species of Zoniopoda and 17 species of four tribes of South American Romaleinae. We describe a new species of Zoniopoda, and test its taxonomic placement within the group. Results of our phylogenetic analyses recovered Zoniopoda as a monophyletic group with high support values. According to the dispersion–vicariance analysis, the ancestor of Zoniopoda may have been distributed in an area corresponding to the Chacoan and Cerrado provinces. A vicariant event, that could be explained by the uplift of the Brazilian Plateau and the subsidence of the Chaco, is hypothesized to have occurred splitting the ancestral distribution of Zoniopoda, resulting in the independent evolution of the Tarsata group within the Cerrado and the Iheringi group in the Chacoan subregion. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:act:FCFB4C5D-1741-46F1-8E25-B37ED2B9D872. [ABSTRACT FROM AUTHOR]

We analyze the academic and professional career of Prof. Dr. Ricardo Arturo Ronderos (1928-1995) Past President of the "Sociedad Entomológica Argentina" (SEA) (1964-1979) and Director of its journal (RSEA) (1968-1985). His main achievements and contributions to entomology as well as to other fields of the natural sciences are referred taking into account his academic and professional activities carried on during four decades (1954-1994). We also remark his dedication to the training of young researchers, organization of scientific societies, advice to national institutions of science promotion and international entities, mainly those dealing with environmental assessments of projects affecting aquatic macrosystems of Argentina, Paraguay and Uruguay. [ABSTRACT FROM AUTHOR]

Aim The objectives of this study were to relate species density, richness and relative abundance of grasshoppers to habitat vegetation and to detect variations in these variables among native and exotic plant communities which reflected disturbance history. Location Twenty-seven sites were selected in 2000 representing a variety of native and exotic plant communities, with different degrees of disturbance history, in south-east Buenos Aires province, Argentina. Methods Grasshopper mean density, species relative abundance and species composition were estimated at each site via standard flushing and sweep net techniques. Plant associations at each site were estimated by evaluating the percentage canopy of ground cover of native perennial grasses, introduced perennial forbs, annual pastures, halophilous species, perennial pastures, native perennial forbs, introduced annual forbs and plant species richness. Based on vegetation variables, sites were classified into five disturbance categories: native grasslands, halophilous grasslands, pastures, moderately disturbed pastures and highly disturbed pastures. Results Grasshopper communities from sites dominated by introduced plant species (forbs, sown grasses and dicots), were characterized by relatively high densities and a high proportion of potential pest species. Native grassland sites showed lower grasshopper densities, while halophilous grassland had high densities, but with low proportion of potential pest species. Main conclusions Results from this study suggest that the most abundant and economic important species of the pampas, Dichroplus elongatus, was associated with sown pasture plants (grasses and dicots) and introduced forbs, and negatively correlated with natural communities (native vegetation and halophilous species). These relationships imply that appropriate management practices that leave more areas with natural vegetation and include perennial pastures and native species in the rotations could show... [ABSTRACT FROM AUTHOR]