1,720,999 research outputs found
Long-term quantification of leaf-cutting ant damage in willow forestations in the lower delta of the Paraná River, Argentina
Get PDF1. Leaf-cutting ants are major pests of Neotropics forest plantations. The lower delta of the Paraná River contains the main Argentine Salicaceae production, strongly attacked by Acromyrmex lundii and Acromyrmex ambiguus. Nevertheless, there is no damage quantification in willow plantations attributed to leaf-cutting ant species.
2. In an area without leaf-cutting ant control, we installed 15 blocks with eight willow stakes each: four clones two treatments; with and without leaf-cutting ant exclusion. We used two traditional (Americano, Nigra 4) and two new (Géminis, Yaguareté) commercial clones. During 2014–2018, we measured the damaged foliage, height and diameter of each tree.
3. Foliage was damaged intensely during the first 2 years. After 1537 days, the loss in height and diameter was greater in Americano (70%), followed by Géminis (50%–60%), Yaguareté (40%–50%) and Nigra 4 (45%–40%). Stake survival with exclusion was greater (>80%) than stakes without exclusion (<50%). Total loss of wood volume was 93% for Americano, followed by Géminis (77%), Yaguareté (66%) andNigra 4 (51%).
4. Although the new clones were heavily attacked, they produced two to three times more wood volume than Americano; replacing Americano with the new clones would help to reduce leaf-cutting ants impact on plantations and pesticides
released into the environment.Fil: Jiménez, Nadia Lis. Fundación para el Estudio de Especies Invasivas; Argentina.Fil: Jiménez, Nadia Lis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Farji-Brener, Alejandro G. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Farji-Brener, Alejandro G. Laboratorio de Investigaciones en Hormigas; Argentina.Fil: Farji-Brener, Alejandro. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; Argentina.Fil: Calcaterra, Luis Alberto. Fundación para el Estudio de Especies Invasivas; Argentina.Fil: Calcaterra, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Dominance of a highly invasive ant is limited to the nesting territory of its supercolony
No full text1. Ant invasions represent a serious threat to biodiversity, agriculture and publichealth. Highly invasive ant species exhibit a very high abundance within its introducedrange and cause severe impacts on native ant communities. This scenariotends to be different within the native range, where competitor ants may limit itsaccess to food sources, thus its abundance.2. Here, we evaluated the competitive ability of a typical clonal and supercolonialnative population of Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae)in Argentina. We used a combination of pitfall traps and food baits to study the antinteractions within an assemblage where W. auropunctata coexists with anothergreat invader, Solenopsis invicta (Buren) (Hymenoptera: Formicidae).3. The studied assemblage presented 56 ant species/morphospecies. AlthoughW. auropunctata was the most abundant numerically, its ability to discover baitswas intermediate, and its ability to recruit workers massively and monopolise baitswas low. Wasmannia auropunctata was not successful defending baits nor attemptingto usurp baits dominated by other species.4. Moreover, it lost all contests against S. invicta, one of the most ecologically dominantspecies in this assemblage. Wasmannia auropunctata dominated food sourcesonly when they were located within the nesting territory of its supercolony.5. Within the native range, clonality and supercoloniality may favour the local numericalabundance of a highly invasive ant but may not be enough to achieve ecologicaldominance. This study sheds light on the important role of biotic interactions as akey factor that may limit the dispersal of invasive species.Fil: Chifflet, Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Calcaterra, Luis Alberto. Fundación para el Estudio de Especies Invasivas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Local co-occurrence of several highly invasive ants in their native range: are they all ecologically dominant species?
Get PDFAn important goal of invasion ecology is to understand the colonization, establishment, and spread of exotic species. To accomplish this, it is essential to examine the ecology of introduced species in native populations. We examined organization patterns, spatial structure, and competitive abilities of ground-dwelling ants in different habitats of a protected area in east-central Argentina, where several highly invasive ant species naturally coexist, to determine whether all they are ecologically dominant in their native range as in their introduced range. We sampled ant communities at Otamendi Nature Reserve and found 49 ant species co-occurred with moderate separation among habitats, including five species that are global invaders; but only Solenopsis richteri (the most numerically dominant) and Linepithema humile (the best mass recruiter) were ecologically co-dominant along with another three non-invasive species in locally rich assemblages. Their co-occurrence was apparently facilitated by both niche and competitive differences. However, we found no evidence for discovery-dominance trade-offs, and ant diversity and spatial segregation suggested that competition only plays a secondary role in structuring assemblages in arboreal habitats. Despite L. humile and S. richteri were ecologically co-dominant, their hegemony was lower in the reserve than in their introduced range likely due to biotic resistance. The other invasive ants (Wasmannia auropunctata, Brachymyrmex patagonicus, and Nylanderia fulva) were not dominant. It is possible that their establishment, persistence, and high prevalence in anthropic habitats in native and introduced populations to be attributed to their better physiologic adaptations to disturbed habitats rather than to their superior competitive abilities.Fil: Calcaterra, Luis Alberto. Fundación para el Estudio de Especies Invasivas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sonia, Cabrera. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Briano, Juan. Fundación para el Estudio de Especies Invasivas; Argentin
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Ant species (Hymenoptera: Formicidae) in the three forests of the ischigualasto provincial park, a protected area of the monte desert, Argentina
Get PDFDeforestation and over-grazing mediated by the humans have caused a serious process of desertification in the Argentine Monte Desert, which threats biodiversity of this ecosystem. Forests provide important resources and refuge for animal species, such as ants. The objective of this work was to survey the ant fauna of dryland forests of Ischigualasto Provincial Park, a protected area located in the hyper-arid Monte Desert ecoregion in the province of San Juan, Argentina. Ant species were surveyed in summer in three types of forests (Prosopis, Ramorinoa and Bulnesia forests), using a combination of sampling methods: pitfall-traps, baiting, and hand collection. A total of 33 ant species were collected, of which 17 are new records for the Monte Desert and Dry Chaco and 24 for the San Juan province. The species richness is within the range reported for other Argentine desert and semi-desert areas. Prosopis forest was the richest with 32 species (24 exclusive), followed by Ramorinoa and Bulnesia forests with 11 and 4 species, respectively. This study contributes to improve the knowledge of ant fauna in desert habitats of the world, especially those inhabiting Prosopis forests, which are the most important ant diversity hotspots within the hyper-arid desert.Fil: Amatta, Emilce del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Calcaterra, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Giannoni, Stella Maris. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentin
- …
