1,720,980 research outputs found
Effects of exposures to repeated heat stress on the survival of the pea aphid Acyrthosiphon pisum and its endoparasitoid Aphidius ervi
Full text linkOrganisms could be exposed to several heat waves during their life, and their ability to survive a heat wave strongly depends on the effects of the previous one. Exposure to extreme temperatures can have important effects on the outcome of host-parasitoid interactions, as the ability of the parasitoid to survive depends on the ability of its host to cope successfully with these stresses. In the present study we address the impact of repeated exposure to heat stress on the survival of the pea aphid Acyrthosiphon pisum (Harris)
(Hemiptera Aphididae) and its endoparasitoid Aphidius ervi Haliday Hymenoptera Braconidae). The first treatment consisted of a heat stress of 35 °C for 30 minutes performed on 4 days old aphids, the second and third heat stresses of 39 °C were performed on 5 days old and on adult aphids, espectively. The three treatments were applied alone or in all their ombinations. We found that aphid thermal tolerance is positively influenced by heat hardening if a severe stress occurs a few days after the first event. Adult
parasitized aphids show significantly higher survival than unparasitized ones; however, the effects of parasitization and hardening on host survival after heat shock are not additive. We also found that A. ervi has a lower thermotolerance capacity than its host and does not show apparent hardening effects. In addition, parasitoid survival after mummification is not affected by the previously experienced heat shock. The possible explanations of the observed phenomena are discussed
A survey of potential vectors of the plant pathogenic bacterium xylella fastidiosa in the basilicata region, italy
No full textThe plain along the Ionian coast and the Matera hills are close to the border of the Apulia region, where, since 2013, the bacterium Xylella fastidiosa has been causing the death of olive trees. During 2016-2018 a study was conducted on the potential insect vectors of X. fastidiosa in eight olive groves, located in three areas of the province of Matera (Basilicata, Italy), characterized by different agricultural landscapes. We captured three spittlebug species, Philaenus spumarius (L.), Neophilaenus campestris (Fallen) and Lepyronia coleoptrata (L.), in addition to the cicadellid Cicadella viridis (L.). Among them, P. spumarius was by far the most prevalent species in 2016, while in 2017 and 2018 catch rates were modest for all the candidate vector species. The population trend of the four insect species in the June-October period was reported about the three study areas in the years considered
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Paradigm shifts in research assessment for scientific publishing: emerging models in a pluriverse perspectives
No full textIn the realm of design, research publication undergoes a transformative shift in evaluation and emerging forms that prompt investigation into the distortive impact of the current assessment framework on publication diversity. The complexity of assessing research quality within institutional frameworks and career metrics hinders innovation, and globally, debates on impact factors drive a shift to qualitative, responsible evaluation. The article explores how collaborative methodologies enable new assessment practices for design communities in the Global South, challenging Western-centric peer-review norms to adopt a more pluriversal perspective. It includes an introduction problematising the status of publication assessment in the general scientific domain. The paradigm of pluriversality is then introduced as a background framework to discuss and nurture new opportunities in the assessment of scientific research and publication in the design field and adopted as a reference in two proposals, shown in the case studies
Variations on the Author
Full text link“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
Full text linkWe 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
Intraguild predation between macrolophus pygmaeus and Aphidius ervi
Full text linkThis work investigates the intraguild predation (IGP) between the predator Macrolophus pygmaeus Rambur (Hemiptera Miridae) and the aphid parasitoid Aphidius ervi Haliday (Hymenoptera Braconidae). In particular, predation on parasitized Acyrthosiphon pisum (Harris) (Hemiptera Aphididae) aphids was studied at two different stages of parasitism. It is known that A. pisum parasitized by A. ervi exhibits a „suicidal‟ behaviour in presence of a coccinellid. This behaviour may be linked to an increased risk of being preyed, since it has been observed that parasitized A. pisum suffers greater predation rate by Harmonia axyridis (Pallas). The escape response in A. pisum is affected by predator species and hemipterans cause a small disturbance of aphid colony. We hypothesize that parasitized A. pisum at an early stage of parasitization would suffer higher predation risk also if the predator is a hemipteran. We used the generalist predator M. pygmaeus to test this hypothesis. Predation on newly parasitized aphids was tested by offering groups of twenty 2nd instar aphids composed of parasitized and unparasitized individuals in different proportions to the predator. The relative proportion of the healthy and parasitized aphids did not change the total prey consumption. Increased susceptibility to predation for parasitized aphids at an early stage of parasitism was observed. This result is discussed on the basis of the kin selection theory. Predation on pre-mummified and mummified A. pisum aphids was also studied. Our results show that M. pygmaeus preys, on average, about two A. pisum mummies in 24 h, which is fully in line with the consumption of fourth instar aphids. Pre-mummies killed by M. pygmaeus always showed visible damage while mummies did not always show visible signs of the predator feeding activity. The possible consequences of the mass release of generalist predators on parasitoid natural populations are briefly discussed
The age of tomato plants affects the development of Macrosiphum euphorbiae (Thomas, 1878) (Hemiptera) colonies
No full textWe tested the hypothesis that the intensity and duration of Macrosiphum euphorbiae infestations in tomato depend on both the age (phenological stage) of the host plant and the initial number of aphids present in the colony. We compared the effects of three initial levels of infestation and two phenological stages of the plant (pre-flowering and flowering stages) on infestation curves. The position of the infestation peak over time was significantly affected by the plant phenological phase. Populations of M. euphorbiae reached the highest peak of abundance on plants infested at the pre-flowering stage compared to those subsequently infested. Within a phenological phase, the maximum abundance also varied according to the initial aphid density on the plant. The implications concerning the management of the pest in the field are briefly discussed
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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