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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
Environmental and physiological correlates of response by three fruit fly (Diptera: Tephritidae) species to commercial lures
No full textDissertation (MSc (Entomology))--University of Pretoria, 2024.Traps are important tools for managing economically damaging pest fruit flies (Diptera: Tephritidae). Trap captures help fruit and vegetable producers to monitor fruit fly populations and shape their pest management action thresholds. However, biotic, and abiotic factors influence how fruit flies respond to attractive stimuli used in traps. Physiological changes within a fly can change its resource orientated behaviours. In a similar manner, environmental changes can limit or encourage insect activity that governs this behavioural response. Consequently, baited traps only catch subsets of the population under certain weather conditions. Understanding how fruit fly lure responses change is important for improving interpretation of trap captures with direct benefits for fruit fly monitoring and management programmes. In this dissertation, I aimed to test how fruit fly physiology, the environment, and lure weathering impact lure response. I assessed the response of three economically important fruit fly species to several commercial fruit fly lures. To do this I released known numbers of flies in field cages, which enabled unambiguous measurement of the relative response of species to lures under the experimental conditions. The response of Ceratitis capitata (Wiedemann) was tested for BioLure, E.G.O PheroLure and trimedlure. The response of C. cosyra (Walker) was tested for BioLure and E.G.O PheroLure, while the response of Bactrocera dorsalis (Hendel) was measured for BioLure and methyl eugenol. For each species and lure combination, response by a group of flies (n=25) was determined in a semi-field setting in relation to sex, diet (protein deprived and protein rich), and age (two-, 10-, and 20-days post emergence). The effect of nutrient reserves (protein, lipid, and carbohydrate content), and body weight on lure response was also quantified using colorimetric biochemical assays adapted from van Hendel’s method. The environmental effects of temperature (°C), relative humidity (%RH), and light intensity (lux) on lure response were also measured. Additionally, the effects of temperature and relative humidity on the weathering of the lures BioLure, E.G.O PheroLure, methyl eugenol and Capilure (trimedlure mixed with extenders) was evaluated in a field setting. The. The weight of each lure was measured at daily intervals for 30 days to determine weight loss of each lure product in relation to daily mean temperature and relative humidity. Additionally, I tested the effect that semiochemical pre-release feeding, diet (protein rich and iii protein deprived), and age (four-, 10-, and 20-days post emergence) had on the response of B. dorsalis males (n=20) to methyl eugenol baited traps in a field cage setting. Semiochemicals were fed to flies 48 hours prior to field cage testing, with methyl eugenol, eugenol, or no semiochemicals (control) being tested. Semiochemicals were mixed into the relevant diet treatment food at a concentration of 1.5%. I further assessed the effects that body weight and total body nutrient composition (protein, lipid, and carbohydrate content) had on the response of B. dorsalis to methyl eugenol. Body nutrient composition data was obtained with the revisited van Hendel’s method which uses colorimetric biochemical assays. The effect that temperature (°C), relative humidity (%RH), and light intensity (lux) had on the response of B. dorsalis to methyl eugenol lures was also measured. Overall, the effect of fly physiology and the environment on response is specific to the species and lure tested. Despite BioLure being considered a female biased lure there was no consistent bias towards female captures. Only in C. capitata were protein deprived females more likely to respond to BioLure. Irrespective of species, access to dietary protein decreased the response to BioLure baited traps. This suggests that abundant natural sources of protein may decrease the accuracy of fruit fly monitoring that relies on BioLure as the main attractant. Age affected the response of flies to male lures. Immature C. capitata and C. cosyra responded more strongly to E.G.O PheroLure and trimedlure. However, immature B. dorsalis were the least responsive to the male lure methyl eugenol. I found that the effects of temperature on response are largely lure and species specific. The response of B. dorsalis increased at warmer temperatures irrespective of the lure tested. Similarly, the response of flies to male lures increased with temperature. However, I observed that the response of C. capitata and C. cosyra to BioLure is not affected by temperature. Warmer temperatures resulted in greater lure weight loss for all tested lures, but this occurred to varying degrees. Combining the results of lure volatilisation and fly response, I identified that the increased response of C. capitata males to trimedlure at warmer temperatures is mostly driven by increased fly activity. Whereas increased response of C. capitata and B. dorsalis to E.G.O PheroLure and methyl eugenol, respectively, at warmer temperatures coincides with greater release rates of the lures. These results show that monitoring conducted when temperatures are cooler is likely to underestimate fruit fly populations. Feeding on either methyl eugenol or eugenol reduces the response of B. dorsalis males to methyl eugenol baited traps by similar amounts. Access to dietary protein had little effect iv onthe reduced response by males to methyl eugenol when fed semiochemicals. This suggests that feeding semiochemicals to B. dorsalis males may facilitate the simultaneous application of the sterile insect technique and the male annihilation technique. Furthermore, this shows that protein supplementation will not counteract the methyl eugenol response suppression induced by pre-release semiochemical feeding. These results also show that eugenol is a promising alternative to methyl eugenol to achieve the required reduction in response to methyl eugenol. Overall, this dissertation highlights that fly physiology and the environment significantly impact the response of fruit flies to commercially used lures. Specifically, access to natural sources of protein may decrease the accuracy of trap surveys that rely on BioLure. The minimal response of flies occurring at temperatures below 12 °C indicates that trapping surveys deployed below this will largely misrepresent population sizes and are likely to miss incipient fruit fly incursions. It is thus crucial to integrate fruit fly physiology and environmental variables into fruit fly monitoring and survey programmes to increase their accuracy. My results further indicate that eugenol is an effective and safe semiochemical that can be used in joint MAT-SIT programmes. I also observed that protein supplementation and semiochemical pre-release feeding can occur simultaneously in MAT-SIT programmes without increasing the response of B. dorsalis to methyl eugenol. Overall, this dissertation highlights the complex nature of tephritid lure response and the value that quantifying and integrating these effects into monitoring and control programmes can have on fruit fly management.Citrus Research International (Project 1229) and the International Atomic Energy Agency (CRP D41027) funded this project.Zoology and EntomologyMSc (Entomology)UnrestrictedFaculty of Natural and Agricultural SciencesSDG-15: Life on lan
Initial steps for developing large-scale rearing and processing of black soldier flies, Hermetia illucens L., in a start-up bioconversion facility
No full textThesis (PhD (Applied Entomology))--University of Pretoria, 2024.The aim of this project was to establish large-scale rearing and processing methods for Hermetia illucens L. larvae reared on organic waste streams for use in animal feed. This work builds on existing knowledge of the effects of organic waste streams as larval substrates, and waste mixing to optimise larval development on substrates with variable nutrient content. The experiments were conducted at an industrial scale using thousands of larvae fed many kilograms of feed, rather than at a lab scale (hundreds of larvae fed grams of feed) in a newly established bioconversion facility that was still optimising its processes. As such, the results are more applicable to large-scale, commercial bioconversion operations. The results also provide insights into the processing methods and safety of insects reared on organic waste as animal feed supplements, and provide some guidance on the optimal substrate composition for improved performance of larvae, bioconversion and waste reduction.
Following an in depth literature review (Chapter 1), four different experiments were conducted. For all experiments, freshly hatched H. illucens neonates were collected from an established colony held at Aegis Environmental Bioconversion Facility, Centurion, South Africa. Preconsumer fruit and vegetable waste was sourced from a local fresh produce market and poultry manure was sourced from a local chicken layer hen farm. The first three experiments were conducted with 12 kg of waste and 90 mg (approximately 6000) neonates in large plastic meat trays. All trays were held at 28 ± 0.5°C with 65% relative humidity. Measurements of the larvae were taken to determine the development time, size, biomass production, survival, bioconversion, efficiency of conversion of digested feed, and waste reduction, collectively referred to as larval performance.
The first experiment (Chapter 2) focused on the nutritional differences between larvae and prepupae (harvested at 15 and 20 days, respectively) that had been fed fruit and vegetable waste. Prepupae had slightly higher fiber content than larvae, and no other nutritional differences were found. Larvae had higher total biomass and higher survival rates. Based on the results of this experiment, larvae should be harvested in preference to prepupae to maximise waste reduction and biomass production. However, harvesting a mixture of larvae and prepupae should not impact the nutritional quality of the final product due to the minimal nutritional differences between the two stages.
The second experiment (Chapter 3) investigated the effects of three different drying methods on the nutritional composition and microbiological contamination present in H. illucens larvae. A sample of 280 g of 15-day old larvae, fed on fruit and vegetable waste and euthanized using boiling water, was used. There were no nutritional or microbiological differences between hot air, oven or microwave drying. A cost benefit analysis of each drying method was completed, and it was determined that hot air drying, followed by oven drying were the most cost-effective while microwave drying was expensive and unprofitable. If there is no effect on the nutritional or microbiological content of H. illucens larvae, the best drying method is the one that is most cost effective and time efficient.
The third experiment (Chapter 4) investigated the performance of larvae fed varying mixes of fruit and vegetable waste and poultry manure, and it was determined that larvae performed best on fruit and vegetable waste only but tolerated up to 60% fruit and vegetable waste mixed with 40% poultry manure before the performance of the larvae was severely reduced. In terms of using poultry manure as a substrate for H. illucens larvae, it should be added only in low quantities, up to 40% total wet mass of the substrate.
The final experiment (Chapter 5) used large, specifically designed metal trays with 60 kg of waste and 450 mg (approximately 30 000) neonates. The effect of poultry manure inclusion, from 5 to 40%, with fruit and vegetable waste was assessed and temperature and pH of the trays were recorded throughout development of the larvae. There was no effect of mixing poultry manure with fruit and vegetable waste at different inclusion percentages on any measure of larval performance. However, temperature and pH of the substrate were key factors in development, survival and waste reduction potential of H. illucens larvae. This study showed that a substrate temperature of 28°C, an initial substrate pH of 6.3, and a final pH of around 9.6 is ideal for larval performance and waste reduction when larvae are fed a mixture of fruit and vegetable waste with a small portion of poultry manure. Comparing the results between Chapter 4 and Chapter 5, specifically trays that contained 40% poultry manure, larvae performed better overall in medium-sized trays, although individual larval masses were similar between both tray types. This study indicates that medium-sized experiments do not scale up in a predictable manner, making it more difficult for knowledge gained from especially small-scale experiments to be applicable to large-scale applications. Comparing the results from the larger and medium-sized trays, the use of medium-sized trays would be recommended in a facility over the use of larger trays that are more exposed to the ambient air.
In Chapter 6, an overall discussion of each experiment, implications of the results, limitations experienced, future directions and a final conclusion are presented. This work has added to and expanded on the scientific knowledge that is now available about H. illucens larvae and their use in bioconversion. This work builds on the current knowledge base of organic waste streams, and mixing of waste streams, with variable nutrient content and the experiments were conducted at an industrial scale, in a bioconversion facility, rather than a lab-scale study. As such, the results are more applicable to large-scale, commercial bioconversion operations and will provide some guidance on future large-scale rearing and processing experiments and application of that knowledge in industry.
There are several very complex interactions that occur during larval rearing; including substrate conditions like nutrients, microbes, moisture, pH and temperature, the ambient temperature and rates of substrate evaporation, larval density and age, and size and shape of the tray. Future work should consider these complex interactions to untangle and understand these complex interactions. Doing so will provide industry with recommendations for future best practicesSouth African Department of Trade and Industry through the Technology and Human Resource for Industry Programme (THRIP/51/30/11/2017)Zoology and EntomologyPhD (Applied Entomology)UnrestrictedFaculty of Natural and Agricultural SciencesSDG-06: Clean water and sanitationSDG-09: Industry, innovation and infrastructureSDG-12: Responsible consumption and productio
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
Olfactory preferences of gravid femaile stable flies Stomoxys calcitrans L. (Diptera : muscidae) and their fitness consequences
Get PDFThesis (PhD)--University of Pretoria, 2019.Oviposition decisions are a prominent example of behaviour directly affecting the fitness, abundance, distribution, and population dynamics of holometabolous insects. Due to eggs being immobile and adult insects often not practicing biparental and/or maternal care, gravid females, when ovipositing, should select substrate(s) that maximise fitness of their offspring. Studies have revealed that this selection is influenced by biotic (intra and interspecific competition, parasitism, larval experience, etc…) and abiotic (olfactory cues, visuals cues, substrate physiochemical properties, etc…) factors. However, in the stable fly, Stomoxys calcitrans L. (Diptera: Muscidae), a cosmopolitan blood-feeder that transmits several pathogens to animals, the influence of these factors in gravid female oviposition decisions is still unknown. Therefore, in this thesis, I examined oviposition decisions by S. calcitrans, associated fitness consequences for offspring, the olfactory cue(s) involved, and the influence of biotic factors in egg-laying decisions.
I demonstrated (Chapter 2) that S. calcitrans prefer to lay on donkey and sheep dung over camel, cow, elephant, giraffe, and zebra dung or grass. I showed that this preference was related to the good nutritional value of these substrates that consequently led to the best performance of S. calcitrans offspring. Furthermore, I identified β-citronellene and (R)-(-)-
carvone, from donkey and sheep dung, respectively, as the olfactory cues responsible for observed preference-performance behaviour. In the laboratory, β-citronellene and carvone elicited the strongest oviposition behaviour in S. calcitrans. I confirmed this in the field by showing that traps baited with these compounds also caught more gravid S. calcitrans.
To develop a better understanding of oviposition site selection in S. calcitrans, I went on to show (Chapter 3) that S. calcitrans avoided substrates with conspecific larvae, heterospecific (Musca domestica) larvae, or the mite, Macrocheles muscaedomesticae. This avoidance behaviour was associated with fitness costs to offspring incurred in the presence of competition and parasitism. Competition with conspecific larvae led to significant changes in wing morphology (Chapter 4), with flies reared in a group of 5 having larger wing centroid size, wing length, wing width, wing area and wing loading compared with those reared in a group of 25. Also, these parameters were higher in flies developed in donkey and sheep dung in comparison with those grown in camel and cow dung. Preferred dung may lead to adults with better dispersal capabilities. Larval experience does not affect oviposition decisions by female S. calcitrans because they did not prefer to oviposit on their developmental substrate. This ruled out the Hopkins’ host selection principle in S. calcitrans and verifies the importance of innate rather than learned oviposition preferences in this species.
Overall, the results reported in this thesis have enabled me to generate a fundamental knowledge of S. calcitrans oviposition decisions. Also, I have identified novel candidate attractants that could enhance trap catch of S. calcitrans to improve surveillance and limit transmission of pathogens. Furthermore, this thesis opens new research avenues in identifying repellents from conspecific and heterospecific larvae, which if packaged with the identified attractants could be used in a push-pull control system against S. calcitrans.Zoology and EntomologyPhDUnrestricte
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
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
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