The main objective of this study was to examine the abundance and diversity of ants in suburban sites following vegetation removal or modification for development. This research examines the capacity of suburban sites to support ant diversity, which is dependent on the site characteristics and their surrounding environment. The study focused on 29 suburban garden and 3 suburban reserve sites on the Gold Coast, Queensland, Australia. This region, through continuing land development, undergoes ongoing habitat disturbance and modification. Ground-dwelling ants were collected by pitfall trapping in study sites over three summers between 1997 and 1999. In total, 28,512 ants from 60 species in 31 genera were collected. Garden sites that maintain vegetation structural diversity were found to be most similar to reserve sites in terms of ant community composition. These sites were highest in ant richness and diversity and contained particularly high proportions of specialized ant species. Sites in close proximity to remnants of native vegetation contained higher species diversity and a greater proportion of specialized ant species. The introduced tramp ant, Pheidole megacephala was found in 28 of the 32 sites and was found to significantly reduce ant species richness and diversity and displace the dominant ant Iridomyrmex sp. 1 in suburban environments. This ant poses a serious threat to the recovery of a diverse ant fauna to suburban environments. Ant community composition was shown to vary significantly among suburban sites. The ant functional groups commonly found in disturbed sites were abundant in open sites with little canopy cover in this study. Sites that provided vegetation structural diversity and areas of closed canopy supported similar functional groups to natural vegetation remnants. These results indicate that ant communities in suburban environments respond to disturbance in a similar manner to ant communities in tropical forests and rainforests. The dominance by functional groups and presence of specialized species may therefore be used as an indicator of disturbance and the restoration of suitable habitat in suburban sites. The presence of specialized species of ants in suburban garden sites and their clear preference for particular site characteristics indicate that these species utilize resources available in the suburban matrix. These results indicate that residential suburban sites are of value in the enhancement of ant diversity in fragmented landscapes and that they may provide supportive habitat to, and act as corridors between, vegetation fragments. In order to preserve biodiversity within suburban environments, landowners should be advised to retain as much existing vegetation within a site as possible. Clearing should be limited to that necessary to allow construction of dwellings and for safety. In addition, landowners should be encouraged to establish or maintain structurally diverse vegetation layers within sites in order to provide diverse microenvironments for fauna habitat.

Ce travail porte sur la dispersion des graines par les fourmis et se divise en deux parties : l’une expérimentale (Chapitres 1, 2 & 3) et l’autre synthétique (Chapitres 4 & 5). L’approche expérimentale a consisté en une exploration en conditions de laboratoire des comportements des fourmis à deux étapes du processus de myrmécochorie: à la source de graines et dans le nid. Des graines des plantes myrmécochores Viola odorata et Chelidonium majus ont été présentées aux fourmis Lasius niger et Myrmica rubra. Chaque étape de la séquence myrmécochorique a généré une variabilité des comportements propre à chacun des quatre couples fourmis-graines. L’élaiosome n’attire pas les fourmis à distance. Les fourmis suivent toujours la même séquence de comportements : antennation, manipulation et prise des graines. Le nombre d’antennations et de manipulations avant la prise de graines peut être considéré comme un indicateur de l’« hésitation » des fourmis à prendre les graines. L’espèce à tendance carnivore Myrmica rubra a été plus rapide et efficace dans la prise de graines que l’espèce éleveuse de pucerons Lasius niger. Parallèlement, les fourmis ont moins antenné, moins manipulé et plus pris de graines de Chelidonium majus, ce qui montre un intérêt particulier pour cette espèce. Un jour après l’expérience, toutes les graines des deux espèces se trouvaient dans les déchets à l’extérieur du nid, avec au moins la moitié des élaiosomes consommés (Chapitre 1). Lors du passage des graines à l’intérieur du nid, les fourmis Myrmica rubra ont également montré une capacité à traiter les graines rapidement, en montrant une dynamique d’arrachage de l’élaiosome et de rejet des graines hors du nid plus rapide. Le taux d’arrachage de l’élaiosome a été influencé par l’espèce de graine, plus important pour les graines de Chelidonium majus. Nous avons montré qu’une proportion variable de graines rapportées au nid (moins de la moitié) étaient déposées directement au contact des larves, les autres étant traitées ailleurs par les ouvrières ou laissées temporairement à l’abandon dans le nid. Par ailleurs, les dynamiques de rejet des items hors du nid ont curieusement été peu influencées par l’espèce de graine. Pour une graine, le fait de ne plus avoir d’élaiosome diminue le nombre moyen d’ouvrières qui la contacte simultanément. Parallèlement, même si la réponse n’est pas de type « tout ou rien », l’absence d’élaiosome accroit aussi la probabilité qu’une graine a d’être rejetée. (Chapitre 2). Nous avons isolé expérimentalement le paramètre de dessiccation des graines afin mesurer son influence sur le taux de prises. La dessiccation progressive des graines réduit les taux de prises par les fourmis Myrmica rubra. La réhydratation des mêmes graines leur permet de retrouver une attractivité et donc une valeur fonctionnelle prolongée. Les graines de Viola odorata perdent presque toute attractivité après 4 jours de dessiccation et leur réhydratation ne rétabli que faiblement leur attractivité. A l’inverse, les graines de Chelidonium majus gardent un tiers de leur attractivité après un mois de dessiccation et leur réhydratation restaure presque entièrement leur attractivité (Chapitre 3). La synthèse bibliographique a permis de dresser un aperçu des principales caractéristiques des fourmis dispersatrices de graines myrmécochores. Certains traits « généralistes » rendent les rencontres entre fourmis et graines très probables : leur ubiquité et diversité taxonomique, leur régime alimentaire omnivore, et leur fourragement « diffus » et opportuniste. Les fourmis possèdent des traits qui les rendent uniques par rapport aux autres insectes : le fourragement au sol, la capacité à transporter de la nourriture, ainsi que la nidification. Certains traits des fourmis ont une influence considérable sur la dispersion des graines : leur taille, les préférences de régime alimentaire, la phénologie, la capacité d’apprentissage et la fréquence de déménagement des nids. Nous développons également l’hypothèse que la rapidité et l’efficacité du traitement des graines par les fourmis seraient une conséquence d’un comportement hygiénique des fourmis à tendance carnivore, habituées à gérer des proies périssables (Chapitre 4). Nous avons dressé pour la première fois une liste des espèces de plantes myrmécochores et potentiellement myrmécochores des régions d’Europe tempérée (260 spp.). Nous montrons que ces dernières sont majoritairement herbacées, et ont tendance à fleurir plus précocement que les autres espèces. La proportion de graines myrmécochores comprises entre 1 et 3 mm et entre 0,6 et 10 mg est plus importante que dans le reste de la flore (Chapitre 5). / This study concerns seed dispersal by ants and is divided in two parts: one experimental (chapters 1, 2 & 3), and one synthetic (chapters 4 & 5). Experimental work consisted in a series of laboratory experiments, in which ant behaviour was studied at two stages of the dispersal process: at the seed source and inside the nest. Seeds of the myrmecochorous plants Viola odorata and Chelidonium majus were presented to two ant species: Lasius niger and Myrmica rubra. Each stage of the myrmecochory sequence generated a variability of behaviours for each of the four ant-seed pairs. The elaiosomedo not attract seed at a distance. Ants followed always the same behavioural sequence: antennations, manipulations, and removal. The number of antennations and manipulations before removal can be considered as a measure of ants’ “hesitation” to remove seeds. The carnivorous species Myrmica rubra was faster and more efficient at taking seeds than the aphid-tending Lasius niger. At the same time, ants antennated and manipulated less Chelidonium majus seeds, which shows a particular interest for this seed species. One day after the experiment, all seeds of both species were located outside the nest in the refuse piles. At least half of their elaiosomes had been consumed (chapter 1). Inside the nest, Myrmica rubra also showed a great ability to treat seeds quickly, i.e. quicker dynamics of elaiosome removal and seed rejection outside the nest. Elaiosome removal rates were influenced by seed species (higher for Chelidonium majus). We showed that a variable proportion of seeds (less than half) was directly deposited in contact with larvae. The rest of the seeds were handled elsewhere by workers, or left temporarily unattended in the nest. Dynamics of seed rejection outside the nest were curiously little influenced by the seed species. For a seed, to loose the elaiosome decreased the number of workers manipulating it. At the same time, even if the rejection response is not automatic, the absence of elaiosome increases the probability for a seed to be rejected (Chapter 2). We isolated the desiccation parameter in order to measure its influence on seed removal rates. Progressive seed desiccation reduced Myrmica rubra removal rates. Rehydration of the same seeds restored their attractiveness, thereby prolonging their functional life. Viola odorata seeds lost almost all their attractiveness after 4 days of desiccation, and rehydration only restored a reduced part of their attractiveness. On the contrary, Chelidonium majus seeds kept one third of their attractiveness after one month of desiccation, and recovered almost all their attractiveness after rehydration (Chapter 3). The bibliographic review allowed us to compile an outline of the main features of seed-disperser ants. Some generalist features highly increase the probability that ants encounter seeds: their ubiquity and taxonomic diversity, omnivorous diet and their opportunistic “diffuse” foraging. Among insects, ants have unique traits that make them broad dispsersers: ground foraging, the ability to transport items, and nesting behaviour. Some other traits have a great influence on the seed dispersal system: the ant body size, their diet preferences, the phenology of the colony, the learning, and the frequence of nest relocation. We also develop the hypothesis according to which, handling efficiency of ants is a byproduct of hygienic behaviour of carnivorous oriented species, since they are used to manage perishable preys (Chapter 4). We compiled the first list of myrmecochorous and potentially myrmecochorous plants species of European temperate regions (260 spp.). We show that these plants are mainly herbaceous. They also tend to flower earlier than the whole flora. The proportions of myrmecochorous seeds having a size range between 1 and 3 mm, and a weight range between 0.6 and 10 mg are higher than in the rest of the flora (Chapter 5).

La variabilitat de la depredació de llavors en l'espai i temps poden oferir oportunitats a les males herbes per escapar dels depredadors. Els nivells de depredació en cereals de secà van ser dels més alts mai registrats cultius extensius (46-100%). El moment de producció de les llavors de males herbes es superposava amb el període de major demanda. La distribució espacial dels nius era no aleatòria. Els nius grans estaven més regularment distribuïts, els nius petits més agrupats. Les formigues van respondre amb taxes de depredació extremadament elevades (99-100%) a totes les densitats de llavors aplicades L. (1000-20.000 llavors m-2), amb una resposta denso-independent. La mida de rodal va influir en les taxes de depredació per formigues. Va ser major en els rodals més grans (99-100%) i menor en els més petits (78-94%). Aquesta investigació va quantificar la variabilitat espaciotemporal en la depredació de llavors de cereals de secà i l'eficàcia.Summary / La variabilidad de la depredación de semillas en el tiempo y espacio ofrecen oportunidades a las malas hierbas para escapar de los depredadores. Los niveles de depredación en cereales de secano fueron entre los más altos registrados jamás en cultivos extensivos (46-100%). El momento de producción de semillas de las malas hierbas se superponía con el período de mayor demanda. La distribución espacial de los nidos era no aleatoria. Los nidos grandes estaban más regularmente distribuidos, los nidos pequeños más agrupados. Las hormigas respondieron con tasas de depredación extremadamente elevadas (99-100%) a todas las densidades de semillas aplicadas (1.000 a 20.000 semillas m-2), con respuesta denso-independiente. El tamaño de parche influyó en las tasas de depredación por hormigas. Fue mayor en los parches más grandes (99-100%) y menor en los más pequeños (78-94%). Esta investigación cuantificó la variabilidad espacio-temporal de la depredación de semillas en cereales de secano y la eficacia. / The variability of seed predation in time and space may provide opportunities to weeds to escape predation. Seed predation rates by harvester ants in dryland cereals were among the highest ever recorded on arable fields (46-100%). The timing of weed seed shed overlapped with the period of highest demand. The spatial nest arrangement appeared to be non-random. The large nests were more or less regularly distributed, small nests tended to be more clumped. Harvester ants responded with extremely high predation rates (99-100 %) to all densities of Lolium multiflorum L. seeds applied (1000-20000 seeds m-2), and the response was density independent. Patch size influenced predation rates by harvester ants. Estimated seed predation rate was highest in the largest patches (99-100%), and lowest in the smallest patches (78-94 %). The current research quantified temporal and spatial variability in seed predation in dryland cereals and the influence to the efficacy of granivory.

This thesis develops a simulation and visualization of a path finding algorithm based on ant pheromone paths created in 3D space. The simulation is useful as a demonstration of a heuristic approach to NP-complete problems and as an educational tool for demonstrating how ant colonies gather food. An interactive real time 3D visualization is built on top of the simulation. A graphical user interface layer allows user interaction with the simulation and visualization.

Made available in DSpace on 2014-06-11T19:35:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-01-29Bitstream added on 2014-06-13T20:26:47Z : No. of bitstreams: 1 nondillo_a_dr_rcla.pdf: 3172651 bytes, checksum: 53229dbd5914c1786c310cc4b6e56986 (MD5) / A pérola-da-terra Eurhizococcus brasiliensis (Wille, 1922) (Hemiptera: Margarodidae) – cochonilha de raiz- é a principal praga da videira no Brasil, pois ao sugar a seiva da planta pode causar redução na produção e sua morte. A dispersão da cochonilha é realizada por formigas que se associam aos cistos em busca dos excrementos açucarados. Este trabalho objetivou determinar a diversidade da fauna de formigas presente em parreirais com a presença de pérola-da-terra nos Estados do Rio Grande do Sul e Santa Catarina; conhecer a interação de Linepithema micans (Forel, 1908) (Hymenoptera: Formicidae) e E. brasiliensis em raízes de videira; conhecer aspectos da bioecologia de L. micans como a descrição de larvas, o ciclo de vida sazonal e a atividade de forrageamento; avaliar a atratividade de substâncias açucaradas e ricas em proteínas e lipídios e avaliar o efeito de inseticidas e formulações de iscas tóxicas visando o controle de L. micans. No levantamento realizado no Rio Grande do Sul e Santa Catarina, L. micans foi classificada como muito abundante, dominante e muito frequente em todas as localidades amostradas. Em relação a interação entre estes dois organismos, os resultados revelaram que L. micans transporta e auxilia na fixação de E. brasiliensis nas raízes da videira. As larvas apresentam traços típicos do gênero Linepithema (Mayr, 1866), em relação ao formato geral do corpo e da mandíbula, a presença de uma protuberância abdominal dorsal, nove pares de espiráculos e pelos simples. O ciclo de vida sazonal de L. micans em parreirais tem início no final do inverno (julho - agosto) e começo da primavera (setembro) com o aumento da oviposição pelas rainhas. Durante os meses quentes do ano foi possível observar um número maior de ninhos dispersos nos parreirais, constituídos principalmente por ovos e pupas... / The ground-pearl Eurhizococcus brasiliensis (Wille, 1922) (Hemiptera: Margarodidae) is a soil scale considered as the main pest of vineyards in Brazil, because while sucking the plant sap it causes production reduction and death. The dispersion of ground-pearl is made by ants that associate to cysts in search of sugary excretions. The main objectives of this work were: to determine the diversity of ant fauna present in vineyards with the presence of ground-pearl in the states of Rio Grande do Sul and Santa Catarina; to know the interaction between Linepithema micans (Forel, 1908) (Hymenoptera: Formicidae) and E. brasiliensis in vine roots; to know aspects of L. micans’ bioecology, such as description of the larvae, seasonal life cycle, and foraging activity; and to evaluate the attractiveness of sweet and highfat and -protein substances and to evaluate the effect of insecticides and toxic bait formulations aimed to control L. micans. In a survey conducted in Rio Grande do Sul and Santa Catarina L. micans was classified as very abundant, dominant and very common in all cities sampled. As regards the interaction between these organisms, the results revealed that L. micans transports and aids the fixation of E. brasiliens in vine plants. The larvae of L. micans displayed typical traits of the genus Linepithema Mayr as regards general body and mandible shape, the presence of a dorsalabdominal protuberance, nine pairs of spiracles, and simple hairs. The seasonal life cycle of L. micans in vineyards began in late winter (July-August) and early spring (September) with the deposition of eggs by queens. During the warm months of the year it was possible to observe a larger number of nests spread throughout the vineyards, consisting primarily of eggs and pupae. During the winter the colonies were composed by workers, with predominance of... (Complete abstract click electronic access below)

Made available in DSpace on 2015-03-26T13:30:44Z (GMT). No. of bitstreams: 1 texto completo.pdf: 222838 bytes, checksum: f5c4d1de7fe97130246bfd2cf5fd9e84 (MD5) Previous issue date: 2012-07-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The present study was developed in order to evaluate the effects of three plant species extracts on the leaf-cutting ant Atta sexdens rubropiloa colonies. We used leaves of Ageratum conyzoides ( mentrasto ), Coriandrum sativum (coriander) and Mentha piperita (peppermint) species. The activities were conducted at the Federal University of Viçosa campus, in Viçosa-MG. First, we evaluated the effects of these plant extracts on workers physiology, through the immune response and respiratory metabolism. The extracts of coriander and mentrasto had an effect on the ants physiology. The workers increased their immune response when treated with the coriander extract. The mentrasto extract increased the respiratory metabolism of the ants. In another step, we investigated the effect of the extracts on the development of Leucoagaricus gongylophorus, the symbiotic fungus of leaf-cutting ants. It was found that the three extracts adversely affected the fungus growth causing complete inhibition of its development. The best performances were obtained with peppermint and mentrasto extracts that caused high reduction in the biomass of L. gongylophorus even at lower concentrations. Finally, we evaluated the mortality of ant nests after offering baits manufactured with leaves of the three plant species. The results indicated that the baits were unable to cause colony mortality. However, it was found that the treated nests stopped their cutting activity, suggesting baits´ effect on the colonies. Therefore A. conyzoides, C. sativum and M. piperita have deleterious effects on Atta sexdens rubropilosa colonies, and may be promising on the leaf-cutting ants control. / Este estudo foi desenvolvido a fim de se conhecer os efeitos de extratos de três espécies vegetais sobre colônias da formiga-cortadeira Atta sexdens rubropilosa (saúva-limão). Foram usadas folhas das espécies Ageratum conyzoides (mentrasto), Coriandrum sativum (coentro) e Mentha piperita (hortelã). As atividades foram realizadas no campus da Universidade Federal de Viçosa, na cidade de Viçosa-MG. Primeiramente, foram avaliados os efeitos do extrato hexânico dessas plantas na fisiologia das operárias da formiga-cortadeira, através de sua resposta imune e de seu metabolismo respiratório. Os extratos de coentro e mentrasto apresentaram efeito na fisiologia das formigas. As operárias tiveram elevação de sua resposta imune, quando tratadas com o extrato de coentro. O extrato de mentrasto aumentou o metabolismo respiratório das formigas. Em outra etapa, foi investigado o efeito do extrato dessas plantas sobre o desenvolvimento de Leucoagaricus gongylophorus, o fungo simbionte das cortadeiras. Constatou-se que os três extratos afetaram negativamente o crescimento do fungo, causando completa inibição do seu desenvolvimento. Os melhores desempenhos foram obtidos com os extratos de hortelã e de mentrasto, que mesmo nas menores concentrações causaram elevada redução na biomassa de L. gongylophorus. Finalmente, foi avaliada a mortalidade de formigueiros de saúva-limão após oferecimento de iscas confeccionadas a base de folhas das três espécies de plantas. Os resultados indicaram que as iscas não foram capazes de causar mortalidade das colônias. Entretanto, verificou-se que os formigueiros tratados tiveram sua atividade de corte paralisada, indicando efeito das iscas sobre as colônias. Conclui-se, assim, que as espécies A. conyzoides, C. sativum e M. piperita apresentam efeitos deletérios sobre as colônias de A. sexdens rubropilosa, sendo promissoras no controle de formigas-cortadeiras.

Dando continuidade a uma pesquisa estética iniciada em 1991, este projeto de pesquisa em arte propõe a realização da série FORMIGAS, e o texto desta dissertação trata das relações entre a ética e a estética que essa obra estabelece ao longo dos quatro anos de duração do seu processo instaurador. No decorrer desse período, uma primeira versão dessa mesma série, composta por uma seqüência de nove eletrongrafias de caras de formigas de várias espécies, gerou um impasse ético que a presente versão, composta por uma seqüência de quinze eletrongrafias de caras de formigas do gênero acromyrmex, propõe discutir e contornar. / The current paper is a research project in art that discusses the relation between the ethics and the aesthetics brought about by the making of the ANT series. It is part of an aesthetic investigation initiated in 1991 and the series instauration process has taken four years. A first version of the series was composed by a sequence of nine electrongraphs of ant faces of several species, and the second version is composed by fifteen electrongraphs of ant faces of the genus acromyrmex. The first version raised an ethical dilemma which the second one and this paper are meant to discuss and resolve.

The thesis focuses on the study of arboreal ant communities in a highly diverse tropical rainforest in Papua New Guinea. In the first study of its kind, whole patches of forest were sampled extensively for ants foraging and nesting in tree trunks and canopies. An extraordinary amount of material collected from 684 felled trees and 260 bait stations in plots of primary and secondary forest was used to study the mechanisms structuring the diversity and species coexistence of this ecologically important insect group at the local scale. The first chapter addresses the question "Why are ant communities more species rich in primary than in secondary forests?" and explores the main environmental traits that influence their diversity in tropical trees. The second chapter compares the community diversity and composition and nesting preferences of ant species between both forest types. The final third chapter introduces a novel method, involving large-scale manipulation of ant communities that could serve as a template for future studies focused on complex tropical food-webs of canopy arthropods and plants. In summary, the results of the thesis highlight the importance of primary vegetation in conserving the diversity of native ant communities and the relevance of nesting microhabitats and their turnover between trees, rather than tree taxonomic diversity, for sustaining the diverse arboreal fauna in tropical forests.

Made available in DSpace on 2015-03-26T13:30:29Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1918178 bytes, checksum: 241cb304c0bcc9754ca950637f38d713 (MD5) Previous issue date: 2010-07-26 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Forest fragmentation events have been characterized as one of the main threats to biodiversity in modern times, and are the primary cause of species loss in tropical forests. Ants are organisms that present many suitable traits to be used in ecological studies, therefore they are frequently used in fragmentation surveys. However only epigaeic microhabitat have been considered in these studies, neglecting other important microhabitats. Hence, with this study we aimed to answer the following question: Why are there more ant species in forest remnants compared to matrices? We made explanatory hypotheses, in which environmental variables were taken as surrogates of resources and conditions. The study was carried out in four forest remnants and four surrounding matrices in Viçosa municipality, Minas Gerais state, Brazil. Ants were sampled with pitfall traps in two microhabitats, epigaeic and hypogaeic, with unbaited pitfall traps. The diversity was partitioned, following the equation γ = α + β. An ANOVA was made at each scale to test the assumption that fragment harbour more species than matrices. Explanatory variables were analysed through hierarchical partitioning to find out which variables are more important in explaining species richness and using GLM to depict the relationships among variables. Estimators of species richness were employed to asses the effect of fragmentation in the landscape. Species composition was tested through NMDS and significance values were obtained by ANOSIM. We confirmed our assumption only for β and γ diversity. The most important variables to explain diversity were %Sand (-), CEC (+), iron concentration (-) and soil organic matter (unimodal). Variation among environmental parameters in relation to fragmentation explained the variations in species richness. We found differences in species composition, with forest habitats being distinct from matrices at both epi- and hypogaeic microhabitats. A distinction between epigaeic/hypogaeic communities was found only in forest environments. We confirmed our assumption and confirmed that some variables are important for explaining species loss caused by fragmentation. It give support to the fact that alterations caused on environmental quality are important and must beconsidered. Moreover, species composition revealed that there are specific subsets in each local, matrices and forests. Still, the lack of difference in species composition between microhabitats in matrices reveals the strong effect of fragmentation on some hypogaeic species, that should depend on litter, that is not available after vegetation clearance. / Eventos de fragmentação florestal são caracterizados como uma das maiores ameaças à biodiversidade e são a causa primária de perda de espécies nas florestas tropicais. Formigas são organismos que apresentam diversas características favoráveis ao seu uso em trabalhos ecológicos, o que as torna frequentes em estudos sobre fragmentação. Portanto, o objetivo deste estudo é responder a seguinte pergunta: Por que há mais espécies de formigas nos fragmentos florestais em relação ao entorno? Para responder a essa questão, hipóteses explicativas foram lançadas, baseadas em recursos e condições. Além disso, diferenças nas respostas em diferentes microhabitats foram analisadas. A amostragem foi realizada em quatro fragmentos florestais e quatro entornos adjacentes na cidade de Viçosa, Minas Gerais, Brasil. As formigas foram amostradas nos microhabitats epi- e hipogéicos, com armadilhas pitfall sem iscas. Foram coletadas amostras de solo para obter variáveis explicativas. A diversidade de formigas foi particionada seguindo a equação γ = α + β. O pressuposto, de que o fragmento é mais diverso que o entorno foi testado através de ANOVA. As variáveis explicativas foram testadas através de partição hierárquica, para detectar as variáveis mais importantes na explicação da diversidade e estas variáveis foram testadas através de glm para demonstrar a relação e a tendência. Estimativas de riqueza de espécies foram realizadas para se estimar o efeito na escala de paisagem. A composição de espécies foi testada através deNMDS, e a significância acessada através de ANOSIM. Nosso pressuposto se confirmou apenas a nas escalas de diversidade β e γ e para o hábitat epigéico. Além disso, as variáveis mais importantes para explicação foram %areia (-); CTC (+); concentração de ferro (-)e matéria orgânica do solo (unimodal). Além disso, estas variáveis apresentam o mesmo padrão de variação que o pressuposto, sendo fortes candidatas a fatores causais. A composição de espécies variou, sendo distinta quando comparamos fragmento vs. entorno e quando comparamos entre microhabitats epi- e hipogéicos. No último, observamos resposta apenas para o ambiente florestal. A confirmação do nosso pressuposto, bem como a explicação provida pelas variáveis ambientais suportam o fato de que alterações causadas na qualidade do ambiente pela fragmentação são responsáveis pela perda de espécies observada. Ainda, a composição de espécies revelou que existem subconjuntos de espécies específicos de cada local, matrizes e florestas. Ainda, a ausência de diferença na composição de espécies entre os microhabitats na matriz revela uma acentuada perda de algumas espécies que existiam no ambiente florestal, mas que não mais estão presentes.

Made available in DSpace on 2016-06-02T20:34:44Z (GMT). No. of bitstreams: 1 5260.pdf: 14825689 bytes, checksum: b6506c8cf1982938a8e81b800ba1089e (MD5) Previous issue date: 2013-03-22 / Universidade Federal de Minas Gerais / The leaf-cutting ants of the genera Atta and Acromyrmex are considered between the most important plagues in agriculture, grassland and reforestation program, due the great amount of leaves cut which the plants are submitted. The factors such as natural resources abundance as food source, scantiness of natural enemies and competitions among others species, promote the attack and, consequently, damages to the plantation, generating serious economic damages, since the density of the nests of leaf-cutting ants can increase 5 to 10 times in relation to a nest in natural environment. The Sapindales order is composed by the families Staphyceaceae, Melianthaceae, Bretschneideraceae, Akaniceae, Sapindaceae, Hippocastanaceae, Aceraceae, Burseraceae, Anacardiaceae, Julianiceae, e Zygophyllaceae. Several compounds with insecticide and antifungal activities have been gotten from these families. In this context, the present work aimed as main objectives the bio-monitored phytochemistry study of Picramnia bahiensis and Thyrsodium schomburgkianum to obtain natural insecticides against Atta sexdens rubropilosa and/or fungicides against the symbiotic fungus Leucoagaricus gongylophorus and, specially, the study of methodologies to apply them to their control. The phytochemistry study of these plants allowed the isolation and identification of 24 compounds, acids and esters that have long chain, anthraquinones, steroids and terpenoids, many of them were identified using the Mass Spectrometry technique (HPLC/ESI-MS/MS), being that the substances 11 and 12 are previously unpublished in literature. Among these substances, chrysophanol, isolated from the roots of P. bahiensis, stand out to have potential insecticide and fungicide activities against the leaf-cutting ants. Furthermore, the study was extended with similar commercial compounds, leading to the compound menadione, also with both potential activities. This fact led to development of formulations through the nanoencapsulation process in order to, besides to obtain highly active compounds, develop an application methodology of them, thus providing an insecticide and fungicide that is viable to use in the leaf-cutting ants control. Therefore, these insecticides have been nanoformulated first time in the literature by the nanoencapsulation technique, evaluating properties such as, for example, the delay activity compared to the free compounds, increasing their effectiveness. Additionally, the analytical method was validated via HPLC, following the ANVISA rules, aiming, mainly, reliability of the quantification results for comparison with traditional standards of baits in the market. / As formigas-cortadeiras dos gêneros Atta e Acromyrmex são consideradas as mais importantes pragas na agricultura, pastos e programas de reflorestamento devido ao desfolhamento causado pela descontrolada herbivoria que as plantas são submetidas. Os fatores como abundância dos recursos naturais como fonte de alimentos, escassez de inimigos naturais e competições entre outras espécies, promovem o ataque e, consequentemente, danos à plantação, gerando sérios prejuízos econômicos, já que a densidade dos ninhos de formigas-cortadeiras pode aumentar de 5 a 10 vezes em relação a um ambiente de equilíbrio ecológico. A ordem Sapindales é composta pelas famílias Staphyceaceae, Melianthaceae, Bretschneideraceae, Akaniceae, Sapindaceae, Hippocastanaceae, Aceraceae, Burseraceae, Anacardiaceae, Julianiceae, e Zygophyllaceae. Dentro destas famílias, diversos compostos com atividade inseticida e fungicida têm sido obtidos. Neste contexto, o presente trabalho teve como objetivos principais o estudo fitoquímico biomonitorado de Picramnia bahiensis e Thyrsodium schomburgkianum na obtenção de produtos naturais inseticidas (frente à Atta sexdens rubropilosa) e/ou fungicidas (frente ao fungo simbionte Leucoagaricus gongylophorus) e, principalmente, o estudo de metodologias de aplicação dos compostos bioativos para o seu controle. Assim, o estudo fitoquímico das plantas supracitadas permitiu o isolamento e identificação de 24 compostos, ácidos e ésteres de cadeia longa, antraquinonas, esteróides e terpenos, muito deles sendo identificados através da técnica de Espectrometria de Massas (HPLC/ESI-MS/MS), sendo que as substâncias 11 e 12 são inéditas na literatura. Dentre estes compostos, crisofanol, isolada das raízes de P. bahiensis, se destacou por apresentar atividade inseticida e fungicida em potencial frente às formigas-cortadeiras. Além disso, o estudo foi ampliado com compostos comerciais similares, levando ao composto menadiona, também com ambas as atividades em potencial. Este fato levou ao desenvolvimento de formulações através do processo de nanoencapsulamento no intuito de, além de obter compostos altamente ativos, desenvolver uma metodologia de aplicação dos mesmos, fornecendo assim um inseticida e fungicida que sejam viáveis no uso para o controle das formigas-cortadeiras. Assim, estes formicidas foram, pela primeira vez na literatura, nanoformulados através da técnica de nanoencapsulamento, avaliando propriedades, como por exemplo, o prolongamento da atividade frente aos compostos livres, melhorando assim sua eficácia. Além disso, todo o método analítico foi validado via HPLC, seguindo as normas da ANVISA, visando, principalmente, a confiabilidade nos resultados de quantificação para a comparação com padrões de iscas tradicionais existentes no mercado.