Tesi sul tema "Ants"

The focus of this thesis paper is to study the impact the number of ants has on the found solution of the Ant Colony Optimization (ACO) metaheuristic when solving the Traveling Salesman Problem. The goal was to find out how the length of the computed tours change for different amounts of ants within a limited number of iterations. To study this, three well known versions of the ACO algorithm were implemented and tested: Min-Max Ant System (MMAS), Elitist Ant System (EliteAS) and Ranked Ant System (RankedAS). The results showed trends that were consistent over several test cases. EliteAS and RankedAS which both utilize specialist ants showed clear signs that the number of specialists had a large influence on the length of solutions. Meanwhile, normal ants did not affect the solutions as much. MMAS and EliteAS only had a small variation on the answer, with lower amount of ants being more favorable. On the other hand, RankedAS performed better by a large margin when working with five specialists and a number of ants equaling the number of cities in the problem.<br>Målet med denna rapport var att studera hur antalet myror som används av Ant Colony Optimization (ACO) påverkar resultatet vid lö- sandet av Traveling Salesman Problem (TSP). Hur ändras lösningens längd med olika antal myror, när antalet iterationer som får användas är begränsat? För att få fram ett svar på frågan implementerades och testades tre välkända ACO algoritmer: Min-Max Ant System (MMAS), Elitist Ant System (EliteAS) och Ranked Ant System (RankedAS). Efter implementering och utförlig testning så uppdagades trender som var konsistenta över flera testfall. För EliteAS och RankedAS, som bå- da förlitar sig på specialiserade myror, hade antalet specialister en stor påverkan på den funna längden. Normala myror hade istället en liten påverkan på slutresultatet. För MMAS och EliteAS så var skillnaden minimal, med en viss favör mot ett lägre antal myror. RankedAS hade en motsatt trend och hade bäst resultat med fem specialister och lika många normala myror som antalet städer i TSP instansen.

Loss is a fundamental part of the human experience, from the loss of security and innocence that comes with the necessary separation of child from parent to the ultimate loss of life. Along the way, there are the losses of jobs, of incomes, of homes; the losses of friendships, of family members, of lovers; the losses of direction, of control, of hope. As cognitive and caring beings, humans struggle to cope with these losses, to greater and lesser degrees of success. This is the theme at the heart of this thesis. Fire Ants is composed of ten short stories, fictive works, which differ in specific subject matter, yet deal unilaterally with issues of loss. Like the venomous creatures that threaten to eat B. D. Packard alive in the title story, life eats away at a number of characters in the collection who are deficient. The narrators in "Aftermath" and "Hues," for example, suffer psychological -- if not physical -- deaths. But not all of the characters lack coping mechanisms, unhealthy as they may sometimes be. As the stories unfold, some characters begin to gain small degrees of perspective and understanding, to learn that while life is full of loss, it is not always entirely bleak. As demonstrated in "Cross Creek," good exists, though it is not always where one might expect it. And life can be full despite loss, as depicted in "Stitches."

Les remarquables capacités de navigation des insectes nous prouvent à quel point ces " mini-cerveaux " peuvent produire des comportements admirablement robustes et efficaces dans des environnements complexes. En effet, être capable de naviguer de façon efficace et autonome dans un environnement parfois hostile (désert, forêt tropicale) sollicite l'intervention de nombreux processus cognitifs impliquant l'extraction, la mémorisation et le traitement de l'information spatiale préalables à une prise de décision locomotrice orientée dans l'espace. Lors de leurs excursions hors du nid, les insectes tels que les abeilles, guêpes ou fourmis, se fient à un processus d'intégration du trajet, mais également à des indices visuels qui leur permettent de mémoriser des routes et de retrouver certains sites alimentaires familiers et leur nid. L'étude des mécanismes d'intégration du trajet a fait l'objet de nombreux travaux, par contre, nos connaissances à propos de l'utilisation d'indices visuels sont beaucoup plus limitées et proviennent principalement d'études menées dans des environnements artificiellement simplifiés, dont les conclusions sont parfois difficilement transposables aux conditions naturelles. Cette thèse propose une approche intégrative, combinant 1- des études de terrains et de laboratoire conduites sur deux espèces de fourmis spécialistes de la navigation visuelle (Melophorus bagoti et Gigantiops destructor) et 2- des analyses de photos panoramiques prisent aux endroits où les fourmis naviguent qui permettent de quantifier objectivement l'information visuelle accessible à l'insecte. Les résultats convergents obtenus sur le terrain et au laboratoire permettent de montrer que, chez ces deux espèces, les fourmis ne fragmentent pas leur monde visuel en multiples objets indépendants, et donc ne mémorisent pas de 'repères visuels' ou de balises particuliers comme le ferait un être humain. En fait, l'efficacité de leur navigation émergerait de l'utilisation de paramètres visuels étendus sur l'ensemble de leur champ visuel panoramique, incluant repères proximaux comme distaux, sans les individualiser. Contre-intuitivement, de telles images panoramiques, même à basse résolution, fournissent une information spatiale précise et non ambiguë dans les environnements naturels. Plutôt qu'une focalisation sur des repères isolés, l'utilisation de vues dans leur globalité semble être plus efficace pour représenter la complexité des scènes naturelles et être mieux adaptée à la basse résolution du système visuel des insectes. Les photos panoramiques enregistrées peuvent également servir à l'élaboration de modèles navigationnels. Les prédictions de ces modèles sont ici directement comparées au comportement des fourmis, permettant ainsi de tester et d'améliorer les différentes hypothèses envisagées. Cette approche m'a conduit à la conclusion selon laquelle les fourmis utilisent leurs vues panoramiques de façons différentes suivant qu'elles se déplacent en terrain familier ou non. Par exemple, aligner son corps de manière à ce que la vue perçue reproduise au mieux l'information mémorisée est une stratégie très efficace pour naviguer le long d'une route bien connue ; mais n'est d'aucune efficacité si l'insecte se retrouve en territoire nouveau, écarté du chemin familier. Dans ces cas critiques, les fourmis semblent recourir à une seconde stratégie qui consiste à se déplacer vers les régions présentant une ligne d'horizon plus basse que celle mémorisée, ce qui généralement conduit vers le terrain familier. Afin de choisir parmi ces deux différentes stratégies, les fourmis semblent tout simplement se fier au degré de familiarisation avec le panorama perçu. Cette thèse soulève aussi la question de la nature de l'information visuelle mémorisée par les insectes. Le modèle du " snapshot " qui prédomine dans la littérature suppose que les fourmis mémorisent une séquence d'instantanés photographiques placés à différents points le long de leurs routes. A l'inverse, les résultats obtenus dans le présent travail montrent que l'information visuelle mémorisée au bout d'une route (15 mètres) modifie l'information mémorisée à l'autre extrémité de cette même route, ce qui suggère que la connaissance visuelle de l'ensemble de la route soit compactée en une seule et même représentation mémorisée. Cette hypothèse s'accorde aussi avec d'autres de nos résultats montrant que la mémoire visuelle ne s'acquiert pas instantanément, mais se développe et s'affine avec l'expérience répétée. Lorsqu'une fourmi navigue le long de sa route, ses récepteurs visuels sont stimulés de façon continue par une scène évoluant doucement et régulièrement au fur et à mesure du déplacement. Mémoriser un pattern général de stimulations, plutôt qu'une série de " snapshots " indépendants et très ressemblants les uns aux autres, constitue une hypothèse parcimonieuse. Cette hypothèse s'applique en outre particulièrement bien aux modèles en réseaux de neurones, suggérant sa pertinence biologique. Dans l'ensemble, cette thèse s'intéresse à la nature des perceptions et de la mémoire visuelle des fourmis, ainsi qu'à la manière dont elles sont intégrées et traitées afin de produire une réponse navigationnelle appropriée. Nos résultats sont aussi discutés dans le cadre de la cognition comparée. Insectes comme vertébrés ont résolu le même problème qui consiste à naviguer de façon efficace sur terre. A la lumière de la théorie de l'évolution de Darwin, il n'y a 'a priori' aucune raison de penser qu'il existe une forme de transition brutale entre les mécanismes cognitifs des différentes espèces animales. Le fossé marqué entre insectes et vertébrés au sein des sciences cognitives pourrait bien être dû à des approches différentes plutôt qu'à de vraies différences ontologiques. Historiquement, l'étude de la navigation de l'insecte a suivi une approche de type 'bottom-up' qui recherche comment des comportements apparemment complexes peuvent découler de mécanismes simples. Ces solutions parcimonieuses, comme celles explorées dans cette thèse, peuvent fournir de remarquables hypothèses de base pour expliquer la navigation chez d'autres espèces animales aux cerveaux et comportements apparemment plus complexes, contribuant ainsi à une véritable cognition comparée<br>Navigating efficiently in the outside world requires many cognitive abilities like extracting, memorising, and processing information. The remarkable navigational abilities of insects are an existence proof of how small brains can produce exquisitely efficient, robust behaviour in complex environments. During their foraging trips, insects, like ants or bees, are known to rely on both path integration and learnt visual cues to recapitulate a route or reach familiar places like the nest. The strategy of path integration is well understood, but much less is known about how insects acquire and use visual information. Field studies give good descriptions of visually guided routes, but our understanding of the underlying mechanisms comes mainly from simplified laboratory conditions using artificial, geometrically simple landmarks. My thesis proposes an integrative approach that combines 1- field and lab experiments on two visually guided ant species (Melophorus bagoti and Gigantiops destructor) and 2- an analysis of panoramic pictures recorded along the animal's route. The use of panoramic pictures allows an objective quantification of the visual information available to the animal. Results from both species, in the lab and the field, converged, showing that ants do not segregate their visual world into objects, such as landmarks or discrete features, as a human observers might assume. Instead, efficient navigation seems to arise from the use of cues widespread on the ants' panoramic visual field, encompassing both proximal and distal objects together. Such relatively unprocessed panoramic views, even at low resolution, provide remarkably unambiguous spatial information in natural environment. Using such a simple but efficient panoramic visual input, rather than focusing on isolated landmarks, seems an appropriate strategy to cope with the complexity of natural scenes and the poor resolution of insects' eyes. Also, panoramic pictures can serve as a basis for running analytical models of navigation. The predictions of these models can be directly compared with the actual behaviour of real ants, allowing the iterative tuning and testing of different hypotheses. This integrative approach led me to the conclusion that ants do not rely on a single navigational technique, but might switch between strategies according to whether they are on or off their familiar terrain. For example, ants can recapitulate robustly a familiar route by simply aligning their body in a way that the current view matches best their memory. However, this strategy becomes ineffective when displaced away from the familiar route. In such a case, ants appear to head instead towards the regions where the skyline appears lower than the height recorded in their memory, which generally leads them closer to a familiar location. How ants choose between strategies at a given time might be simply based on the degree of familiarity of the panoramic scene currently perceived. Finally, this thesis raises questions about the nature of ant memories. Past studies proposed that ants memorise a succession of discrete 2D 'snapshots' of their surroundings. Contrastingly, results obtained here show that knowledge from the end of a foraging route (15 m) impacts strongly on the behaviour at the beginning of the route, suggesting that the visual knowledge of a whole foraging route may be compacted into a single holistic memory. Accordingly, repetitive training on the exact same route clearly affects the ants' behaviour, suggesting that the memorised information is processed and not 'obtained at once'. While navigating along their familiar route, ants' visual system is continually stimulated by a slowly evolving scene, and learning a general pattern of stimulation rather than storing independent but very similar snapshots appears a reasonable hypothesis to explain navigation on a natural scale; such learning works remarkably well with neural networks. Nonetheless, what the precise nature of ants' visual memories is and how elaborated they are remain wide open question. Overall, my thesis tackles the nature of ants' perception and memory as well as how both are processed together to output an appropriate navigational response. These results are discussed in the light of comparative cognition. Both vertebrates and insects have resolved the same problem of navigating efficiently in the world. In light of Darwin's theory of evolution, there is no a priori reason to think that there is a clear division between cognitive mechanisms of different species. The actual gap between insect and vertebrate cognitive sciences may result more from different approaches rather than real differences. Research on insect navigation has been approached with a bottom-up philosophy, one that examines how simple mechanisms can produce seemingly complex behaviour. Such parsimonious solutions, like the ones explored in the present thesis, can provide useful baseline hypotheses for navigation in other larger-brained animals, and thus contribute to a more truly comparative cognition

This thesis is prepared in three parts; the first part is a study of the ant species of the southern Carnarvon Basin, which was undertaken in order to determine the patterns of ant species distribution in this arid zone area. The distribution patterns were looked at in terms of biogeographical regions and they demonstrated the transitional nature of this particular area. Recommendations to alter the border between the South-west Province and the Eremaean Province were supported. The next chapter of this thesis analysed ant species from long unburnt and burnt areas of three main vegetation types (two Triodia species grasslands and Acacia aneura woodlands) in the Gibson Desert Nature Reserve. This study was carried out to observe the recovery of ant populations after fire. The results provided further evidence that invertebrates are measurably impacted by fire in the arid zone. The final chapter is a comparison of these two arid zone studies with six other ant community studies from throughout Western Australia. It demonstrated the uniqueness of some arid zone sites as well as related each study to each other according to their ant communities.

In social insects, foraging is often cooperative, and so requires considerable organisation. In most ants, organisation is a bottom-up process where decisions taken by individuals result in emergent colony level patterns. Individuals base their decisions on their internal state, their past experience, and their environment. By depositing trail pheromones, for example, ants can alter the environment, and thus affect the behaviour of their nestmates. The development of emergent patterns depends on both how individuals affect the environment, and how they react to changes in the environment. Chapters 4 – 9 investigate the role of trail pheromones and route memory in the ant Lasius niger. Route memories can form rapidly and be followed accurately, and when route memories and trail pheromones contradict each other, ants overwhelmingly follow route memories (chapter 4). Route memories and trail pheromones can also interact synergistically, allowing ants to forage faster without sacrificing accuracy (chapter 5). Home range markings also interact with other information sources to affect ant behaviour (chapter 6). Trail pheromones assist experienced ants when facing complex, difficult-to-learn routes (chapter 7). When facing complicated routes, ants deposit more pheromone to assist in navigation and learning (chapter 7). Deposition of trail pheromones is suppressed by ants leaving a marked path (chapter 5), strong pheromone trails (chapter 7) and trail crowding (chapter 8). Colony level ‘decisions' can be driven by factors other than trail pheromones, such as overcrowding at a food source (chapter 9). Chapter 10 reviews the many roles of trail pheromones in ants. Chapters 11 – 14 focus on the organisation of cooperative food retrieval. Pheidole oxyops workers arrange themselves non-randomly around items to increase transport speeds (chapter 11). Groups of ants will rotate food items to reduce drag (chapter 12). Chapters 13 and 14 encompass the ecology of cooperative transport, and how it has shaped trail pheromone recruitment in P. oxyops and Paratrechina longicornis. Lastly, chapter 15 provide a comprehensive review of cooperative transport in ants and elsewhere.

Group living is a widely adopted strategy by many organisms and given the advantages offered by a social lifestyle, such as increased protection from predators or increased ability for resource exploitation, a wide variety of animals have adopted a social lifestyle. Arguably none have done this more successfully than the social insects. Indeed their efficient division of labour is often cited as a key attribute for the remarkable ecological and evolutionary success of these societies. Within the social insects the most obvious division of labour is reproductive, in which one or a few individuals monopolise reproduction while the majority of essentially sterile workers carry out the remaining tasks essential for colony survival. In almost all social insects, in particular ants, the age of a worker will predispose it to certain tasks, and in some social insects the workers vary in size such that task is associated with worker morphology. In this thesis I explore the proximate and ultimate causes of worker and reproductive division of labour in ant societies, which span a range of social complexities. I predominantly focus on both the highly derived leaf-cutting ants – a so-called ‘pinnacle' of evolution within the social insects, with a complex division of labour and a strong worker caste system – and in the more basal primitive societies of the queenless ponerine dinosaur ants, which can offer an insight in to the evolution of division of labour at the earliest stages of social lifestyles. This work demonstrates the environmental and genetic determinants of division of labour in group-living societies outside of the classical honey bee model system. This is important as it helps us to better understand the broader processes shaping behaviour and phenotype in the animal kingdom.

Thesis (M.S.)--Florida State University, 2004.<br>Advisor: Dr. Walter R. Tschinkel, Florida State University, College of Arts and Sciences, Dept. of Biological Science. Title and description from dissertation home page (viewed Sept. 24, 2004). Includes bibliographical references.

Boston University. University Professors Program Senior theses.<br>PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.<br>2031-01-02

The importance of ants as elements in cave ecology has been mostly unrecognized. A global list of ant species recorded from caves, compiled from a review of existing literature, is presented. This paper also reviews what is currently known about ants occurring in Arizona ( USA) caves. The diversity and distribution represented in these records suggests ants are relatively common cave visitors (trogloxenes). A general utilization of caves by ants within both temperate and tropical latitudes may be inferred from this combined evidence. Observations of ant behavior in Arizona caves demonstrate a low level and sporadic, but persistent, use of these habitats and their contained resources by individual ant colonies. Documentation of Neivamyrmex sp. preying on cave-inhabiting arthropods is reported here for the first time. Observations of hypogeic army ants in caves suggests they may not penetrate to great vertical depth in search of prey, but can be persistent occupants in relatively shallow, horizontal sections of caves where they may prey on endemic cave animals. First cave records for ten ant species are reported from Arizona caves. These include two species of Neivamyrmex (N. nigrescens Cresson and Neivamyrmex sp.; Formicidae: Dorylinae), four myrmicines (Pheidole portalensis Wilson, Pheidole cf. porcula Wheeler, Solenopsis aurea Wheeler and Stenamma sp. Westwood), one dolichoderine (Forelius keiferi Wheeler) and three formicines (Lasius arizonicus Wheeler, L. sitiens Wilson, and Camponotus sp. Mayr).

Orientador: Odair Correa Bueno<br>Banca: Luiz Carlos Forti<br>Banca: Maria Santina de Castro Morini<br>Banca: Osmar Malaspina<br>Banca: Ana Eugênia de Carvalho Campos Farinha<br>Abstract: The present work aimed to evaluate the efficiency of crude oils of Carapa guianensis Aubl. (crabwood), Elaeis guineensis Jacq. (African oil palm), Sesamum indicum L. (sesame), Ricinus communis L. (castor beans), Azadirachta indica Juss (neem), Theobroma cacao L. (cocoa), Anacardium occidentale L. (cashew nut) and crude extracts of Anacardium occidentale on leafcutting ants control, using Atta sexdens rubropilosa as model. Toxicity bioassays with ant workers were done using: 1) treatments by incorporation of crude oils or extracts in artificial diet and 2) treatments by topic application of crude oils or extracts on the ants pronotum. According to obtained results in toxicity tests, some crude oils and extracts were select to be incorporated in baits or applied by nebulization and tested on laboratory colonies. The crude oils or extracts more efficient on laboratory colonies control were tested on field grown up colonies. The obtained results in all toxicity tests permitted to select crude oils of C. guianensis, E. guineensis, S. indicum, R. communis, A. indica, A. occidentale and hexane, dichloromethane, ethyl acetate and methanol extracts of A. occidentale to be applied by nebulization and crude oils of E. guineensis, A. indica and A. occidentale to be incorporated in baits and tested on laboratory colonies. On laboratory colonies, the nebulization with crude oils of C. guianensis, E. guineensis, S. indicum, R. communis and A. indica didn't cause any effect on colonies. Therefore, these crude oils don't must be used to leaf-cutting ants control. However, crude oil and hexane, dichloromethane, ethyl acetate and methanol extracts of A. occidentale propitiated the extinction of colonies. The E. guineensis, A. indica and A. occidentale baits didn't any cause effect on colonies hence it follows that these baits don't must be used to leaf-cutting ant's control<br>Doutor

Orientador: Odair Correa Bueno<br>Banca: Luiz Carlos Forti<br>Banca: Ana Paula Protti de Andrade Crusciol<br>Banca: Maria Santina de Castro Morini<br>Banca: Sulene Noriko Shima<br>Resumo: O presente trabalho teve como objetivo o estudo da evolução dos comportamentos de preparação do substrato, cuidado com a cria e cuidado com a rainha e alados em formigas cultivadoras de fungo. Estas formigas pertencem à tribo Attini, subfamília Myrmicinae, e ocorrem exclusivamente no continente americano. Esta tribo contém aproximadamente 230 espécies, porém pouco se conhece da biologia da maioria delas, graças ao fato de serem extremamente crípticas e de não apresentarem importância econômica, como as formigas cortadeiras, que são as mais estudadas. Foram utilizadas seis espécies, que representam bem os diversos níveis da filogenia da tribo: Acromyrmex disciger, Apterostigma pilosum, Mycetarotes parallelus, Myrmicocrypta sp., Trachymyrmex fuscus e Trachymyrmex sp. nov. Os comportamentos foram estudados em ninhos mantidos em laboratório, com o auxílio de micro-câmeras e um aparelho gravador de vídeo. Os comportamentos foram analisados, caracterizados e quantificados. Os resultados foram divididos em três capítulos de acordo com o tipo de comportamento. No capítulo sobre a evolução dos comportamentos de preparação do substrato foi observado que, basicamente, o processo evoluiu no sentido de aumentar a capacidade das operárias em decompor inicialmente o substrato. As espécies basais, A. pilosum, M. parallelus e Myrmicocrypta sp. apresentaram um processamento mais simples com um número menor de comportamentos e principalmente sem os comportamentos do tratamento químico, que é responsável pela fragmentação do substrato ao mesmo tempo em que ele é tratado com enzimas digestivas. As duas espécies do gênero Trachymyrmex apresentaram um processo mais complexo com grande participação do tratamento químico. Em A. disciger, que é uma cortadeira, há uma intensa especialização do sistema de castas para o aumento da eficiência... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: This work aims to study the evolution of the behaviors of substrate preparation, brood, queen and winged forms care in fungus growing ants. These ants are included in the tribe Attini, subfamily Myrmicinae, and occur exclusively in the american continent. This tribe contains approximately 230 species, but little is known about the biology of most of them, tanks to the fact that they show very cryptic habits and are not economically important, like the leaf cutting ants, which are the most studied. Six species were used in this work, which represent well all the levels of the phylogeny of the tribe: Acromyrmex disciger, Apterostigma pilosum, Mycetarotes parallelus, Myrmicocrypta sp., Trachymyrmex fuscus and Trachymyrmex sp. Nov. The behaviors were studied in laboratory nests, with a set of micro cameras and a video recording device. The behaviors were analyzed, characterized and quantified. The results were summarized and discussed in tree chapters, arranged by type of behavior. In the chapter about the evolution of the substrate preparation behaviors, basically it is assumed that this process evolved in order to develop the capacity of previously decompose the substrate by the workers. In the basal species, A. pilosum, M. parallelus and Myrmicocrypta sp. this process is very simple with a small number of behaviors and principally without the behaviors of chemical treatment, which are responsible for the fragmentation of the substrate as it is treated by with digestive enzymes. In the two species of the genus Trachymyrmex, the process became more complex and showed a greater participation of these behaviors. A. disciger, witch is a leaf cutting ant, showed an extensive specialization of physical castes in all the phases of the process which elevated it's efficiency. In the chapter about the evolution of the behaviors of brood care... (Complete abstract click electronic access below)<br>Doutor

This thesis is prepared in three parts; the first part is a study of the ant species of the southern Carnarvon Basin, which was undertaken in order to determine the patterns of ant species distribution in this arid zone area. The distribution patterns were looked at in terms of biogeographical regions and they demonstrated the transitional nature of this particular area. Recommendations to alter the border between the South-west Province and the Eremaean Province were supported. The next chapter of this thesis analysed ant species from long unburnt and burnt areas of three main vegetation types (two Triodia species grasslands and Acacia aneura woodlands) in the Gibson Desert Nature Reserve. This study was carried out to observe the recovery of ant populations after fire. The results provided further evidence that invertebrates are measurably impacted by fire in the arid zone. The final chapter is a comparison of these two arid zone studies with six other ant community studies from throughout Western Australia. It demonstrated the uniqueness of some arid zone sites as well as related each study to each other according to their ant communities.

<p>Living in Information Society, we always want to improve the networks to get more reliability, more bit rate, less “ping”. CE ant Layer 2 systems appear in order to change the concept of usual centralized networks, where the control is centralized and paths are decided before to start the transmission (with the consequent impossibility of balance the load). Layer 2 networks provide fast forwarding of packets from one link to another, without checking IP direction and avoiding to use some error corrections (like in Layer 3 networks), so they do not spend time in too much things, this is the reason because we use Layer 2 networks. The main aim for this work has been to study CE ant systems in Layer 2 networks and ameliorate the behaviours that can be improved by simulations of previous theoretical study. After 4 proposals studied, two of them have been discarded and other two have been confirmed as improvements. These improvements let us to use two different cost functions (for different environments of the network) in order to decide the optimal path.</p>

Social Hymenopterans such as bees, wasps and ants have developed sophisticated and effective communication among nestmates. Their remarkable ability to perform certain task such as in navigation suggests that these animals are able to learn and process the information they have gathered. Here, I test for such abilities in tandem running recruitment whereby an informed ant leads a na'ive ant to a resource and tactile cues are used by the follower ants to prompt the leader ants to move forward after a pause. The experiments presented here show that in addition to tactile signals being used, chemical signals are also being laid on the substrate by the leader ants mainly to maintain the bond between the tandem run pairs until they reach the goal. Both leader and follower ants learn visual cues during tandem running. The ants learn landmarks as well as the position of parallel wall edges and use this information to guide them in navigation to and from their nest. Furthermore, this information is updated on subsequent journeys making experienced ants better at navigation than newly recruited ants. Finally, I show that when communication between tandem running ants is manipulated experimentally by a dummy leader, many followers are not able to return to their old nest after having been led much quicker than the normal speed of tandem running. I hypothesize that this is due to the lack of learning opportunities and information gathering by the follower ants during such experimentally manipulated tandem running. Overall, my results strongly suggest that the navigational strategies of tandem running ants involve cognitive abilities. Ants, despite having small brains, are able to learn and process the information they gather to help them navigate efficiently in unpredictable environmental conditions.

Thesis (MSc)--Stellenbosch University, 2013.<br>Ants emerged during the Cretaceous Period more than 100 million years ago (Grimaldi & Engel 2005; Perrichot et al. 2008) and diversified independently on different landmasses following the Early Cretaceous fragmentation of Pangaea (Grimaldi & Agosti 2000). Today, ants represent one of the most ecologically successful groups globally (Wilson 1987), and their diversity far exceeds that of other social insects (Hölldobler & Wilson 1990). Currently 21 subfamilies, 305 genera and 12465 recorded ant species exist (Bolton 2012). Ants occur in almost all terrestrial habitats (Brown 2000) and are not uniformly distributed across regions, biomes and continents. As with all other taxa, historical abiotic factors have played a major role in their diversification and biogeographic structure (Tolley et al. 2006), including climatic changes (Holldobler & Wilson 1990) and the necessity to adapt to new environmental conditions (Tolley et al. 2006). Many global areas still lack data on regional biodiversity and the historical processes that may have shaped it. This is particularly so for southern Africa where the ant fauna is still relatively poorly known (Robertson 2000) and where there have been no published biogeographic analyses for any ant taxon. There is a highly endemic ant fauna that has evolved in the dry regions of southern Africa, which shows unique adaptations to the extreme thermal niches of these regions. For example, ants in the genus Ocymyrmex have adapted to forage on barren ground at temperatures as high as 67 ºC, when most insects and other arthropods are unable to survive (Marsh 1985). Ocymyrmex have long legs and usually hold the head, thorax and gaster high above the substrate, which helps with body temperature regulation. These ants are most active at the hottest time of the day and they move very rapidly. For example, O. barbiger has been observed running at speeds of 23 m/min (Marsh, 1985). In some ant species such extreme temperatures may limit foraging activity (Ward, 2007) but, in the case of Ocymyrmex, adaptations to this extreme thermal niche allowed exploitation of resources (dead and heat stressed arthropods). Moreover, these ants have subterranean nests that are ideal to escape environmental extremes and to move their brood deeply under the ground (Marsh, 1985). The distribution of some ant taxa in these dry regions closely reflects borders between particular biomes. For instance, in South Africa the ponerine ant, Pachycondyla hottentota, and the sugar ant, Camponotus storeatus, follow the borders of the Nama and Succulent Karoo biomes respectively (Robertson 2000). In the light of this background the overall objective of this study is to revise the taxonomy and determine the historical drivers of diversification in an important group of arid-adapted ants, the Tetramorium solidum-group, which is mainly restricted to dry semi-desert areas in southern Africa. Members of the Tetramorium solidum-group are commonly encountered seed harvesters yet despite their apparent ecological importance, their taxonomy and biogeography remains largely unresolved. Thirty years elapsed since the last revision of the group by Bolton (1980) and since, ant surveys have considerably expanded the material available for study and provide an opportunity for a fresh perspective on this group. The specific aims of this project were twofold: 1) to revise the species of the Tetramorium solidum-group; and 2) to explore the phylogenetic relationships among members of the group and the bioclimatic factors restricting their current distributional ranges in southern Africa. My study is timely, as to date no attempt has been made to unravel the history of arid-adapted ant diversification in southern Africa. Such information is much needed for identifying areas of high species diversity and endemism (Azuma et al. 2006) and prioritizing areas for conservation (Faith 1992). The thesis consists of three chapters. In chapter one I use morphological characters to review the current taxonomy of the Tetramorium solidum-group. From these data I have compiled an updated identification key for the group and described five new species. In chapter two I have constructed a fossil-calibrated dated phylogeny for Tetramorium solidum-group species in order to explore the historical processes that may have contributed in structuring the current distribution patterns and endemism within and among the species of the group. In this chapter I also explore bioclimatic factors that may restrict the current distribution of members on the Tetramorium solidum-group, using correlative bioclimatic modeling approaches. Chapter three provides a brief and overall conclusion to the study.<br>Financial support from NRF

As flower visitors, ants rarely benefit a plant, commonly disrupting pollination by deterring other flower visitors, or stealing nectar. This thesis examines three aspects of ant-flower interactions, focusing on the occurrence of floral traits that prevent disruption of pollination and a novel means by which ants may influence pollinator behaviour. To assess which types of plant species possess ant-repelling floral traits I carried out a survey of 49 Neotropical plant species. Around a third of these species were repellent to the common generalist ant Camponotus novograndensis (Formicinae). This repellence was positively correlated with large nectar volumes within individual flowers. It appears that there has been selection for floral ant-repellence as a defence against ant thieves in plant species that invest in large volumes of nectar. In some cases these repellent traits were effective against a wide range of ant species. However, in no plant species were predacious ants particularly repelled, indicating that there may be little selective pressure on non-ant-plants to defend potential pollinators from aggressive ants. To investigate the importance of coevolution in determining the effectiveness of ant-repellents, a small but diverse range of Mediterranean plant species were tested with the invasive nectar thieving ant Linepithema humile (Dolichoderinae) and the native but non-nectar thieving ant Messor bouvieri (Myrmecinae). Responses of both ant species to floral traits were very similar. The ability of some plants to restrict access to ant species with which they have no evolutionary history may help to reduce the impact invasive species, as nectar thieves, have on plant-pollinator interactions. It is reported that flowers recently visited by bees and hoverflies may be rejected for a period of time by subsequent bee visitors through the detection of scent-marks. Nectar-thieving ants could potentially influence the foraging decisions of bees in a similar way if they come to associate ant trail pheromones or footprint hydrocarbons with poor reward levels. However, my empirical work found no differences were found in bee visitation behaviour between flowers of Digitalis pupurea (Plantaginaceae), Bupleurum fruticosum (Apiaceae) or Brassica juncea (Brassicaceae) that had been in contact with ants and control flowers. Ant-attendance at flowers of these species may not reduce reward levels sufficiently to make it worthwhile for bees to incorporate ant scent-marks into foraging decisions. Investigations like these into the interactions between ants, flowers and other flower visitors are essential if we hope to understand the part ants play in pollination ecology, and determine how ants have helped shape floral evolution.

This thesis covers the design of an interactive 3D video game with certain unique features and demonstrates the design through a prototype implementation. Insect characters are modeled after human characters and set in a game story. The ants in the game behave similar to leaf-cutter ants. A 3D game environment based on a real ant colony nest is created and used for prototyping the game. Insect behavior based on behavior of real ants is implemented in an interactive 3D environment. The cinematic scenes and the trailer of the game are created to present the game story.

Made available in DSpace on 2014-06-11T19:27:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-05-19Bitstream added on 2014-06-13T20:16:39Z : No. of bitstreams: 1 zavan_c_me_rcla.pdf: 456736 bytes, checksum: 63349cb27cb76d4278ac6d282d04b174 (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>As formigas cortadeiras Atta sexdens, conhecidas popularmente como saúvas, são consideradas pragas agrícolas, e são controladas principalmente por inseticidas tóxicos, altamente inespecíficos, prejudiciais ao homem e outros animais, além de poluir o solo e a água. Estas formigas extraem seus nutrientes através da degradação da matéria vegetal, realizada por polissacaridases (especialmente pectinases), que estão presentes em seU fluido fecal e são produzidas pelo fungo simbionte Leucoagaricus gongylophorus. Assim, a inibição de pectinase seria uma estratégia promissora para controlar as formigas cortadeiras na agricultura de modo mais específico. No presente trabalho, nós buscamos inibidores de pectinase do fluido fecal em várias partes de 22 espécies vegetais, ensaiando 126 extratos brutos, 99 frações ou subfrações e 41 substâncias puras isoladas destes vegetais. Nossos resultados indicam que (1) Cedrela fissilis (Meliaceae) contém inibidores da pectinase presente no intestino das formigas. (2) O flavonóide (-)-catequina foi identificado como composto majoritário ou puro de todas as frações ativas dos extratos de Cedrela fissilis. (3) O flavonóide (-)-catequina, purificado de Cedrela fissilis, assim como extratos desta planta contendo majoritariamente (-)-catequina, inibiram a atividade de pectinase contida no fluido fecal, mas não a atividade de pectinase contida nos jardins de fungo, que provavelmente contém inibidores da ação da (-)-catequina. Assim, sugerimos que o jardim de fungo funciona como uma barreira protetora para as formigas.<br>The leaf-cutting ants Atta sexdens are agricultural pests controled by chemicals which are toxic, not specific and harmful to man, other animal and water resources. They feed on the degradation products of plant material which they cut, harvested to their nest and offer to a symbiotic fungus Leucoagaricus gongylophorus, which grows on this plant material to form the so-called fungus garden. The fungus produces polysaccharidases (especially pectinase) which the ants concentrate in their intestine and secretes in the faecal fluid. Thus, pectinase inhibition would negatively affect the ants nutrition and could be a promising strategy for the control of leafcutters. In the present work, we have searched for pectinase inhibitors in 126 extracts, 99 fractions or sub-fractions and 41 compounds which have been isolated from 22 plant species. Our results showed that (1) Cedrela fissilis (Meliaceae) contains inhibitors of the pectinase which is contained in the ants' faecal fluid. (2) (-)-Catequin, a flavonoid, was the major or the unique compound in every C. fissilis preparation inhibiting the pectinase activity of faecal fluid. (3) These preparations, however, have not inhibited the pectinase activity of the fungus garden. We suggest that the fungus garden acts as a barrier which protects the fungal enzymes against harmful compounds which may be introduced in the ants'nest. the pectinase activity of the fungus garden. We suggest that the fungus garden acts as a barrier which protects the fungal enzymes against harmful compounds which may be introduced in the ants'nest.

Made available in DSpace on 2014-06-11T19:30:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-12-01Bitstream added on 2014-06-13T20:40:01Z : No. of bitstreams: 1 zarzuela_mfm_me_rcla.pdf: 1097166 bytes, checksum: 10e2257e4fb695d3bff1cded5950da82 (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Monomorium floricola é uma das principais espécies de formigas exóticas presentes nas cidades brasileiras e ocorre, em ambientes residenciais, em fábricas de alimentos e em hospitais. As espécies de formigas que ocorrem em ambientes urbanos podem agir como vetor mecânico de disseminação de microrganismos patogênicos e por esse motivo há um grande interesse no estudo de novas formulações de inseticidas visando o controle dessas espécies. Diante disso, o objetivo do presente trabalho foi avaliar a eficácia de produtos na formulação microencapsulada para o controle de Monomorium floricola mantidas em laboratório. Os produtos testados neste trabalho foram o Demand 2,5 CS (Syngenta) e o Dursban 20 ME (Dow Agrosciences) e para tanto, foram realizadas três etapas de testes sendo que em cada uma foi verificada a mortalidade das formigas e o efeito de repelência causado por esses inseticidas. Estas etapas foram divididas em aplicação imediata dos produtos, aplicação residual três meses e aplicação residual seis meses. Paralelamente, foi averiguado o comportamento das formigas que entraram em contato com os produtos. Foram utilizadas 30 colônias para cada etapa de testes, sendo 10 para cada produto e 10 para o controle. Essas colônias foram depositadas em bandejas plásticas, e nelas, foram colocados dois azulejos, sendo que a colônia de Monomorium floricola foi disposta entre eles. O alimento e a água foram colocados sobre cada um dos azulejos. Nas 20 bandejas destinadas aos testes, um dos azulejos foi tratado com o inseticida e o outro não recebeu qualquer tratamento. Nas bandejas controle, um azulejo foi deixado sem qualquer tratamento e o outro foi pincelado com água. As avaliações para o efeito de repelência foram realizadas diariamente por um período de 16 dias...<br>Monomorium floricola is one of the main exotic ant species in Brazilian cities and it occurs in households, food services and hospitals. The ant species that occur in urban environments can be a potential mechanical vector of pathogenic microorganisms and thus there is a great interest in studying new types of insecticide formulations for the ant control. The aim of this work was to evaluate the microencapsulated formulation effectiveness for the Monomorium floricola control in laboratory conditions. The products tested in this work were Demand 2,5 CS (Syngenta) and Dursban 20 ME (Dow Agrosciences) and therefore, three stages of tests were carried out. In each test the mortality of the ants and the repellent effect caused by those insecticides were verified. These stages were divided into immediate application of the products, three-month as well as six-month residual application. At the same time, the ants behavior was evaluated when they got in contact with the products. Thirty colonies were used for each test, being 10 for each product and 10 for the control. The colonies were put in plastic trays, and inside of them, two tiles were placed, and the Monomorium floricola colony was put among them. The food and the water were placed on each one of the tiles. In the 20 trays used for the tests, one of the tiles was treated with the insecticide and the other did not receive any treatment. In the control trays, one tile did not receive any treatment and the other was treated with water. The evaluations for the repellent effect were made daily for 16 days, and the number of the ants present on each tile was counted during the observation. For the mortality analysis the number of dead ants was counted for 13 weeks. The ants behavior observations were made for three hours. The ants that died when getting in contact with... (Complete abstract, click electronic address below)

Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-15Bitstream added on 2014-06-13T19:25:13Z : No. of bitstreams: 1 lacau_lsr_dr_rcla.pdf: 10807132 bytes, checksum: d8357d03fc11bdba98ead511f232cdcb (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>A bioecologia e o comportamento de Cyphomyrmex lectus e de Cyphomyrmex transversus (Formicidae: Myrmicinae: Attini) foram comparados. As colônias de C. lectus são pequenas (73,75 l 46,61 indivíduos) e nidificam no solo, enquanto as de C. transversus são maiores (249,1 l 240,4 indivíduos) e nidificam principalmente sob cocos caídos. O fungo miceliforme de C. lectus e o fungo leveduriforme de C. transversus são cultivados com os mesmos tipos de substratos animais e vegetais. Diariamente, dois picos de forrageamento ocorrem para C. lectus e apenas um para C. transversus. Preparação e incorporação do substrato no fungo são diferentes entre as duas espécies e alguns comportamentos revelaram-se próprios a cada uma. Descobriram-se microcavidades na cutícula da pró-pleura das duas espécies servindo para alojar bactérias simbiontes. A morfologia larval é muito similar entre as duas espécies; no entanto, a morfometria revelou cinco instares larvais para C. transversus e somente quatro para C. lectus. A morfologia do aparelho reprodutor das fêmeas é muito similar entre as duas espécies. Os ovários com três ovaríolos cada um são do tipo politrófico, bem desenvolvidos e funcionais para a rainha, mas reduzidos para a gine e a operária. O desenvolvimento da espermateca é igual entre rainha e gine das duas espécies cujas colônias são monogínicas. A etologia comparada da rainha e da gine revelou que a primeira tem uma função social orientada para a reprodução, enquanto a gine tem um papel similar ao das operárias. O cuidado com os imaturos pelas operárias é semelhante nas duas espécies. Enfim, um excepcional caso de parasitismo múltiplo por vespas Acanthopria (Hymenoptera: Diapriidae)...<br>The ecology and behavior of Cyphomyrmex lectus and Cyphomyrmex transversus (Formicidae: Myrmicinae: Attini) were compared. The colonies of C. lectus are small (73,75 l 46,61 individuals) and nest in the ground, while those of C. transversus are larger (249,1 l 240,4 individuals) and nest mostly under dry coconuts on the floor. The myceliform fungus of C. lectus and the yest-like form fungus of C. transversus are cultivated with the same types of animal and vegetal substrates. Each day, there are two peaks of foraging for C. lectus and only one for C. transversus. Preparation and incorporation of the substrate in the fungus are different between the both species and some behaviors were shown to be characteristic to only one or the other species. Micro-holes that host symbiotic bacteria were found in the cuticle of the propleura of the two species. The larval morphology is very similar between them. The morphometric analysis showed yet five larval instars for C. transversus and only four for C. lectus. The morphology of the reproductive system of the females is very similar between them. The ovaries of three ovarioles belong to the polytrophic type, are well developed and functional in the queen, but reduced in the gyne and the worker. The spermatheca development is the same in the gyne and the queen when colonies are monogyne. The compared behavior of the queen and the gyne showed that the first has a social function oriented to the reproduction, while the gyne has a function similar to a worker. The workers take care of immatures similarly in the both species... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-03-27Bitstream added on 2014-06-13T20:46:50Z : No. of bitstreams: 1 cintra_p_dr_rcla.pdf: 2639332 bytes, checksum: 119f7cee8f096cd058ae02c2f68f50ec (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>As formigas podem adquirir bactérias presentes no ambiente e permitir que elas se desenvolvam nos seus tratos digestórios, transmitindo-as para as formas mais jovens. Estudos filogenéticos, com formigas do gênero Camponotus, apontam uma co-evolução das espécies de bactérias e de formigas, indicando também uma transmissão maternal. As formigas andarilhas, ou tramp species , podem ocorrer em diversos ambientes, entre eles os hospitais, podendo atuar como carreadores de bactérias patogênicas. Não existem na literatura trabalhos que relatem bactérias patogênicas no trato digestório de formigas que ocorrem em ambientes urbanos. O objetivo do presente trabalho foi o de verificar a existência de bactérias patogênicas no trato digestório de formigas que ocorrem em ambientes hospitalares, determinar se essas espécies poderiam funcionar como reservatórios de bactérias e comparar com as bactérias isoladas de formigas de laboratório. Os resultados obtidos indicaram que as formigas não apresentam bactérias patogênicas em seus tratos digestórios, mesmo sendo coletadas em ambiente hospitalar, porém estas podem eventualmente ser isoladas, não fazendo parte da microbiota natural dessas espécies. Bactérias patogênicas foram isoladas nos ninhos mantidos em laboratórios e também nas larvas das espécies Monomorium pharaonis e Monomorium floricola. Devido às diferenças morfológicas entre o trato digestório das operárias adultas e larvas, pode ser explicada a distinção encontrada entre a microbiota isolada. Foram realizados o levantamento da distribuição das espécies de formigas no Hospital das Clínicas da Faculdade de Medicina da UNESP de Botucatu, SP, e no Centro de Saúde de São Carlos, bem como o isolamento das bactérias presentes no trato digestório dos exemplares coletados. Como não foram isoladas bactérias patogênicas...

Thesis (MScAgric (Conservation Ecology and Entomology))--Stellenbosch University, 2008.<br>ENGLISH ABSTRACT: Ant infestations comprising the Argentine ant Linepithema humile (Mayr), common pugnacious ant Anoplolepis custodiens (F. Smith) and cocktail ant Crematogaster peringueyi Emery are a widespread pest problem in South African vineyards. Integrated Pest Management (IPM) programmes aimed at suppressing the problematic honeydew excreting vine mealybug Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) on grapes must include ant control to optimize the effectiveness and efficacy of mealybug natural enemies. If ants are eliminated, natural enemies are able to contain mealybugs below the Economic Threshold Level (ETL). Current strategies for ant control are limited and generally include the application of long term residual insecticides that are detrimental to the environment, labour intensive to apply and can disrupt natural biological control if applied incorrectly. A more practical method of ant control using low toxicity baits was therefore investigated. Field bait preference and bait acceptance assessments aimed at determining bait repellency and palatability, respectively, were carried out during spring, summer and autumn in three vineyards of the Cape winelands region during 2007/08. Five toxicants comprising gourmet ant bait (0.5%), boric acid (0.5%), fipronil (0.0001%), fenoxycarb (0.5%) and spinosad (0.01%) dissolved in 25% sugar solution were tested against a 25% sucrose solution control. Gourmet ant bait was significantly more preferred and accepted by all ant species than the other baits. Laboratory bait efficacy assessments using four insecticides (gourmet, boric acid & spinosad) at concentrations of 0.25; 0.5; 1; 2 and 4 times the field dose and fipronil at 0.015625; 0.03125; 0.0625; 0.125; 0.25 times the field dose were carried out. Results revealed that boric acid (2%), gourmet ant bait (2%) and fipronil (1.0 X 10-5%) exhibited delayed toxicity for L. humile and C. peringueyi while spinosad (0.01%) showed delayed action on L. humile. Field foraging activity and food preference tests were also carried out for the three ant species during 2007/08. Foraging activity trials revealed that vineyard foraging activity of L. humile is higher relative to A. custodiens and C. peringueyi. This means fewer bait stations are required for effective L. humile control making low toxicity baits a more affordable and practical method of controlling L. humile than the other two ant species. Food preference trials showed that L. humile and C. peringueyi have a high preference for sugar while A. custodiens significantly preferred tuna over other baits. However, all ant species had a preference for wet baits (25% sugar water, 25% honey, tuna & agar) as opposed to dry ones (fish meal, sorghum grit, peanut butter & dog food). This research concludes that low toxicity baits show potential in ant pest management and can offer producers with a more practical, economical and environmentally friendly method of ant control which is compatible with vineyard IPM programmes.<br>AFRIKAANSE OPSOMMING: Mierbesmetting wat uit die Argentynse mier Linepithema humile (Mayr), die gewone malmier Anoplolepis custodiens (F. Smith) en die wipstertmier Crematogaster peringueyi Emery bestaan, is ’n plaagprobleem wat wydverspreid in Suid-Afrikaanse wingerde voorkom. Programme vir geïntegreerde plaagbeheer (GPB) wat daarop gemik is om die wingerdwitluis Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) – wat ’n probleem is weens die heuningdou wat dit afskei – op druiwe te beheer, moet mierbeheer insluit om sodoende die uitwerking en doeltreffendheid van die witluis se natuurlike vyande die beste te benut. As miere uitgeskakel kan word, sal dit vir die natuurlike vyande moontlik wees om die witluis sodanig te beheer dat dit onder die ekonomiese drempelvlakke (EDV) bly. Huidige strategieë om miere te beheer, is beperk en sluit gewoonlik die toediening van insekdoders in wat lank neem om in die grond af te breek, wat skadelik vir die omgewing is, waarvan die toediening arbeidsintensief is en wat die natuurlike biologiese beheer kan versteur indien dit verkeerd toegepas word. Daarom is ’n meer praktiese metode ondersoek waar miere deur die gebruik van lae toksisiteit lokase beheer word. Ondersoeke na lokaasvoorkeure en lokaasaanvaarbaarheid in die praktyk, wat daarop gemik is om te bepaal of die lokaas onderskeidelik afstootlik en smaaklik bevind word, is oor lente, somer en herfs in drie verskillende wingerde in die Kaapse wynlandstreek gedurende die 2007/08-seisoen uitgevoer. Vyf gifstowwe, bestaande uit gourmet ant bait (0.5%), boorsuur (0.5%), fiproniel (0.0001%), fenoksiekarb (0.5%) en spinosad (0.01%) wat in ’n 25%-suikeroplossing opgelos is, is getoets teenoor ’n kontrole wat uit ’n 25%-sukrose-oplossing bestaan. Al die mierspesies het gourmet ant bait bo die ander lokase verkies en aanvaar. In die laboratorium is ondersoeke gedoen om die doeltreffendheid van die lokase te bepaal deur vier insekdoders (gourmet ant bait, boorsuur en spinosad) te gebruik in konsentrasies van 0.25; 0.5; 1; 2 en 4 keer die dosis in die praktyk en fiproniel teen 0.015625; 0.03125; 0.0625; 0.125; 0.25 keer die dosis in die praktyk. Resultate het getoon dat boorsuur (2%), gourmet ant bait (2%) en fiproniel (1.0 X 10-5%) vertraagde toksisiteit getoon het vir L. humile en C. peringueyi, terwyl spinosad (0.01%) ’n vertraagde uitwerking getoon het op L. humile. Toetse om kossoekaktiwiteite in die praktyk en die voedselvoorkeure van die drie mierspesies te ondersoek, is ook gedurende die 2007/08-seisoen gedoen. Proewe oor kossoekaktiwiteite het getoon dat hierdie aktiwiteite in die wingerd by L. humile hoër is in verhouding met A. custodiens en C. peringueyi. Dit beteken dat minder lokaasstasies nodig is om L. humile doeltreffend te beheer en lei daartoe dat lae toksisteit lokaas ’n beter manier is om L. humile te beheer as die ander twee mierspesies. Proewe oor voedselvoorkeure het aangedui dat L. humile en C. peringueyi ’n groot voorkeur toon vir suiker, terwyl A. custodiens ’n duidelike voorkeur vir tuna het. Alle mierspesies het egter ’n voorkeur vir nat lokaas (25% suikerwater, 25% heuning, tuna en agar), eerder as droë lokaas (vismeel, sorghumgruis, grondboontjiebotter en hondekos) getoon. Uit hierdie navorsing word afgelei dat lae toksisteit lokaas potensiaal toon in mierbeheer en dat dit produsente ’n meer praktiese, ekonomiese en omgewingsvriendelike metode van mierbeheer kan bied wat met GPB-programme in die wingerd versoenbaar is.

Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-04-18Bitstream added on 2014-06-13T20:07:20Z : No. of bitstreams: 1 oliveira_mfss_dr_rcla.pdf: 927200 bytes, checksum: 190eb33eedd48dc2ac945922c0eb1a87 (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>O presente trabalho teve por objetivo avaliar a eficiência dos óleos brutos de Carapa guianensis Aubl. (andiroba), Elaeis guineensis Jacq. (dendê), Sesamum indicum L. (gergelim), Ricinus communis L. (mamona), Azadirachta indica Juss (nim), Theobroma cacao L. (cacau), Anacardium occidentale L. (caju) e dos extratos de Anacardium occidentale no controle de formigas cortadeiras, utilizando como alvo a espécie Atta sexdens rubropilosa. De acordo com os resultados obtidos nos testes de toxicidade, alguns óleos brutos e extratos foram selecionados para serem incorporados em iscas ou aplicados por nebulização e testados em colônias de laboratório. Os óleos brutos e extratos mais eficientes no controle dessas colônias foram selecionados para testes de campo. Os resultados obtidos nos testes permitiram selecionar os óleos brutos de C. guianensis, E. guineensis, S. indicum, R. communis, A. indica, A. occidentale e os extratos hexânico, diclorometano, acetato de etila e metanólico de A. occidentale para serem aplicados por nebulização e os óleos brutos de E. guineensis, A. indica e A. occidentale para serem incorporados em iscas e testados em colônias de laboratório. Em colônias de laboratório, a nebulização com os óleos brutos de C. guianensis, E. guineensis, S. indicum, R. communis e A. indica não causaram efeitos deletérios nas colônias e, portanto, não devem ser indicados como produtos nebulizáveis no controle de formigas cortadeiras. No entanto, o óleo bruto e os extratos hexânico, diclorometano, acetato de etila e metanólico de A. occidentale propiciaram a extinção das colônias. As iscas contendo óleos brutos de E. guineensis, A. indica e A. occidentale não causaram nenhum efeito nas colônias e, portanto, não devem ser indicadas para o controle de formigas cortadeiras. O óleo bruto de A. occidentale foi testado em colônias de campo de Atta sexdens rubropilosa e Atta bisphaerica por meio da termonebulização e da nebuli<br>The present work aimed to evaluate the efficiency of crude oils of Carapa guianensis Aubl. (crabwood), Elaeis guineensis Jacq. (African oil palm), Sesamum indicum L. (sesame), Ricinus communis L. (castor beans), Azadirachta indica Juss (neem), Theobroma cacao L. (cocoa), Anacardium occidentale L. (cashew nut) and crude extracts of Anacardium occidentale on leafcutting ants control, using Atta sexdens rubropilosa as model. Toxicity bioassays with ant workers were done using: 1) treatments by incorporation of crude oils or extracts in artificial diet and 2) treatments by topic application of crude oils or extracts on the ants pronotum. According to obtained results in toxicity tests, some crude oils and extracts were select to be incorporated in baits or applied by nebulization and tested on laboratory colonies. The crude oils or extracts more efficient on laboratory colonies control were tested on field grown up colonies. The obtained results in all toxicity tests permitted to select crude oils of C. guianensis, E. guineensis, S. indicum, R. communis, A. indica, A. occidentale and hexane, dichloromethane, ethyl acetate and methanol extracts of A. occidentale to be applied by nebulization and crude oils of E. guineensis, A. indica and A. occidentale to be incorporated in baits and tested on laboratory colonies. On laboratory colonies, the nebulization with crude oils of C. guianensis, E. guineensis, S. indicum, R. communis and A. indica didn't cause any effect on colonies. Therefore, these crude oils don't must be used to leaf-cutting ants control. However, crude oil and hexane, dichloromethane, ethyl acetate and methanol extracts of A. occidentale propitiated the extinction of colonies. The E. guineensis, A. indica and A. occidentale baits didn't any cause effect on colonies hence it follows that these baits don't must be used to leaf-cutting ant's control.

Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-10-14Bitstream added on 2014-06-13T20:46:50Z : No. of bitstreams: 1 diniz_ea_dr_rcla.pdf: 624691 bytes, checksum: 0bce2c8708444f08d4428ee602667889 (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>O presente trabalho teve como objetivo o estudo da evolução dos comportamentos de preparação do substrato, cuidado com a cria e cuidado com a rainha e alados em formigas cultivadoras de fungo. Estas formigas pertencem à tribo Attini, subfamília Myrmicinae, e ocorrem exclusivamente no continente americano. Esta tribo contém aproximadamente 230 espécies, porém pouco se conhece da biologia da maioria delas, graças ao fato de serem extremamente crípticas e de não apresentarem importância econômica, como as formigas cortadeiras, que são as mais estudadas. Foram utilizadas seis espécies, que representam bem os diversos níveis da filogenia da tribo: Acromyrmex disciger, Apterostigma pilosum, Mycetarotes parallelus, Myrmicocrypta sp., Trachymyrmex fuscus e Trachymyrmex sp. nov. Os comportamentos foram estudados em ninhos mantidos em laboratório, com o auxílio de micro-câmeras e um aparelho gravador de vídeo. Os comportamentos foram analisados, caracterizados e quantificados. Os resultados foram divididos em três capítulos de acordo com o tipo de comportamento. No capítulo sobre a evolução dos comportamentos de preparação do substrato foi observado que, basicamente, o processo evoluiu no sentido de aumentar a capacidade das operárias em decompor inicialmente o substrato. As espécies basais, A. pilosum, M. parallelus e Myrmicocrypta sp. apresentaram um processamento mais simples com um número menor de comportamentos e principalmente sem os comportamentos do tratamento químico, que é responsável pela fragmentação do substrato ao mesmo tempo em que ele é tratado com enzimas digestivas. As duas espécies do gênero Trachymyrmex apresentaram um processo mais complexo com grande participação do tratamento químico. Em A. disciger, que é uma cortadeira, há uma intensa especialização do sistema de castas para o aumento da eficiência...<br>This work aims to study the evolution of the behaviors of substrate preparation, brood, queen and winged forms care in fungus growing ants. These ants are included in the tribe Attini, subfamily Myrmicinae, and occur exclusively in the american continent. This tribe contains approximately 230 species, but little is known about the biology of most of them, tanks to the fact that they show very cryptic habits and are not economically important, like the leaf cutting ants, which are the most studied. Six species were used in this work, which represent well all the levels of the phylogeny of the tribe: Acromyrmex disciger, Apterostigma pilosum, Mycetarotes parallelus, Myrmicocrypta sp., Trachymyrmex fuscus and Trachymyrmex sp. Nov. The behaviors were studied in laboratory nests, with a set of micro cameras and a video recording device. The behaviors were analyzed, characterized and quantified. The results were summarized and discussed in tree chapters, arranged by type of behavior. In the chapter about the evolution of the substrate preparation behaviors, basically it is assumed that this process evolved in order to develop the capacity of previously decompose the substrate by the workers. In the basal species, A. pilosum, M. parallelus and Myrmicocrypta sp. this process is very simple with a small number of behaviors and principally without the behaviors of chemical treatment, which are responsible for the fragmentation of the substrate as it is treated by with digestive enzymes. In the two species of the genus Trachymyrmex, the process became more complex and showed a greater participation of these behaviors. A. disciger, witch is a leaf cutting ant, showed an extensive specialization of physical castes in all the phases of the process which elevated it’s efficiency. In the chapter about the evolution of the behaviors of brood care... (Complete abstract click electronic access below)

Thesis (M.S.)--University of Toledo, 2010.<br>Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for the degree of Master of Science in Biology (Ecology track)." "A thesis entitled"--at head of title. Title from title page of PDF document. Bibliography: p. 38-42 and 51.

Field trials were conducted in 1988 to evaluate the effectiveness of Steinernema (=Neoaplectana) carpocapsae (Weiser) in controlling the fire ant. Infective juveniles (IJ) of the nematode were applied as drench on 235 and 422 mounds, respectively for 2-month summer and 6-week fall evaluation periods. In comparative trials, amidinohydrazone (Amdro) was applied to 249 (summer) and 65 (fall) active mounds, with 245 (summer) and 78 (fall) untreated active as controls. Nematode treatments resulted in an average of 47% control (Abbott's formula) in summer trials and 19-88% control in the fall trials, compared with 39% and 47% control, respectively with amidinohydrazone. Active mounds treated with nematodes or amidinohydrazone had significantly fewer individuals than control mounds in summer trials.

Phenotypic plasticity is the ability for a single genotype to give rise to alternative adaptive phenotypes in response to environmental conditions facilitating their survival. In some cases, environmental conditions can influence the course of development of an organism, leading to the induction of novel phenotypic variation, the raw materials for selection in evolution. Although this fact has the potential to unify the disparate fields of ecology, development and evolution, we have only begun to investigate the underlying molecular mechanisms that translate the environment into phenotypic diversity. Ants are highly plastic; during development a single genotype can give rise to an array of alternative phenotypes related to dramatic differences in morphology, longevity, reproduction and behavior. This environmental sensitivity is the basis for the diversity of complex ant caste systems. Here, I used ant development of the hyperdiverse genera Pheidole and Camponotus as models to investigate my major goal, which is to understand how ecology (environment) acts on development, generating morphological variation, which can then lead to morphological diversification and evolution. The first specific goal (Chapter 2) of my thesis is to investigate the hormonal and developmental genetic basis underlying the evolution of novel worker ant subcastes. Specifically, the genus Pheidole is composed of over 1000 species, all of which comprise a complex worker caste system of minor workers and soldiers. In a hand full of these species, there exists an additional novel worker subcaste, the supersoldier. Through phylogenetic and developmental genetic analysis, I determined that this subcaste has evolved in parallel in different species. I then discovered through field observations and hormonal manipulations that there exists an ancestral developmental potential in this group: all Pheidole species have the hidden capacity to produce supersoldiers through environmental induction, the recurrence of which can lead to their evolution. The second specific goal of my thesis (Chapter 4) is to investigate the epigenetic mechanisms that translate environmental conditions into morphological variation within castes. Specifically, I investigated the involvement of DNA methylation in generating continuous sizing in the worker caste of the genus Camponotus. I discovered that DNA methylation is responsible for generating a continuous distribution of worker size and that one of its primary targets is the gene Egfr. Furthermore, the methylation level of Egfr is associated with quantitative variation in worker size and pharmacological inhibition of EGFR signaling demonstrated that this pathway is capable of generating the continuous distribution of size found within this caste. DNA methylation is an epigenetic mechanism that is known to cause transgenerational inheritance and therefore it can facilitate the evolution of environmentally generated quantitative variation. Collectively, the results of my thesis show how the environment acts on development through the integration of hormones, genes and epigenetic mechanisms to generate phenotypic variation for selection to act on. Perhaps we are coming closer to a point in time in evolutionary theory when we can say that the environment is as important in generating phenotypic variation as it is in the process of selection.<br>La plasticité phénotypique est l'habileté d'un génotype unique de produire des phénotypes adaptatifs alternes en réponse à des conditions environnementales facilitant leur survie. Dans certains cas, les conditions environnementales peuvent influencer le cours du développement d'un organisme, menant à l'induction d'une variation phénotypique nouvelle, qui est la matière brute pour la sélection en évolution. Bien que ce fait ait le potentiel d'unifier les champs distincts de l'écologie, du développement et de l'évolution, on commence seulement à étudier les mécanismes moléculaires fondamentaux qui traduisent l'environnement en diversité phénotypique. Les fourmis démontrent une grande plasticité phénotypique; durant le développement, un génotype unique peut produire une diversité de phénotypes adaptatifs qui démontrent des différences dramatiques de morphologie, de longévité, de reproduction et de comportement. Cette sensibilité environnementale est à la base de la diversité des systèmes complexes de castes chez les fourmis. Ici, j'ai utilisé le développement des genres hyperdiversifiés Pheidole et Camponotus comme modèles pour investiguer mon but principal, qui est de comprendre comment l'écologie (l'environnement) agit sur le développement, en générant de la variation morphologique qui peut par la suite mener à une évolution morphologique. Le premier objectif spécifique de ma thèse (Chapitre 2) est d'investiguer les bases hormonales et du développement des nouvelles sous-castes ouvrières chez les fourmis. Plus spécifiquement, le genre Pheidole est composé de plus de 1000 espèces, toutes démontrant un système de castes ouvrières complexe comprenant des ouvrières mineurs et des soldates. Chez un petit groupe de ces espèces, il existe une caste ouvrière additionnelle, la supersoldate. En utilisant des analyses phylogénétiques et de génétique du développement, j'ai déterminé que cette sous-caste a évolué en parallèle chez les différentes espèces. J'ai par la suite découvert, par des observations sur le terrain et des manipulations hormonales, qu'il existe un potentiel ancestral de développement dans ce groupe: toutes les espèces de Pheidole ont une capacité cachée de produire des supersoldates par induction environnementale, cette récurrence pouvant mener à leur évolution. Le second objectif spécifique de ma thèse (Chapitre 4) est d'investiguer les mécanismes épigénétiques qui traduisent les conditions environnementales en variation morphologique entre les castes. Plus spécifiquement, j'ai investigué le rôle de la méthylation de l'ADN dans l'élaboration d'une distribution de taille continue chez la caste ouvrière de Camponotus. J'ai découvert que la méthylation de l'ADN génère une distribution continue de taille chez la caste ouvrière et que l'une de ses cibles principales est le gène Egfr. D'ailleurs, le niveau de méthylation de Egfr est associé à une variation quantitative de la taille des ouvrières et une inhibition pharmacologique de la signalisation EGFR a démontré que cette voie de signalisation est capable de générer la distribution continue des tailles dans cette caste. La méthylation de l'ADN est un mécanisme épigénétique qui est connu pour causer une héritabilité transgénérationelle et donc, elle peut faciliter l'évolution d'une variation quantitative générée par l'environnement. Collectivement, les résultats de ma thèse montrent comment l'environnement agit sur le développement par l'intégration des hormones, des gènes et des mécanismes épigénétiques pour générer de la variation phénotypique sur laquelle la sélection naturelle peut agir par la suite. Peut-être que nous nous rapprochons d'un moment où la théorie de l'évolution peut proposer que l'environnement soit également important pour générer de la variation phénotypique qu'il peut l'être au cours du processus de sélection.

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (page 105).<br>In 2012, Feinerman et al. introduced the Ants Nearby Treasure Search (ANTS) problem [1]. In this problem, k non-communicating agents with unlimited memory, initially located at the origin, try to locate a treasure distance D from the origin. They show that if the agents know k, then the treasure can be located in the optimal O(D+ D²/k) steps. Furthermore, they show that without knowledge of k, the agents need [omega]((D + D²/k) - log¹+[epsilon] k) steps for some [epsilon] > 0 to locate the treasure. In 2014, Emek et al. studied a variant of the problem in which the agents use only constant memory but are allowed a small amount of communication [2]. Specifically, they allow an agent to read the state of any agent sharing its cell. In this paper, we study a variant of the problem similar to that in [2], but where the agents have even more limited communication. Specifically, the only communication is loneliness detection, in which an agent in able to sense whether it is the only agent located in its current cell. To solve this problem we present an algorithm HYBRID-SEARCH, which locates the treasure in O(D - log k + D² /k) steps in expectation. While this is slightly slower than the straightforward lower bound of [omega](D + D² /k), it is faster than the lower bound for agents locating the treasure without communication.<br>by Casey O'Brien.<br>M. Eng.