Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Understanding the impact of environmental factors on locomotor performance and flight energetics is of fundamental importance to understanding evolution and ecology. Increased performance that leads to increased dispersal ability can result in increased migration distance to reach optimal habitats, increased gene flow between populations and an overall contribution to the survival of individuals as well as the structuring of species‟ geographic range sizes. The temperature-dependent nature of insects, in conjunction with predicted climate change and shifting optimal climatic ranges, could have important ecological and economic consequences such as increased invasion by alien and pest species. In this study, the influence of thermal history on temperature-dependent flight performance was investigated in a notorious invasive agricultural pest, Ceratitis capitata (Diptera: Tephritidae). Flies were exposed to one of four developmental acclimation temperatures (Tacc: 15, 20, 25, 30°C) during their pupal stage and tested at random at either of those temperatures (Ttest) as adults in a full-factorial experimental design. Major factors influencing flight performance included sex, body mass, Ttest and the interaction between Ttest and Tacc. Performance increased with increasing Ttest across all acclimation groups, e.g. at 15°C only 10% of all flies had successful flight, whereas at 30°C the success rate was 76.5%. Even though Tacc alone did not affect flight performance, it did have an effect in combination with Ttest. The negative interaction term Ttest x Tacc, in combination with a multiple comparison between Tacc groups at each Ttest, indicated that flies acclimated to 15°C and 20°C performed better than those acclimated to 25°C and 30°C when tested at cold temperatures. This provides partial support for the "colder is better‟ hypothesis. To explain these results, several key, flight-related traits were examined to determine if Tacc influenced flight performance as a consequence of changes in body or wing morphology, whole-animal metabolic rate or cytochrome c oxidase (CCO) activity. Although significant effects of Tacc could be detected in several of the traits examined, with emphasis on sex-related differences, increased flight performance could not be explained solely on the basis of changes in any one of these traits. To illustrate the potential applied value of this study, the main flight performance outcomes were also coupled with a degree-day (thermal development) model to determine if knowledge of flight ability could improve predicted population dynamics. The results and insights obtained from this study are broadly applicable to a variety of insect species and demonstrate that, by recognising the impact of environmental factors on locomotor performance and flight energetics, an increased understanding of the functioning, biology and evolution of flight-capable arthropods can be obtained. / AFRIKAANSE OPSOMMING: Groter begrip van die impak van omgewingsfaktore op bewegingsprestasie en vlug-energetika is van fundamentele belang vir die verstaan van evolusie en ekologie. Verhoogde bewegingsprestasie wat lei tot verbeterde verspreidingsvermoë kan 'n toename in migrasieafstand om optimale habitat te bereik, verhoogde genevloei tussen populasies en ʼn algehele bydrae tot die oorlewing van individue sowel as die strukturering van spesies se geografiese gebiedsgroottes tot gevolg hê. Die temperatuurafhanklike aard van insekte, tesame met voorspelde klimaatsverandering en die verskuiwing van optimale klimaatsones, kan belangrike ekologiese en ekonomiese gevolge, soos verhoogde indringing deur uitheemse en pes-spesies, inhou. Die invloed van termiese geskiedenis op die temperatuurafhanklike vlugprestasie van 'n berugte indringer-landboupes, Ceratitis capitata (Diptera: Tephritidae), word in hierdie studie ondersoek. Vlieë is blootgestel aan een van vier akklimasie-temperature (Tacc: 15, 20, 25, 30°C) tydens hul papiestadium en is op ewekansige wyse in 'n vol-faktoriale eksperimentele ontwerp by een van dieselfde toetstemperature (Ttest) as volwassenes getoets. Belangrike faktore wat vlugprestasie beïnvloed het, sluit geslag, liggaamsmassa, Ttest en die interaksie tussen Ttest en Tacc in. Prestasie het verbeter met toenemende Ttest oor al die akklimasiegroepe, bv. by 15°C het net 10% van alle vlieë suksesvol gevlieg, terwyl die sukseskoers by 30°C, 76,5% was. Selfs al het Tacc alleen nie die vlugprestasie beïnvloed nie, het dit 'n effek in kombinasie met Ttest gehad. Die negatiewe interaksie term Ttest x Tacc, in samewerking met 'n meervoudige vergelyking tussen Tacc groepe by elke Ttest, het aangedui dat vlieë wat by 15°C en 20°C geakkimeer was, beter presteer het as dié wat by 25°C en 30°C geakklimeer was wanneer hulle by koue temperature getoets was. Dit bied gedeeltelike ondersteuning vir die "kouer is beter" hipotese. Om hierdie resultate te verklaar, is 'n paar sleutel vlugverwante eienskappe ondersoek om te bepaal of Tacc vlugprestasie a.g.v. veranderinge in die liggaam- of vlerkmorfologie, die hele-dier metaboliesetempo of sitochroom-c oksidase (CCO) aktiwiteit beïnvloed. Alhoewel beduidende effekte van Tacc op verskeie van hierdie eienskappe, veral wat geslagsverwante verskille betref, opgemerk is, kan verhoogde vlugprestasie nie uitsluitlik op grond van veranderinge in enige een van die eienskappe verduidelik word nie. Om die potensiële toepassingswaarde van hierdie studie te illustreer, is die hoof vlugprestasie uitkomste gekoppel aan 'n “degree-day” (termiese ontwikkeling)-model om te bepaal of kennis van vlugvermoë voorspellings van bevolkingsdinamika kan verbeter. Hierdie studie se resultate en insigte is oor die algemeen van toepassing op 'n verskeidenheid insek-spesies en toon dat erkenning van die invloed van omgewingsfaktore op bewegingsprestasie en vlug-energetika kan lei tot groter begrip van die funksionering, biologie en evolusie van geleedpotiges.

La localisation des plantes-hôtes est un processus déterminant dans la stratégie adaptative des insectes phytophages et les stimuli olfactifs, qui sont des composés volatils émis par les plantes, jouent un rôle essentiel dans ce processus. Bactrocera cucurbitae (Diptera, Tephritidae) est responsable d'importants dégâts sur maintes cultures maraîchères à l'échelle mondiale et à La Réunion. Si la bio-écologie et la structuration génétique des populations de cette espèce sont relativement bien connues, des connaissances sur la médiation chimique se produisant lors de la localisation des fruits-hôtes restent nécessaires pour améliorer la gestion des populations de cette espèce. L'objectif de la thèse est de caractériser les stimuli olfactifs impliqués dans la localisation à distance par les femelles de B.cucurbitae, d'une large gamme de fruits-hôtes de Cucurbitaceae sauvages et cultivées de La Réunion. Une approche bidisciplinaire (comportementale et chimique) a été adoptée afin d'identifier, parmi 27 fruits-hôtes, les composés volatils responsables de l'attraction des femelles vers leurs sites de ponte. Les résultats soulignent, qu'au sein de la gamme de plantes-hôtes, la réponse des femelles aux effluves de ces fruits est très hétérogène (taux d’attraction de 1 % à 74 %), variant selon l'espèce végétale, la variété et le stade de maturité des fruits. Parallèlement, l'étude de la composition chimique des effluves de ces fruits révèle une chimiodiversité inter- et intraspécifique considérable : 280 composés volatils identifiés au total, avec des profils d'émission différents d'un fruit à l'autre. Ces résultats, complétés par de l’électroantennographie couplée à la chromatographie gazeuse, ont permis de déterminer 34 composés potentiellement impliqués dans l'attraction des femelles. De plus, un mélange à deux composés volatils de synthèse, aussi attractif qu'une odeur de fruits frais, a été identifié à partir des réponses des femelles à 10 des 34 composés, présentés individuellement ou en mélange. Les rôles des composés volatils de fruits-hôtes dans le processus de localisation des sites de ponte et dans la spécialisation écologique de cette espèce de ravageurs sont discutés. Par ailleurs, l'association des résultats de préférence des femelles et de performance larvaire représente une perspective de recherche prometteuse, qui contribuerait à acquérir une connaissance plus fine du phénomène de spécialisation d'hôte. Enfin, il est désormais possible d'envisager l'utilisation du mélange simple à deux composés volatils dans un système de piégeage des femelles, à intégrer dans un schéma de gestion agroécologique des populations de B. cucurbitae. / Locating host-plants is a key process in the adaptive strategy of phytophagous insects, and olfactory stimuli, which arevolatile compounds emitted by plants, play an essential role in this process. Bactrocera cucurbitae (Diptera,Tephritidae) is responsible for significant damage to many vegetable crops in Reunion Island and worldwide. Whilethe bioecology and genetic population structure of this species are relatively well known, understanding the chemicalmediation occurring during host-fruit location is needed to improve the management of this pest. The aim of this thesis is to characterize the olfactory stimuli involved in the location by females of B. cucurbitae, of awide range of wild and cultivated host fruits of Cucurbitaceae in Reunion Island. A multidisciplinary approach (behavioural and chemical) was adopted to identify volatile compounds responsible for the attraction of females to their oviposition sites in 27 host fruits. The results highlight that within the range of host plants the female response to fruit odours is very heterogeneous(attraction rates from 1% to 74%). These levels of female response vary according to the plant species and the varietyand the stage of fruit maturity. Meanwhile, the study of the chemical composition of fruit odours reveals aconsiderable inter- and intraspecific chemodiversity: 280 volatile compounds identified in total, with differentemission profiles from one fruit to another. These results, complemented by coupled gas chromatographyelectroantennographic detection, have identified 34 compounds potentially involved in female attraction. In addition, ablend of two synthetic compounds as attractive as fresh fruit odour was identified by measuring attractiveness of 10 ofthe 34 compounds presented individually or in combination. The roles of volatiles in oviposition sites location and ecological specialization of this pest are discussed. Moreover,the association of these results with data on female preference and larval performance represents a promising researchdirection, which would contribute to a better understanding of the phenomenon of host specialization. Finally, theintegration of a simple two-component blend in a trapping system for females into an agroecological management scheme for B. cucurbitae populations is proposed.

Malgré les procédures de quarantaine, de nombreuses invasions par des mouches des fruits polyphages (famille des Tephritidae) ont été observées dans différentes parties du monde. Dans cette étude les paramètres démographiques, des co-infestations expérimentales dans un même fruit et l'interférence entre femelles adultes sont comparés entre quatre espèces de Tephritidae : trois espèces invasives qui se sont installées successivement à La Réunion et une espèce endémique de cette île. Les résultats suggèrent un trade-off interspécifique entre les traits K et r. La compétition larvaire a un effet négatif sur le poids pupal et la survie larvaire. Chez les femelles adultes, des comportements d'expulsion loin du fruit par d'autres femelles ont été observés. L'asymétrie de la compétition larvaire et des interactions directes entre femelles semble corrélée au rang d'établissement sur l'île, l'espèce arrivée la plus récemment ayant de bonnesperformances dans la compétition larvaire comme dans l'aptitude à déplacer d'autres femelles d'un fruit. La coexistence entre espèces est cependant permise par la variabilité de la tolérance aux conditions climatiques (température et humidité) et par celle de la gamme d'hôtes. L'espèceendémique a non seulement de plus faibles paramètres de survie et de fécondité que les autres espèces mais voit également les axes climatiques et de ressource de sa niche inclus dans celles de ses compétiteurs. Une coexistence stable devrait s'installer entre les trois espèces invasives alors que l'extinction de l'espèce endémique est considérée comme possible.

Thesis (Ph.D. (Zoology & Entomology)) - Rhodes University, 2009.

Made available in DSpace on 2016-06-02T20:21:28Z (GMT). No. of bitstreams: 1 4084.pdf: 6015722 bytes, checksum: 35112ba46f0915602cf01b2a6f292699 (MD5) Previous issue date: 2011-12-19 / Universidade Federal de Minas Gerais / The Tephritidae includes approximately 4500 species described to date and many of these species make up the main genera of economic importance: Anastrepha, Bactrocera and Ceratitis. The genus Anastrepha is among the Tephritidae with greatest diversity in the Americas including 230 described species, among which some species with great economic importance because they represent important fruit pests. There is evidence that species in the fraterculus group have diverged recently, even having some cryptic species. Because of this, species in the fraterculus group are a great system for evolutionary studies. For evolutionary studies, it is necessary to evaluate the rates of molecular evolution and their role in identifying rates of gene flow and population differentiation, the construction of tree species and a possible separation for the species. Seeking a better understanding of the fraterculus group, we chose three species of this group, Anastrepha obliqua, A. fraterculus and A. sororcula as models for this study and five genes isolated from a cDNA library of reproductive tissues of Anastrepha. Several genes that are expressed in reproductive tissues have a higher divergence rate THAN those expressed in non-reproductive tissues, may thus give evidence of reproductive isolation. In this work, we found evidence of positive diversifying and positive selection for a couple of genes (CG11912 and CG10031), and high levels of polymorphism, although they failed to meet statistical significance for positive selection, in other genes here studied, such as ,Lcp65Ac and CG16712, whereas Df31 was more conserved. An analysis of molecular variance found that levels of genetic polymorphism are best explained by differences between species THAN between geographic regions. Haplotype networks for each gene failed to differentiate the species here studied and showed high levels of shared polymorphism among the species, with some rare exceptions. On the other hand, a joint analysis of these data to try to infer a species tree indicate a strong cohesion for populations of A. obliqua from the Brazilian Northeast and Southeast while for A. fraterculus and A. sororcula we observed a substructure that separated Southeeast populations of A. sororcula, which was well defined, from Northeast populations, which may be hybridizing with populations of A. fraterculus from the Northeast, due to great number of shared polymorphisms. Other THAN populations in the Brazilian northeast, A. fraterculus also forms a separate, though short, lineage. Considering these findings, a broader sampling is needed, especially in areas not yet collected particularly in the Northeast, seeking to untangle the phylogenetic relationships not only among these species, but also other species of the fraterculus group. / Os Tephritidae incluem aproximadamente 4500 espécies já descritas e muitas destas espécies compõem os principais gêneros de importância econômica: Anastrepha, Bactrocera e Ceratitis. O gênero Anastrepha é, entre Tephritidae, o que possui maior diversidade nas Américas incluindo 230 espécies descritas, dentre as quais algumas espécies apresentam grande importância econômica por representarem importantes pestes da fruticultura. Há evidências de espécies que constituem o grupo fraterculus terem divergido há pouco tempo apresentando ainda algumas espécies crípticas. Devido a esta característica em particular, espécies do grupo fraterculus apresentam uma grande vantagem para estudos evolutivos. Para realizar estudos evolutivos torna-se necessário avaliar as taxas de evolução molecular bem como seu papel na identificação de taxas de fluxo gênico e diferenciação populacional, a construção de árvores de espécie e uma possível separação das espécies. Buscando um melhor entendimento do grupo fraterculus, escolhemos três espécies constituintes desse grupo, Anastrepha obliqua, Anastrepha. fraterculus e Anastrepha. sororcula, como modelos para este estudo e cinco genes isolados de biblioteca de cDNA de tecidos reprodutivos de espécies de Anastrepha. Diversos genes que são expressos em tecidos reprodutivos apresentam uma taxa de divergência maior do que os expressos em tecidos não reprodutivos, podendo assim dar indícios de isolamento reprodutivo. Neste trabalho encontramos essas características em genes que indicam seleção positiva (CG11912 e CG10031), e os demais genes que embora não tenham apresentado significância estatística para serem considerados possuidores de seleção positiva, no entanto apresentam terem regiões potencialmente sob seleção positiva direcional para Df31 e Lcp65Ac e seleção positiva diversificadora para os genes Df31 e CG16712. Na análise de variância molecular encontramos que a diferenciação espacial é mais bem explicada pelas diferenças entre as espécies do que entre regiões geográficas. As redes haplotípicas e árvores de espécies indicam uma forte coesão entre as populações de A. obliqua do Nordeste e Sudeste indicando ausência de estruturação genética para esta espécie enquanto para A. fraterculus e A. sororcula foi encontrado uma sub estruturação que separa A. sororcula do Nordeste e A. sororcula do Sudeste, sendo que A. sororcula do nordeste pode estar hibridizando com A. fraterculus do Nordeste. As análises de migração encontraram migrações diferenciais para estas espécies, colocando A. obliqua mais isolada das demais e uma relação mais próxima entre A. fraterculus e A. sororcula. De frente aos resultados encontrados neste trabalho fica claro a necessidade de uma maior amostragem, principalmente em áreas ainda não coletadas entre as regiões amostradas na tentativa de buscar entender não apenas quais são as possíveis relações entre A. fraterculus e A. sororcula mas também entre outras espécies do grupo fraterculus.

De nombreuses invasions par les mouches des fruits de la famille des Tephritidae sont observées dans le monde. C'est notamment le cas aux Comores, de par sa position géographique et de ses importations de produits frais depuis les pays voisins. Afin de déterminer les stratégies nécessaires permettant de diminuer les populations de plusieurs espèces de cette famille, il est indispensable de disposer d'un état des lieux sur l'écologie et la distribution des espèces présentes dans l'archipel. Les objectifs de cette thèse étaient : i) d'inventorier les espèces de Tephritidae présentes aux Comores et d'analyser les fluctuations saisonnières des populations en lien avec les facteurs climatiques et la phénologie des principales plantes-hôtes, ii) de déterminer la gamme de plantes-hôtes des principales espèces et iii) d'inventorier les parasitoïdes indigènes des Tephritidae et de suivre l'acclimatation du parasitoïde Fopius arisanus introduit à partir de 2013. Afin de mener à bien ces objectifs, un suivi hebdomadaire d'un réseau de piégeage ainsi que la phénologie des plantes présentes dans les îles Grande-Comore, Mohéli et Anjouan, a été réalisé durant une période deux ans. De même, des fruits cultivés et sauvages ont été échantillonnés dans différentes régions de la diversité écoclimatique de l'île de la Grande-Comore durant une période de trois ans. Cinq espèces de mouches de fruits ont été retrouvées dans l'ensemble de l'archipel à partir du réseau de piégeage : Bactrocera dorsalis, Ceratitis capitata, Dacus bivittatus, Dacuspunctatifrons et Dacus ciliatus. Une forte dominance de l'espèce envahissante B. dorsalis a été observée à toutes les saisons et dans tous les sites. La densité des espèces de Tephritidae était plus importante durant la saison chaude et humide que pendant la saison fraiche et sèche. De plus, les résultats ont montré une forte abondance de B. dorsalis dans les régions humides de basses altitudes alors que C. capitata, subsiste dans les régions sèches et d'altitude plus élevée. Les résultats suggèrent un phénomène de séparation de niches entre ces deux espèces liée au climat. Parmi 42 espèces de fruits échantillonnées apparentant à 22 familles de plantes, 22 fruits de 11 familles étaient infestés par des Tephritidae. Six espèces de mouches des fruits ont émergées des fruits échantillonnés avec une large dominance (91%) de B. dorsalis. Cette dernière espèce occupe une large gamme de plantes-hôtes (16 espèces), utilisant des fruits préalablement infestés par C. capitata. Quatre espèces de parasitoïdes de la famille des Braconidae, sous-famille d'Opiinae ont émergés des fruits dont l'espèce introduite F. arisanus. Cependant très peu d'individus ont été retrouvés pour le moment et il sera nécessaire de suivre l'acclimatation du parasitoïde, en termes de taux de parasitisme, de distribution et de gamme de fruit et d'espèces de Tephritidae hôtes. / Numerous invasions by fruit flies of the Tephritidae family are observed worldwide. This is particularly the case in Comoros, because of its geographical position and its imports of fresh products from neighboring countries. In order to determine the strategies necessary to reduce the populations of several species of this family, it is essential to have a current status on the ecology and distribution of the species present in the archipelago. The objectives of this thesis were to: (i) inventory the Tephritidae species present in Comoros and analyze the seasonal fluctuations of populations in relation to climatic factors and phenology of the main host plants, (ii) determine the host plants range of the main species and (iii) inventory the Tephritidae indigenous parasitoids and follow the acclimatization of theparasitoid Fopius arisanus introduced since 2013. In order to achieve these objectives, a weekly monitoring of a trapping network as well as plants phenology present in Grande-Comore, Mohéli and Anjouan islands was carried out during a period of two years. Similarly,cultivated and wild fruits were sampled in different regions of the ecoclimatic diversity of Grande-Comore island during a period of three years. Five fruit fly species were found throughout the archipelago from the trapping network: Bactrocera dorsalis, Ceratitis capitata, Dacus bivittatus, Dacus punctatifrons and Dacus ciliatus. High dominance of the invasive species B. dorsalis was observed at all seasons and at all sites. The density of Tephritidae species was greater during the hot and wet season than during the cool and dry season. In addition, the results showed a high abundance of B. dorsalis in humid regions of low altitudes while C. capitata, persists in dry regions of higher elevation. The results suggest a niche separation phenomenon between these two species related to climate. Among 42 fruit species sampled from 22 plant families, 22 fruits belonging to 11 families were infested with Tephritidae. Six fruit fly species have emerged with a large dominance (91%) of B. dorsalis. The latter species occupies a wide range of host plants (16 species), using fruits previously infested with C. capitata. Four parasitoids species of Braconidae subfamily Opiinae have emerged in fruits including introduced species F. arisanus. However, very few individuals have been found at this timeand it will be necessary to follow acclimatization of the parasitoid in terms of parasitism rates, distribution and host fruit and Tephritidae species range.

Made available in DSpace on 2016-02-26T14:53:12Z (GMT). No. of bitstreams: 1 VeruskaLopesPereira.pdf: 546230 bytes, checksum: eaf7a47cfff5e212575e2312e3793c86 (MD5) Previous issue date: 2008-03-19 / Populational patterns of frugivorous flies (Diptera: Tephritoidea) in a fragment of Semidecidual Forest and in an orchard in the Region of Dourados, MS, Brazil. The Fruit flies are important pests in the word wide horticulture. These pests cause significant losses in the production of fruits and are responsible for the limitation in the free traffic of fruits, because their presence induce quarantine restrictions by importer countries of fruit and vegetables. The extension of loses are directelly related to the abundance of frugivorous fly populations. By other hand, the populations of Tephritoids are influenced by the abiotic (temperature, relative air humidity and rainfall) and biotic factors (host fruit availably and natural enemies action). This survey was carried out in a fragment semidecidual forest (22º12 S e 54º55 W) and in a commercial mixed orchard (22º 13 S 54º 43 W). The aim of this paper is: 1) to compare the abundance and the species richness of fruit flies caught in McPhail traps instaled in the edge and in the middle of the native forest, in the edge and middle of the commercial orchard; 2) survey the population fluctuation of the most abundant species of fruit fly in both ecosystems, loocking for some relationship with the abiotic factors and with plant phenology. C. capitata was the most abundant species, representing more than 80% of the caught adults of fruit flies. From Anastrepha spp. were identified 292 females, belonging to 12 species, being A. sororcula the most abundant fly (50,68%). C. capitata and A. sororcula were dominant. There were no significant differences in the abundance of frugivorous flies caught in the edge or in the middle of the forest neither in the edge and middle of the commercial orchard. Although, there are significant difference in the species diversity. The traps installed in the edge of the forest shows higher diversity index (H = 2.12). By other hand, the traps installed in the middle of commercial orchard captured higher species richness but with lower diversity index ((H = 0.408). The climatic factors were not the only ones that interfered in the population fluctuation of Anastrepha spp. and C. capitata in the surveyed environments. There was no correlation among the population fluctuation of the Anastrepha species with and the phenological stages of the fruit trees. But C. capitata populations were positively correlated with the stages of flowering, green fruits, ripe fruits and vegetative stages. The results in this paper corroborate with the prediction that in the ecotone there are higher species richness and diversity that in the middle of each one of the confronting ecosystems / Padrões Populacionais de Moscas Frugívoras (Diptera: Tephritoidea) em um Fragmento de Floresta Semidecidua e em um pomar Comercial da Região de Dourados, MS, Brasil. As moscas-das-frutas são consideradas importantes pragas da fruticultura mundial. Causam perdas significativas à produção e limitam o livre transporte de frutas devido às restrições quarentenárias impostas pelos países importadores. A extensão dos prejuízos tem relação direta com a abundância dos tefritídeos, que, por sua vez, pode ser influenciada por fatores abióticos (temperatura, umidade relativa do ar, do solo e precipitação pluviométrica) e bióticos (disponibilidade de hospedeiros e ação de inimigos naturais). O conhecimento da flutuação populacional de moscas-das-frutas é um requisito indispensável para o estabelecimento de um controle eficiente, pois permite viabilizar o planejamento de estratégias de manejo mais eficazes. A pesquisa foi conduzida em uma mata (22º12 S e 54º55 W) e um pomar comercial (22º 13 S 54º 43 W). Os objetivos deste trabalho foram: 1) comparar a abundância e a composição de espécies de moscas-das-frutas capturadas em armadilhas McPhail instaladas na margem e no interior de uma mata, na margem e no interior de um pomar comercial, e 2) avaliar a flutuação populacional das espécies de moscas-das-frutas mais abundantes nos ecossistemas e relacioná-las com fatores abióticos e bióticos. C. capitata foi à espécie mais abundante representando 80% dos adultos capturados. De Anastrepha foram identificadas 292 fêmeas pertencentes a 12 espécies, sendo A. sororcula a mais abundante (50,68%). C. capitata e A. sororcula foram dominantes. Não houve diferença significativa na abundância de moscas frugívoras capturadas na margem e no interior da mata, nem na margem e interior do pomar comercial. No entanto, houve diferença significativa na diversidade de espécies, as armadilhas instaladas na margem da mata apresentaram maiores índice de diversidade (H = 2,12). Por outro lado, as armadilhas instaladas no interior do pomar comercial capturaram maior número de espécies, embora com índice (H = 0,408) menor. Os fatores climáticos não foram os únicos determinantes da flutuação populacional de Anastrepha e C. capitata nas áreas estudadas. Não houve correlação entre a flutuação populacional das espécies de Anastrepha com os estágios fenológicos das plantas. No entanto, C. capitata apresentou correlação positiva com os estágios de floração, frutos verdes, frutos maduros e com os estágios vegetativos. Os resultados deste trabalho corroboram com a premissa de que, no ecótone, há uma maior riqueza e diversidade de espécie que no centro de cada um dos ecossistemas confrontantes

La lutte biologique à l’aide de champignons entomopathogènes est une des alternatives aux insecticides de synthèse. La thèse étudie la spécificité, la persistance et la dispersion de souches du genre Beauveria ainsi que le potentiel d’une stratégie d’utilisation innovante. À l’aide de tests de pathogénicité, un premier volet décrit le spectre d’hôtes physiologique de trois souches commerciales de B. bassiana et B. hoplocheli. Ces travaux révèlent des différences significatives entre souches. Néanmoins, elles possèdent toutes un large spectre d’hôtes, qui permet notamment d’envisager une extension d’usage pour lutter contre les mouches des fruits. Le second volet explore le potentiel d’une stratégie de lutte biologique ciblant spécifiquement les femelles de la mouche du melon, basée sur l’auto-dissémination de champignons entomopathogènes en utilisant les mâles comme vecteurs de spores. À l’aide d’un dispositif expérimental original, nous démontrons que la transmission de spores des mâles aux femelles lors de l’accouplement augmente significativement la mortalité des femelles. À la Réunion, depuis 30 ans, un programme de lutte contre un ver blanc de la canne à sucre est basé sur l’utilisation de B. hoplocheli. Le troisième volet étudie, à l’aide de marqueurs microsatellites, la diversité génétique de B. hoplocheli dans un réseau de parcelles de canne à sucre sur trois ans. La diversité génétique se relève très faible et nous identifions des génotypes de souches introduites dans les années 1980. Ces résultats suggèrent que les souches introduites au début de la lutte se sont maintenues et répandues dans l’agro-système réunionnais. / Biological control using entomopathogenic fungi is one of the alternatives to chemical insecticides. The thesis studies the specificity, persistence and dispersion of Beauveria strains and the potential of an innovative use strategy. Using pathogenicity tests, a first chapter describes the host range of three commercial strains of B. bassiana and B. hoplocheli. These studies reveal significant differences between strains. Nevertheless, they all have a broad host range, which allows considering extending their use against fruit flies. The second chapter explores the potential of a biocontrol strategy specifically targeting females of the melon fruit fly, based on the auto-dissemination of entomopathogenic fungi using males as spore vectors. Using an original experimental design, we demonstrate that spore transmission from male to female during mating significantly increases female mortality. In Reunion, for 30 years, a biocontrol program for a sugarcane white grub has been based on the use of B. hoplocheli. The third chapter investigates the genetic diversity of B. hoplocheli strains using microsatellite markers in a three years survey in sugarcane fields. We reveal a very low genetic diversity and identify genotypes of strains introduced in the 1980s. These results suggest that the strains introduced at the beginning of the biological control persisted and spread in the Reunion agro-ecosystem.