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    Towards the Integrated Management of the Texas Citrus Mite Eutetranychus Banksi (Acari: Tetranychidae) in Spain

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    [ES] El ácaro de Texas, Eutetranychus banksi McGregor, es nativo de América y está ampliamente distribuido por el cultivo de cítricos de este continente. En 2013, esta especie se detectó en el sur de la provincia de Valencia, afectando a la principal zona citrícola de España. El ácaro produce graves daños reduciendo la fotosíntesis, causando defoliación y decoloración de los frutos, lo que podría afectar a su valor económico. En primer lugar, este trabajo evaluó el impacto ecológico producido por la especie invasora sobre las especies de ácaros tetraníquidos residentes en los cítricos valencianos Panonychus citri (McGregor) y Eutetranychus orientalis (Klein). Desde su llegada en 2013, E. banksi se ha convertido en el tetraníquido más frecuente y abundante en cítricos desplazando competitivamente a las otras especies, reduciendo su presencia y distribución geográfica, a su vez influenciada por su historia de colonización. En segundo lugar, este trabajo estudió la distribución dentro del árbol y las tendencias estacionales de la plaga y de los ácaros fitoseidos asociados, que pueden contribuir a su control. El ácaro de Texas se alimentó principalmente en la cara adaxial (haz) de las hojas en la periferia de la copa del árbol, mostrando un único pico de población a finales de verano-principios de otoño, mientras que los fitoseidos prefirieron la cara abaxial (envés) de las hojas del interior de la copa, mostrando dos picos, uno principal en primavera y otro menos abundante en otoño. Euseius stipulatus (Athias-Henriot) fue el fitoseido más frecuente y abundante, y cuando E. banksi aumentó se desplazó a las caras adaxiales de las hojas de la parte exterior de la copa y los frutos para alimentarse de su presa, cambiando su coloración de blanco a marrón rojizo evidenciando su contribución al control biológico de la plaga. Sin embargo, no fue capaz de mantener las poblaciones de E. banksi bajo densidades tolerables debido a la desfavorable relación depredador/presa que existe en verano y principios de otoño. En tercer lugar, este trabajo pretendió describir la estructura de población del ácaro de Texas y definir un plan de muestreo. Existieron diferencias en la estructura de edad en frutos y hojas, así como entre hojas de diferentes brotes. Además, a lo largo del tiempo se observaron fluctuaciones en su composición correlacionadas con variaciones en la proporción de sexos. No se observaron diferencias de agregación entre estratos vegetales, pero sí entre estadios inmaduros y adultos, siendo las hembras las menos agregadas. La alta correlación de la población total con las formas móviles y las hembras permitió utilizar ambas como estadio de referencia para el desarrollo del plan de muestreo, estableciendo un muestreo de presencia/ausencia de 100 hojas para las hembras o 400 hojas para las formas móviles. Finalmente, un ácaro fitoseido recientemente descrito, Neoseiulus madeirensis Papadoulis & Kapaxidi, se encontró asociado a E. banksi, sugiriendo que podría ser un candidato prometedor para su control biológico. En cuarto lugar, este trabajo pretendió evaluar el potencial de este depredador para controlar las poblaciones de la plaga. Neoseiulus madeirensis mostró un rápido desarrollo y altas tasas de supervivencia y reproducción alimentándose de E. banksi. El depredador se alimentó principalmente de estadios inmaduros, siendo los huevos el estadio preferido, y mostrando una respuesta funcional de tipo II para todos los estadios de presa ensayados, que se estabilizó a altas densidades de presa con una elevada puesta de huevos. Los valores de supervivencia, reproducción y depredación han sido los mejores obtenidos hasta el momento para cualquier fitoseido ensayado previamente contra E. banksi, lo convierte en un candidato idóneo para el desarrollo de un programa de control biológico basado en sueltas aumentativas, o en la importación con vistas al establecimiento de poblaciones permanentes en cítricos.[CA] L'àcar de Texas, Eutetranychus banksi McGregor, és nadiu d' Amèrica i està àmpliament distribuït pel cultiu de cítrics d'aquest continent. El 2013, esta espècie es va detectar al sud de la província de València, afectant la principal zona citrícola d'Espanya. L'àcar produeix greus danys reduint la fotosíntesi, causant defoliació i decoloració dels fruits, cosa que podria afectar el seu valor econòmic. En primer lloc, aquest treball va avaluar l'impacte ecològic produït per l'espècie invasora sobre les espècies d'àcars tetraníquids residents als cítrics valencians Panonychus citri (McGregor) i Eutetranychus orientalis (Klein). Des de la seva arribada el 2013, E. banksi s'ha convertit en el tetraníquid més freqüent i abundant en cítrics desplaçant competitivament les altres espècies, reduint la seva presència i distribució geogràfica, alhora influenciat per la seva història de colonització. En segon lloc, aquest treball va estudiar la distribució dins de l'arbre i les tendències estacionals de la plaga i dels àcars fitoseids associats, que poden contribuir al seu control. L'àcar de Texas es va alimentar principalment en la cara adaxial (fes) de les fulles a la perifèria de la copa de l'arbre, mostrant un únic pic de població a finals d'estiu-principis de tardor, mentre que els fitoseids van preferir la cara abaxial (revers) de les fulles de l'interior de la copa, mostrant dos pics, un de principal a la primavera i un altre menys abundant a la tardor. Euseius stipulatus (Athias-Henriot) va ser el fitoseid més freqüent i abundant, i quan E. banksi va augmentar es va desplaçar a les cares adaxials de les fulles de la part exterior de la copa i els fruits per alimentar-se de la presa, canviant la seva coloració de blanc a marró vermellós evidenciant la seva contribució al control biològic de la plaga. Tot i això, no va ser capaç de mantenir les poblacions d'E. banksi sota densitats tolerables a causa de la desfavorable relació depredador/presa que hi ha a l'estiu i principis de tardor. En tercer lloc, aquest treball va voler descriure l'estructura de població de l'àcar de Texas i definir un pla de mostreig. Hi hagué diferències en l'estructura d'edat de fruits i fulles, així com entre fulles de diferents brots. A més, al llarg del temps es van observar fluctuacions en la composició correlacionades amb variacions en la proporció de sexes. No es van observar diferències d'agregació entre estrats vegetals, però sí entre estadis immadurs i adults, sent les femelles les menys agregades. L'alta correlació de la població total amb les formes mòbils i les femelles va permetre utilitzar totes dues com a estadi de referència per al desenvolupament del pla de mostreig, establint un mostreig de presència/absència de 100 fulls per a les femelles o 400 fulls per a les formes mòbils. Finalment, una espècie fitoseid recentment descrit, Neoseiulus madeirensis Papadoulis & Kapaxidi, es va trobar associat a E. banksi, suggerint que podria ser un candidat prometedor per al seu control biològic. En quart lloc, aquest treball va voler avaluar el potencial d'aquest depredador per controlar les poblacions de la plaga. Neoseiulus madeirensis va mostrar un desenvolupament ràpid i altes taxes de supervivència i reproducció alimentant-se d'E. banksi. El depredador es va alimentar principalment d'estadis immadurs, sent els ous l'estadi preferit, i mostrant una resposta funcional de tipus II per a tots els estadis de presa assajats, que es va estabilitzar a altes densitats de presa amb una posta d'ous elevada. Els valors de supervivencia, depredació i reproducció han estat els millors obtinguts fins ara per a qualsevol espècie de fitoseid assajat prèviament contra E. banksi, cosa que el converteix en un candidat idoni per al desenvolupament d'un programa de control biològic basat en soltes augmentatives, o en la importació amb vista a l'establiment de poblacions permanents en cítrics.[EN] The Texas citrus mite, Eutetranychus banksi McGregor, is native to the Americas and widely distributed across this continent. In 2013 it was detected in the south of the province of Valencia, affecting the main citrus-growing area in Spain. The mite produces severe damage, reducing photosynthesis, causing defoliation, and producing a lack in fruit pigmentation, which could affect its economic value. Firstly, this work evaluated the ecological impact produced by the invasive species on the resident spider mites Panonychus citri (McGregor) and Eutetranychus orientalis (Klein). Since its arrival in 2013, E. banksi has become the most frequent and abundant spider mite on citrus, competitively displacing the other species and reducing their presence and geographic range, which is influenced by its colonisation history. Secondly, this work studies the within-tree distribution and seasonal trends of the pest and associated phytoseiid mites, which may contribute to its control. The Texas citrus mite was feeding mainly on the adaxial (upper) side of leaves in the periphery of the tree canopy showing a single population peak in late summer-early autumn, while phytoseiids preferred the abaxial (lower) sides inside the canopy showing two peaks, a main spring peak and a second, less abundant, in autumn. Euseius stipulatus (Athias-Henriot) was the most frequent and abundant phytoseiid, and when E. banksi increased, it moved to the adaxial sides on outer leaves and fruits to feed on its prey and changed its colouring from white to reddish-brown, evidencing its contribution to biological pest control. However, it was not capable of maintaining E. banksi populations under tolerable densities due to the unfavourable predator/prey ratios in summer and early autumn. Thirdly, this work aimed to describe the pest population structure and define a sampling plan. There were differences in the age structure on fruits and leaves, as well as between leaves from different flushes. Furthermore, over time, there were fluctuations in its composition correlated with variations in sex-ratio. No aggregation differences among plant strata were found, but there were significant differences between immature and adult stages, the females being the less aggregated. The high correlation of the total population with the motile forms and females allowed the use of both as a reference stage in the sampling plan, establishing a presence/absence sampling of 100 leaves for females or 400 leaves for motile forms. Finally, a recently described phytoseiid mite, Neoseiulus madeirensis Papadoulis & Kapaxidi, was found to be associated with E. banksi, suggesting that it could be a promising candidate for pest suppression. Fourthly, this work aimed to evaluate the potential of this predator to control pest populations. Neoseiulus madeirensis exhibited a short developmental time, high survival and reproductive rates feeding on E. banksi. The predator was fed mainly on immature stages, with eggs being the preferred stage, showing a type II functional response for all the prey stages tested, that stabilises at high prey densities with high egg laying. Survival, predation and reproduction values were the best obtained so far for any phytoseiid previously tested against E. banksi, making it a suitable candidate for the development of a biological control program based on augmentative releases, or importation aiming for the establishment of permanent populations on citrus.López Olmos, S. (2023). Towards the Integrated Management of the Texas Citrus Mite Eutetranychus Banksi (Acari: Tetranychidae) in Spain [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/20155

    Middle-Late Miocene palaeoceanographic development of Cyprus (E. Mediterranean) based on integrated study of δ¹⁸O and δ¹³C stable isotope records, supported by Mg/Ca palaeothermometry, nannofossil biostratigraphy, Sr isotopic dating, sedimentology and other geochemical data

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    Dynamic climate changes and regional tectonic convergence/collision were fundamental factors in the formation of earth, ocean and climate systems during the Middle to Late Miocene. CO2-driven global warming of the Miocene Climatic Optimum (MCO) has been proposed as an analogue for future anthropogenic climate change. However, the nature and extent of both the MCO and the subsequent Middle to Late Miocene cooling had remained poorly constrained in the eastern Mediterranean region. This region was affected by the closure of key ocean gateways, to the Indian Ocean during the Middle Miocene and to the Atlantic Ocean during the Late Miocene. The Late Miocene isolation of Mediterranean basins culminated in dramatic seawater salinity increase and extensive evaporite formation, known as the Messinian Salinity Crisis (MSC). The island of Cyprus exposes uplifted Cenozoic and Neogene deep-sea pelagic sedimentary rocks. These successions have not undergone deep burial diagenesis and can therefore be utilised to produce reliable geochemical records. The Lower to Upper Miocene succession at Kottaphi Hill and the Upper Miocene succession at Lapatza Hill were sampled in order to produce a composite stable isotope record (O and C), which spans the onset of the MCO to the onset of the MSC. The two successions were sampled at a vertical spacing of 5–25 cm and correlated using calcareous nannofossil biostratigraphy and stable isotope data, supported by field observations, X-ray diffraction and X-ray fluorescence data. Fine-fraction bulk rock and planktic foraminifera stable isotope records, together with trace element/Ca records, provide fresh insights into the evolution of sea surface temperature and ocean chemistry. The new data reveal how both global climate changes and the local to regional effects of ocean gateway closures affected Cyprus, and probably also the wider eastern Mediterranean during this time interval. The data also shed light on the sedimentary development related to the tectonic development of the adjacent Mesaoria Basin in Cyprus. In addition, strontium isotope dating of redeposited shallow-water carbonate material (e.g. bivalves) aids interpretation of contemporaneous Miocene reef-related facies elsewhere, in northwest Cyprus. This research demonstrates that pelagic carbonate successions such as at Kottaphi Hill can produce excellent stable isotopic records comparable to those for deep-sea cores, opening the way for comparable land-based isotopic studies elsewhere

    On the path integration system of insects: there and back again

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    Navigation is an essential capability of animate organisms and robots. Among animate organisms of particular interest are insects because they are capable of a variety of navigation competencies solving challenging problems with limited resources, thereby providing inspiration for robot navigation. Ants, bees and other insects are able to return to their nest using a navigation strategy known as path integration. During path integration, the animal maintains a running estimate of the distance and direction to its nest as it travels. This estimate, known as the `home vector', enables the animal to return to its nest. Path integration was the technique used by sea navigators to cross the open seas in the past. To perform path integration, both sailors and insects need access to two pieces of information, their direction and their speed of motion over time. Neurons encoding the heading and speed have been found to converge on a highly conserved region of the insect brain, the central complex. It is, therefore, believed that the central complex is key to the computations pertaining to path integration. However, several questions remain about the exact structure of the neuronal circuit that tracks the animal's heading, how it differs between insect species, and how the speed and direction are integrated into a home vector and maintained in memory. In this thesis, I have combined behavioural, anatomical, and physiological data with computational modelling and agent simulations to tackle these questions. Analysis of the internal compass circuit of two insect species with highly divergent ecologies, the fruit fly Drosophila melanogaster and the desert locust Schistocerca gregaria, revealed that despite 400 million years of evolutionary divergence, both species share a fundamentally common internal compass circuit that keeps track of the animal's heading. However, subtle differences in the neuronal morphologies result in distinct circuit dynamics adapted to the ecology of each species, thereby providing insights into how neural circuits evolved to accommodate species-specific behaviours. The fast-moving insects need to update their home vector memory continuously as they move, yet they can remember it for several hours. This conjunction of fast updating and long persistence of the home vector does not directly map to current short, mid, and long-term memory accounts. An extensive literature review revealed a lack of available memory models that could support the home vector memory requirements. A comparison of existing behavioural data with the homing behaviour of simulated robot agents illustrated that the prevalent hypothesis, which posits that the neural substrate of the path integration memory is a bump attractor network, is contradicted by behavioural evidence. An investigation of the type of memory utilised during path integration revealed that cold-induced anaesthesia disrupts the ability of ants to return to their nest, but it does not eliminate their ability to move in the correct homing direction. Using computational modelling and simulated agents, I argue that the best explanation for this phenomenon is not two separate memories differently affected by temperature but a shared memory that encodes both the direction and distance. The results presented in this thesis shed some more light on the labyrinth that researchers of animal navigation have been exploring in their attempts to unravel a few more rounds of Ariadne's thread back to its origin. The findings provide valuable insights into the path integration system of insects and inspiration for future memory research, advancing path integration techniques in robotics, and developing novel neuromorphic solutions to computational problems

    The use of proxies in designing for and with autistic children: supporting friendship as a case study

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    Participatory Design (PD) is an approach for designing new technologies which involves end users in the design process. It is generally accepted that involving users in the design process gives them a sense of ownership over the final product which enhances its usability and acceptance by the target population. Employing a PD approach can introduce multiple challenges especially when working with autistic children. Many approaches for involving autistic children and children with special needs were developed to address these challenges. However, these frameworks introduce their own limitations as well. There is an ethical dilemma to consider in the involvement of autistic children in the design process. Although we established the ethical benefit of involving children, we did not address the ethical issues that will result from involving them in these research projects. Among other issues, the nature of design workshops we as a community currently run require working with unfamiliar researchers and communicating with them while social and communication differences are one of the main diagnostic criteria for autism. When designing for autistic children and other vulnerable populations an alternative (or most often an additional) approach is designing with proxies. Proxies for the child can be one of several groups of other stakeholders, such as: teachers, parents and siblings. Each of these groups may inform the design process, from their particular perspective, and as proxies for the target group of autistic children. Decisions need to be made about what stages in the design process are suited to their participation, and the role they play in each case. For this reason, we explore the role of teachers, parents, autistic adults and neurotypical children as proxies in the design process. To explore the roles of proxies we chose friendship between autistic and neurotypical children as the context we are designing for. We are interested in understanding the nature of children's friendships and the potential for technology to support them. Although children themselves are the ones who experience friendship and challenges around its development and peer interaction, they might find it difficult to articulate the challenges they face. Furthermore, it is unrealistic to expect children to identify strategies to help them overcome the challenges with friendship development that they are facing as it assumes children have the social skills to come up with these strategies in the first place. Hence, it is necessary in this context to consider proxies who can identify challenges and suggest ways to overcome them

    An investigation into the environmental sustainability of the South African ornamental horticultural industry

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    The ornamental horticultural industry makes use of natural resources to grow plants and produce allied products to sell to consumers, landscapers, retail garden centres, hardware stores, supermarkets, and government, but at what cost to the environment? The aim of this work was to determine the current environmental awareness of growers and garden centre retailers within the ornamental horticultural industry in South Africa. Followed by an investigation into the current business practices that promote sustainable natural resource use and management as well as the obstacles and challenges that the industry faces with implementing legislation and recommendations of best practices. The study was conducted over an 18-month period and 41 growers and retail garden centres in eight of the provinces in South Africa (Appendix 10) participated in research. In each case, the study participant was asked to complete the questionnaire and where possible, a site visit was conducted and / or a semi-structured interview as well as participatory observations followed to give a comprehensive overview of the sustainability practices of the businesses. These results were then compared to international best practices and similar research conducted globally by the ornamental horticultural industry. A review of international best practices in the ornamental horticultural industry showed six environmental resources namely soil, water, fertilizers, pesticides, energy, and waste. This was seen to be common to most studies involved in the production, growth, maintenance and sales of plants and allied products. This information was used to compile a best management practice manual for South African ornamental horticulture with guidelines and practical examples for conserving and managing natural resource usage and reducing the environmental impacts of the industry. Much research has been done on the exploitation and degradation of resources due to urbanisation, industrial activities, and agricultural practices. The resources are essential to the ornamental horticultural industry but if exploited or misused, can have detrimental effects on the environmental productivity of the industry and ultimately the “Sustainable Development Goals” prescribed by the United Nations. The linking of the relevant sustainable development goals to the 9 key factors of the green economy strategized by the South African government will enable the ornamental horticultural industry to play a greater part in the green and circular economy by providing nature-based solutions to environmental problems that it is facing such as climate change and pollution.Environmental SciencesD. Phil. (Environmental Management

    Petrology and geochemistry of peri-Mediterranean carbonatite magmatism: case studies from Fuerteventura (Canary Islands) and Mt. Vulture volcano (southern Italy)

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    Carbonatites are rare magmatic rocks of great scientific and economic importance, and carbonatite magmatism is mainly associated with intraplate continental tectonic settings, with some rare occurrences in oceanic contexts. Despite their importance, many aspects of carbonatite petrogenesis and evolution processes remain still poorly constrained. In order to further constrain the mantle source and the storage system of carbonatite magmas, Fuerteventura (Canary Islands) was taken as a representative case study of oceanic carbonatites, while Mt. Vulture (southern Italy) was taken as a representative case study of intra-continental carbonatites, with a two-fold aim: to understand (i) the role of the carbonatite primary melts in metasomatizing the mantle source in different geodynamic settings with possible implications in terms of volcanic hazard, and (ii) the role of the infiltrating fluids in the transport and concentration of Rare Earth Elements (REEs) with the processes involved in the carbonatite-related hydrothermal mineralization. The first noble gases study on intrusive oceanic Ca-carbonatites from Fuerteventura reflects a sub-continental lithospheric mantle (SCLM) signature in their petrogenesis, corroborating that, also in the rare context of oceanic lithosphere, a contribute of a sub-continental lithosphere is needed. As regards the REEs characterization, detailed petrographic and micro-thermometric studies on the same carbonatites show how REEs can be mobilised locally by low-temperature hydrothermal fluids with a process known as autometasomatism (for intrusive carbonatites). At sub-solidus temperatures (T > 600 °C) and the brine-melt stage (600 ≤ T ≤ 400 °C), where REEs are sufficiently concentrated in the residual brine-melt to form REE-minerals, the infiltrating fluids play an important role in the transport and concentration of REEs, as testified by the presence of REEs-rich filled microfractures in accessory minerals. As regards the Mt. Vulture case study, a suite of several pelletal lapilli (enclosing ultramafic mantle xenoliths), mantle xenoliths and loose olivine and clinopyroxene xenocrysts, brought to the surface by the last melilitite-carbonatite explosive volcano activity, was characterized. The melilitite-carbonatite matrix and carbonatite-rich layers within the matrix in the ash-rich tuff deposits, show whole rock compositions comparable with those of the average values of extrusive carbonatites, suggesting a possible contribution of a carbonatite melt in the trace elements enrichment processes. Furthermore, petrographic evidences of wehrlitization processes reflects the direct evidence of carbonatite metasomatism beneath the Mt. Vulture. Detailed petrographic, micro-thermometric, and geothermometric studies provide insights into the P-T history of the mineral-melt-fluid interaction processes in the mantle and within the Mt. Vulture magma storage system, identifying evidences of wehrlitization processes and two different magma ponding stages at the local crust-mantle boundary and at a shallower crustal level. Calculations on magma dynamics show how the ascent rates of carbonatite magmas can be comparable with kimberlite magmas, with the important role of a pure CO2 gas phase as principal propellent in an upward moving elutriated gas-dominated medium. High calculated oxygen fugacity supports the geochemical evidence that Mt. Vulture xenoliths would have formed by interaction with an oxidized CO2-rich metasomatic fluid, according to the presence of pure CO2 fluid inclusions within the mantle xenoliths-forming minerals

    GAC-MAC-SGA 2023 Sudbury Meeting: Abstracts, Volume 46

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