1,720,958 research outputs found
Biology and ecology of Eucalyptus psyllid pests in South Africa
No full textThesis (PhD)--University of Pretoria, 2022.As with other invasive insect pests, eucalypt-feeding psyllids can cause significant economic loss of eucalypts globally. Currently, the Eucalyptus plantations in South Africa are hosts to a number of eucalypt-feeding psyllids, namely Spondyliaspis cf. plicatuloides (Froggatt), Glycaspis brimblecombei Moore, Ctenarytaina eucalypti (Maskell) and Blastopsylla occidentalis Taylor. To better understand the threat of eucalypt-feeding psyllids to this industry globally, a comprehensive review of their diversity, distribution, biology and impact was compiled. Beside their high diversity in Australia, the review points out how little we know about psyllids reported as invasive for the first time, such as S. cf. plicatuloides, a recent introduction in South Africa. To manage eucalypt-feeding psyllids, long-term strategies, including resistant genotypes and parasitoids are required, which also requires a thorough understanding of their biology and seasonality. In a first part of this study, the biology of S. cf. plicatuloides was studied under controlled conditions using Corymbia ficifolia as the host. Females reached reproductive maturity two days after eclosion and on average laid 16 eggs/female. The first nymphal instars took approximately 11 days to hatch from the eggs. Five nymphal instars completed their development in about 23 days under the lerps. The insect’s total life cycle lasted approximately 37 days. Male and female longevity averaged about four and six days respectively. Factors influencing host preferences of S. cf. plicatuloides and G. brimblecombei are also unknown. For this reason, potential morphological and phytochemical leafy features were assessed in six preferred and six non-preferred eucalypt species in a second research chapter of the study. None of the morphological features were related to host preferences. GC/MS determined the composition of essential oils and polar metabolites in and on the surface of leaves. The abundance of certain terpenes, diterpenes, triterpenes, phenylpropanoids, organic and fatty acids was related to host preferences. Results suggest that leafy phytochemistry, rather than leafy morphology, influences host preference for both psyllids. A third part of the study assessed host specificity and host stage preference of three psyllid parasitoids namely Psyllaephagus blastopsyllae, P. pilosus, and P. bliteus, choice and no choice experiments towards the four invasive psyllids were evaluated. Results revealed that two Psyllaephagus spp. are not host specific, whereas one was highly host specific. Furthermore, all the tested parasitoids preferred third and fourth nymphal instars for oviposition. In a final part of this study, seasonal occurrence of S. cf. plicatuloides in South Africa was initiated, which covered all the life stages in three distinctive sites. Moreover, a first-time study to determine the seasonal occurrence of the adults of other invasive eucalypt-feeding psyllids namely B. occidentalis, C. eucalypti and G. brimblecombei was initiated. The initial results of these studies are presented, but additional data is needed to validate the pattern of psyllids’ seasonality. In conclusion, the current study provides foundational information on the biology, host preference, interactions with natural enemies, and seasonal occurrence of the newly reported psyllid, S. cf. plicatuloides, as well as other eucalypt-feeding psyllids in South Africa, which will inform knowledge-based management programs and future research.Zoology and EntomologyPhDUnrestricte
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
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Biology of the invasive shell lerp psyllid, Spondyliaspis cf. plicatuloides (Froggatt) (Hemiptera: Aphalaridae)
Full text linkSpondyliaspis cf. plicatuloides (Froggatt) (Hemiptera: Aphalaridae) is native to Australia but was first detected outside its native range in 2014, in South Africa. It feeds on eucalypt species and thus has the potential to become a pest in commercial Eucalyptus plantations. Information on the basic biology of this insect, which is important for the development of surveillance and management strategies, is lacking. To investigate the life cycle and general biology of S. plicatuloides, the psyllid was reared under controlled glasshouse conditions on potted red-flowering gum, Corymbia ficifolia. The egg incubation period, number of nymphal instars and their developmental time, adult fecundity, adult longevity and duration of the life cycle were determined. The major diagnostic features used to differentiate the five nymphal instars were the number of antennal segments, wing pad development and body length. Females reached reproductive maturity 2.3 ± 0.47 (mean ± SD) days after eclosion and laid 16.2 ± 3.9 (mean ± SD) eggs on average. Reproduction was sexual. The first nymphal instar took 10.7 ± 1.2 (mean ± SD) days to hatch from the egg. The nymphal instars completed their development in 22.6 ± 1.4 (mean ± SD) days under the brown scalloped shelters they secrete. The insect's total life cycle lasted 37.37 ± 1.17 (mean ± SD) days from egg to adult death. Males and females lifespan is also reported. The study provides the first information on the basic biology of S. cf. plicatuloides that will be useful for future studies on surveillance and management strategies
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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