No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

The American cockroach, Periplaneta americana (L.), is an important urban pest due to its ability to invade residential and commercial structures from non-residential reservoirs. Extensive field studies were conducted in a large urban apartment complex, Lincoln Terrace (LT), managed by the Roanoke Redevelopment and Housing Authority (RRHA), in Roanoke, Virginia. Inspection in the RRHA-LT complex corroborated well with other researchers' finding that sewer and storm drainage systems are the principal reservoirs for P. americana population in the temperate urban environn1ent. Investigations provided new evidence that basements of the RRHA-LT apartment buildings served as secondary reservoirs for this pest species. Environmental and ecological parameters that characterize basements as important P. americana population reservoir foci were studied. Understanding how populations function in the urban environment is as important as identifying P. americana population reservoirs. Over two-years of fleld investigations demonstrated that foraging activity of P. americana was seasonal. A study of a simulated population of caged American cockroaches maintained in a basement environment confirmed that their foraging activity was seasonal. Foraging seasonality characterizes the seasonal pest status of this cockroach species in the temperate urban environment. Therefore, seasonally oriented control or management strategies for this pest species are proposed and discussed. Lipids, carbohydrates, and proteins of American cockroach adults were analyzed and quantified on a monthly basis for a year. Seasonal foraging activity was reflected by seasonal changes of metabolic reserves in this species. Low foraging activity in the colder, winter months characterized an overwintering period of P. americana populations in the urban environment. Lipids were the principal metabolic reserve for overwintering cockroaches, and accounted for a 22% of dry body weight loss in females and 18% in males. Proteins accounted for approximately 10% of the dry body weight loss for overwintering females and males. Glycogen concentration per unit dry weight increased 11 % to 15% during the overwintering period. This change suggests that glycogen may function as a cold hardiness substance rather than as a energy reserve during overwintering. Nutrient deficits of post-overwintering individuals in the population explained the underlying physiological driving force for significantly ir~creased foraging activities in the spring. Caged P. americana demonstrated a high reproductive potentia] in the basement environment. High reproductive rate created protein and lipid deficits in adults that required increased foraging for food and increased cannibalism of oothl!cae and young nymphs. Approximately 33% of the oothecae and 28% of nymphs were cannibalized in the caged population. / Ph. D.

En milieu naturel, la vie en société implique que de nombreuses actions, activités ou décisions soient réalisées en groupe. Dans la littérature, nous retrouvons un certain nombre de définitions concernant ces décisions collectives, mais très peu de travaux se sont intéressés aux mécanismes gouvernant l'apparition de ces formes de coopération. En particulier, l'étude d'espèces d’arthropodes sociaux ou grégaires a été délaissée au profit des espèces eusociales et des groupes de vertébrés. <p><p>Ce travail de thèse repose sur un ensemble d'expériences et de modélisations destinées à approfondir notre compréhension des mécanismes gouvernant les décisions collectives chez les insectes grégaires. Pour mener à bien ce travail, nous avons quantifié les réponses individuelles et collectives chez la blatte Periplaneta americana, dans un milieu caractérisé par la présence de sites de repos (de qualité identique ou différente). Il s'agit de comprendre et de caractériser les différentes dynamiques qui, sur base des préférences individuelles pour les différents sites de repos et des interactions sociales, permettent à l'échelle de la population l'émergence d’un choix collectif, et au niveau individuel, à l’exploitation optimale de son environnement. <p><p>Nos résultats ont montré que malgré l'absence de communication ou de perception à longue distance (ex :orientation visuelle, phénomènes de suivi de piste), sans comparaison ni connaissance parfaite du milieu (ex :la localisation et le nombre d’abris ou de congénères) les blattes sont capables de discriminer collectivement entre des alternatives spatialement dispersées et de faire le meilleur choix (associé au maintien de la cohésion). Ce phénomène de choix collectif est un sous-produit des différentes dynamiques agrégatives gouvernées par les compétitions entre processus d’amplification et permet au groupe de résoudre un problème qui est au-dessus des capacités individuelles. Dans nos expériences, cela se manifeste par une double augmentation en fonction de la taille du groupe: (1) un individu tend à s'installer plus souvent dans un site de repos et (2) un individu a plus de chances de se retrouver sous le site de repos optimal. Une analyse plus fine des comportements individuels, rendue possible par l'utilisation de la RFID, a montré qu’au sein des blattes, deux stratégies existaient: les initiateurs et les explorateurs. Enfin, l'utilisation de robots (sociétés mixtes blattes/robots) nous a permis de valider notre modèle théorique mais aussi d’introduire artificiellement des conflits d'intérêt entre les membres du groupes :la présence de ces individus clefs peut modifier la réponse collective de manière dramatique.<p><p>Après avoir comparé nos travaux avec la littérature actuelle, nous avons discuté de la valeur générique de tels processus agrégatifs, prérequis essentiel pour la coordination et la synchronisation des activités des individus. L'agrégation constitue une des conditions nécessaires et indispensables à l'apparition d’une vie sociale permettant le développement d’une coopération plus élaborée.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Endosymbiosis is a pervasive phenomenon that has been a powerful force in insect evolution. In many well studied insect-bacterial associations, the bacteria can serve as reproductive manipulators, nutritional mutualists or defenders of their hosts. Fungi are also frequently associated with insects, and initial estimates suggest that these fungi are hyperdiverse. Saving a handful of examples, however, the functions of these fungi within insect hosts are largely unknown. This dissertation begins with a review that lays the conceptual groundwork for understanding bacterial and fungal endosymbiosis in insects. I make predictions about why one versus the other microbe might serve the insect, given any unique physiological, ecological or evolutionary conditions. I then aim to derive insights about microbial symbiosis by focusing on a particular system, that of brownbanded cockroaches, Supella longipalpa (Blattaria: Blattellidae) and their specialist wasp parasitoids, Comperia merceti (Hymenoptera: Encyrtidae). Here, I identify the symbiotic community of these two insects by using both culture-dependent and independent methods to characterize the vertically transmitted bacterial and fungal associates. Finally, I show that a heritable fungus in C. merceti, long presumed to be a mutualist, is parasitic under laboratory conditions: infected wasps incur fitness costs for housing the fungal symbiont relative to uninfected wasps. Additionally, although the fungus is not horizontally transmitted sexually, it is readily horizontally transmitted from the offspring of infected females to those of uninfected females that are using the same host.

Bases para a implementação de um programa de manejo da resistência de Blattella germanica (L.) a inseticidas foram coletadas no presente trabalho. Técnicas de bioensaio de aplicação tópica e de contato tarsal foram comparadas inicialmente para a detecção da resistência a deltametrina e clorpirifós. O bioensaio de aplicação tópica possibilitou uma melhor discriminação entre a linhagem suscetível e as populações de campo de B. germanica testadas. Resultados do monitoramento da suscetibilidade de B. germanica a inseticidas evidenciaram a presença de variabilidade genética que confere resistência a deltametrina, clorpirifós e fipronil em populações coletadas em alguns estabelecimentos comerciais dos Estados de São Paulo e Rio de Janeiro. As razões de resistência encontradas para deltametrina e clorpirifós foram de aproximadamente 43 e 6 vezes, respectivamente. A resistência de B. germanica a deltametrina foi instável, ou seja, houve uma redução significativa na freqüência de resistência na ausência de pressão de seleção. Estudos de relações de resistência cruzada revelaram uma baixa intensidade de resistência cruzada (aproximadamente 2 vezes) entre fipronil e os inseticidas deltametrina e clorpirifós. E por último, a mistura de deltametrina e clorpirifós foi avaliada para o controle de linhagens de B. germanica resistentes a deltametrina. A mistura proporcionou um melhor controle da linhagem suscetível do que os produtos utilizados isoladamente. No entanto, a discriminação entre as linhagens suscetível e resistente a deltametrina foi evidente com a mistura nas doses recomendadas comercialmente, o que inviabilizaria o emprego desta estratégia no manejo da resistência de B. germanica a deltametrina. / Bases for implementing a resistance management program of Blattella germanica (L.) to insecticides were collected in this study. Initially, we compared the topical and residual tarsal-contact bioassays for detecting resistance to deltamethrin and chlorpyrifos. The topical bioassay gave better discrimination between susceptible and field-collected populations of B. germanica. Results from a survey of the susceptibility of B. germanica to insecticides revealed the presence of genetic variability that confers resistance to deltamethrin, chlorpyrifos and fipronil in field-collected populations of B. germanica from the States of São Paulo and Rio de Janeiro. The resistance ratios to deltamethrin and chlorpyrifos were approximately 43 and 6-fold, respectively. The resistance of B. germanica to deltamethrin was unstable; that is, a significant reduction in the frequency of resistance was detected under absence of selection pressure. Studies on cross-resistance relationships showed a low intensity of cross-resistance (approximately 2-fold) between fipronil and the insecticides deltamethrin and chlorpyrifos. And finally, the viabilility of the use of deltamethrin and chlorpyrifos mixture was evaluated for controlling deltamethrin-resistant strains of B. germanica. The use of mixtures gave better control of the susceptible strain than the use of the products by itself. However, the discrimination between susceptible and resistant strains was clear with the use of mixtures at recommended rates, which impairs the use of this strategy for managing B. germanica resistance to deltamethrin.