Submitted by (edna.saturno@ufrpe.br) on 2016-12-02T11:27:57Z No. of bitstreams: 1 Marcos Aurelio Paes de Oliveira.pdf: 851630 bytes, checksum: 2143362518b27ef1e6da1fcf00bdbee8 (MD5) / Made available in DSpace on 2016-12-02T11:27:57Z (GMT). No. of bitstreams: 1 Marcos Aurelio Paes de Oliveira.pdf: 851630 bytes, checksum: 2143362518b27ef1e6da1fcf00bdbee8 (MD5) Previous issue date: 2011-02-07 / Atlantic forest fragments, surrounded by crops such as sugarcane, may undergo changes in terms of termite community richness and composition. This study aimed to analyze termite richness in Pernambuco's sugarcane region and to compare the communities found in sugarcane plantations and in Atlantic forest fragments near such plantations. For the richness study, four 1 ha areas were delimited within the plantations in each sugarcane processing plant selected – Trapiche, União & Indústria, São José, and Central Olho D'Água. A comparative analysis between the termites that occur in forest fragments and in sugarcane plantations was carried out at the São José processing plant, where three transects were placed 10, 50, and 300 m parallel to each environment's border, respectively. The insects were collected from all of the micro-habitats in ten intercalated sectors of 10 m2 for each transect. The richness study in the sugarcane plantations recorded 13 species of eight genera and two families (Rhinotermitidae and Termitidae). The number of species varied from six to nine per processing plant. Twelve Termitidae species occurred, of which Subfamily Nasutitermitinae was the richest (S=6). Rhinotermitidae included only one species, which belonged to Subfamily Heterotermitinae. The comparative analysis between the two environments studied revealed 27 termite species in the Atlantic forest fragments, from 17 genera and three families. Termitidae had the greatest number of species (24), Subfamily Nasutitermitinae was the richest. Ten species occurred in sugarcane, including six genera and one family; Subfamily Syntermitinae stood out in terms of species number (S=4). The results showed a higher termite richness than what had been previously recorded for Pernambuco's sugarcane plantations. Additionally, termite associations to forest fragments and sugarcane plantations were distinct – for the latter, species richness decreased the further away the transects were from the forest's edge. / Fragmentos florestais de Mata Atlântica, circundados por culturas como a cana-de-açúcar, podem sofrer alterações na riqueza e na composição de comunidades termíticas. O objetivo deste trabalho foi analisar a riqueza de cupins nas regiões canavieiras de Pernambuco e comparar as comunidades termíticas existentes em cana-de-açúcar e remanescentes de Mata Atlântica, próximas a canaviais. No estudo da riqueza delimitaram-se quatro áreas de um hectare para cada Usina – Trapiche, União & Indústria, São José e Central Olho D`água. A análise comparativa entre os cupins que ocorrem em fragmentos de mata e em canavial foi realizada na Usina São José, onde foram traçados três transectos a 10, 50 e 300 metros, respectivamente, paralelos à borda de cada ambiente. Em 10 setores intercalados, de 10m2, de cada transecto, os insetos foram coletados em todos os micro-habitats. O estudo de riqueza nos canaviais registrou 13 espécies pertencentes a oito gêneros e a duas famílias (Rhinotermitidae e Termitidae). O número de espécies variou de seis a nove por Usina. Em Termitidae ocorreram 12 espécies, com a subfamília Nasutitermitinae apresentando maior riqueza (S=6). Rhinotermitidae contou com apenas uma espécie da subfamília Heterotermitinae. A análise comparativa entre os dois ambientes estudados registrou 27 espécies de cupins nos fragmentos de Mata Atlântica, sendo 17 gêneros e três famílias. Termitidae apresentou maior número de espécies (24) e a maior riqueza (S=12) foi observada na subfamília Nasutitermitinae. Em cana-de-açúcar ocorreram 10 espécies incluídas em seis gêneros e em uma família, tendo a subfamília Syntermitinae se destacado em número de espécie (S=4). Os resultados apresentaram uma riqueza de térmitas mais elevada que aquela previamente registrada para os canaviais pernambucanos e a associação termítica entre os fragmentos de mata e cana apresentaram-se distintas, havendo diminuição na riqueza de espécies, nessa última, à medida que os transectos se afastavam da borda da mata.

The presence of soldier caste is an important synapomorphy of group Isoptera. The adaptation of this caste to defense tasks is more than obvious and some of their morphological or even behavioral adaptations can be quite impressive. The polyethism in termites is relatively well known inbetween rather worker caste. If there are such a studies pointing at polyethism in soldiers, they are connected with soldier polymorphism. The morphological differences are of course important stimulus to role separation. The goal of this thesis was to examine the polyethism in the species of the termite with monomorphic soldiers - Prorhinotermes simplex. I did behavioral experiments with it in enclosed arenas, recorded on specific days. The data shows, that there are differences inbetween individuals and it would be benefical to invest further time to subsequent studies. The thesis bring out new point of view to defensive behaviour of termites and suggests, that even termite species without polymorphic species may have soldiers with different tasks. Besides I managed to map ontogeny of soldier behaviour in the first two weeks after moulting from presoldier instar. Key words: Isoptera, polyethism, soldiers, ontogeny, defensive behaviour Powered by TCPDF (www.tcpdf.org)

This thesis reports on the number of individuals in Macrotermes natalensis (Hav.) colonies, their biomass and food consumption in the northern Kruger National Park (KNP). The ecology of M. natalensis is largely undocumented despite the abundance of colonies in southern African savannas. New approaches to mound excavation, sub-sampling and data management are introduced. Via the intracolonial demography of colonies the contribution of each caste in number or proportion is determined. Using this information in combination with body mass and mound density data, biomass per unit area has been computed indicating the importance of this termite in synecology. The measurement of food consumption gives further insight as to how much litter is removed, fragmented and redistributed as nutrients in the ecosystem. Mounds were completely excavated, termites collected by means of vacuuming, and colony size estimated by sub-sampling. It was estimated that, on average, small mounds contain more than 5 000, medium mounds more than 45 000, and large mounds more than 200 000 individual termites. A highly significant relationship between total number of individuals (N ) and mound height (h ) was found, given by lnN = 7.893 + 1.093h (r = 0.92). The proportion of soldiers was found to change as colonies grew larger. In order to derive biomass estimates, a statistical bootstrap procedure was carried out using three databases: body mass, colony population sizes and mound density. Live biomass for small, medium and large mounds was found to be 0.17, 1.40 and 4.16 kg. Dry/wet body mass ratios were established for workers (23.7 %), major soldiers (20.3 %), minor soldiers (35.3 %), nymphs (17.1 %), king (35.4 %) and queen (20.8 %). Average live and dry biomass was calculated to be 0.51 kg/ha (0.051 g/m2) and 0.11 kg/ha (0.011 g/m2). Geology, geomorphology, elevation, local relief, soil patterns and annual rainfall were the abiotic factors shown to be most influential in determining termite biomass, either directly or indirectly. Termite biomass is high in undulating areas where the elevation is 250-400 m, where granitic and rhyolitic soils occur, and where annual rainfall is high (650-700 mm) in the context of the region. Major workers fetch woody litter outside the nest through ingestion into the section of the crop and gizzard. Gut contents were dried, weighed, ashed and reweighed. The ash mainly represents soil particles. The ash-free mass of food that is consumed during a single foraging trip by a foraging individual is 0.166 ± 0.009 mg (CI). Frequency of foraging trips between the mound and food source was observed using translucent tubing. The annual food consumption is given by the formula 365mnp/t , where m = individual mass of ashed crop-gizzard contents, n = number of foraging major workers, p = daily foraging period, and t = individual time spent between nest and food source. Food consumption of this termite in the northern KNP is calculated to be 20.2 kg/ha/yr. It is shown that termites are primary decomposers and contribute to litter fragmentation and the recycling of nutrients into the soil. This thesis gives greater insight into aspects such as colony development, biomass investment and resource utilization of M. natalensis in the northern KNP. / Dissertation (PhD)--University of Pretoria, 2003. / Zoology and Entomology / unrestricted

Polyneoptera is an assemblage of eleven insect orders comprising the "orthopteroid" insects. It includes familiar insects such as grasshoppers, roaches, termites, earwigs and preying mantises; as well as the more obscure web-spinners, angel insects and ice-crawlers. We present a phylogenetic analysis of the polyneopteran orders based on 18S rDNA, 28S rDNA, Histone 3, and a coded morphology matrix for an extensive sampling of taxa. We investigate the use of congruence between separate datasets as an a priori measure of alignment quality. Our results support the paraphyly of Polyneoptera, the monophyly of Dictyoptera, sister taxon relationships between Embiidina + Phasmatodea and Dermaptera + Zoraptera, and a relatively basal placement of Plecoptera. The analyses also support a sister taxon relationship between the newly described Mantophasmatodea and Grylloblattodea, a small order of cryophilic insects confined to the northwestern Americas and northeastern Asia. This placement coupled with the morphological disparity of the two groups validates the creation of a new order for Mantophasmatodea. Our results also suggest the Direct Optimization (formerly Optimization Alignment) produces alignments that are more predictable across the parameter landscape than alignment via CLUSTAL X, as measured by congruence among independent data partitions. Dense taxon sampling and phylogenetic analysis of six molecular markers (12S, 16S, 18S, 28S, COII, and H3) and morphological data for the order Plecoptera demonstrates that the subordinal groups Arctoperlaria and Antarctoperlaria are monophyletic. Euholognatha and Systellognatha are also monophyletic, with the exception of the genus Megaleuctra which is the basal lineage for the order and deserves recognition as a distinct family (Megaleuctridae). Notonemouridae is strongly supported as a monophyletic clade. Within the Systellognatha Styloperlidae is the basal lineage, followed by Peltoperlidae then Pteronarcyidae, and Perloidea is a strongly supported monophyletic group with Chloroperlidae as sister taxon to Perlidae + Perlodidae. The family Gripopterygidae is strongly supported as paraphyletic. Many Plecoptera (stoneflies) exhibit a pre-mating communication known as "drumming." Species of the genus Isogenoides have complex drumming behavior in which (i) the male calls the female by tapping his abdomen against the substrate, (ii) the female answers with her own distinctive tapping, and (iii) the male responds with a confirmatory series of taps. These drumming patterns are specific to individual species and may vary within a species to form distinct dialects. Phylogenetic analysis for the genus based on six molecular markers (12S, 16S, 18S, 28S, COII, and H3) supports Yugus as its nearest extant relative and I. hansoni as the basal lineage within the genus. Drumming behavioral characters appear to be largely incongruent with the phylogeny.

The traditional view of a lifelong monogamy between a king and a queen has recently been challenged in termites. In several species, multiple parthenogenetically-produced secondary queens replace the primary queen and mate with the primary king; this strategy is referred to as “Asexual Queen Succession” (AQS). The aim of my thesis was to investigate the modalities of reproduction and the ecology of neotropical soil-feeding termites from the Termitinae, with a focus on the inquiline termite Cavitermes tuberosus in the Termes group.In the first axis, we investigated the modalities of reproduction of C. tuberosus. (i) AQS is the main reproductive strategy of this species. (ii) The evolution of AQS requires the propensity of parthenogens to develop into neotenic queens. In C. tuberosus, secondary queens develop from a developmental stage of “aspirants” which participate to the social tasks usually undertaken by workers, as long as the primary queen is alive. (iii) In AQS species, a female-biased sex ratio is expected in the dispersing reproductives. In C. tuberosus, sex ratio varies among years and according to the type of reproductives, and the population sex ratio is balanced. These results raise hints on queen-king conflict over the sex ratio.In the second axis, we described the ecology and symbioses of C. tuberosus. (iv) Wolbachia, an endosymbiotic bacterium mainly known for manipulating the reproduction of arthropods in order to enhance its own transmission, infects all individuals in societies. This bacterium, particularly abundant in a gut-associated bacteriome, may play a role in the nutrition of C. tuberosus; both partners would have evolved a mutualistic symbiosis. (v) Inquiline termites live in a nest built by other termite species and do not forage outside. Physico-chemical measures and microbiota sequencing revealed that C. tuberosus is a generalist nest-feeder.Finally, we expanded our study of the breeding systems in the phylogenetic proximity of C. tuberosus. (vi) We described Palmitermes impostor, a new genus and species as a sister-group to the genus Cavitermes. (vii) AQS is the main reproductive strategy in P. impostor, and queens of Spinitermes trispinosus and Inquilinitermes inquilinus are able to reproduce parthenogenetically. Therefore, it appears likely that the conditional use of sexual and asexual reproductions is a preadaptation common to the whole Termes group, and that it evolved into a stable element of their breeding system at least in some species.Overall, our results open new perspectives in the understanding of reproductive strategies in termites and their relationships with their bacterial symbionts. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / A range of behavioral strategies and sensory abilities allow animals to minimize costs involved in the search for food. Among the factors involved in the variation of foraging costs, the availability of resources represents a central role and it is recognized for modulating the animal home range. Some species of termites can exhibit characteristics that make the foraging process even more expensive. Species belonging to the genus Nasutitermes, for example, have an extra cost in foraging: in addition to build a network of tunnels to access resources, they have a large number of soldiers, a caste trophically dependent. In the present study: (i) we evaluated the foraging pattern in Nasutitermes aff. coxipoensis (Termitidae: Nasutitermitinae), including the searching strategy and the role of soldiers; and (ii) we analyzed whether colonies of this species responds to variations in the availability of food resources. Manipulative experiments were conducted in the field and in the laboratory to analyze the pattern of foraging in N. aff. coxipoensis. For this, 35 nests were transplanted into areas of dunes in Pirambu-SE. Seven plots were established in a continuous increament in the density of resources (sugarcane baits). Laboratory tests were conducted to examine the role of chemical signals (eg. trail pheromone) present in the sternal gland of workers and soldiers. During 10 consecutive days it was measured: the number of trails and tunnels, their total length, number of branches and the tunneling speed (cm/day). Data were analyzed using generalized linear models and mixed linear models. Nasutitermes aff. coxipoensis showed mainly nocturnal foraging. Soldiers were the first individuals to start the foraging, however, in established trails, the number of workers were always higher than soldiers. The number of active trails remained constant over the observation period, while the number of tunnels increased. In groups of soldiers and workers, the workers chose to follow the trail signals of soldiers. The number of trails, the total length and their branches decreased with increment of resource availability. The conversion of trails in tunnels increased in areas with higher resource density. Our results suggest that the costs involved in the production of soldiers in N. aff. coxipoensis seem to be compensated by their decisive role during the foraging process. Colonies of this species seem to optimize their foraging through a combined strategy of constructing trails and tunnels. In places with low resource availability, termites forage mainly on trails, avoiding to convert trails in tunnels. This strategy has not yet been reported in the literature. Thus, N. aff. coxipoensis presents strategies in order to optimize the foraging, minimizing costs involved in this process. These results can contribute to the key question about the evolution of termite foraging behavior, as well as to understand the mechanisms involved in the distribution patterns and structuring communities of these insects. / Uma gama de estratégias comportamentais e habilidades sensoriais permite aos animais minimizar os custos envolvidos na busca por alimento. Dentre os fatores envolvidos na variação dos custos de forrageio, a disponibilidade de recursos representa um papel central e é reconhecida por modular as áreas de uso dos animais. Algumas espécies de cupins exibem características que podem tornar o processo de forrageio ainda mais oneroso. Espécies do gênero Nasutitermes, por exemplo, apresentam gastos extras no forrageio, uma vez que além de construírem uma rede de túneis para acessar os recursos, ainda apresentam um elevado número de soldados, indivíduos troficamente dependentes. No presente estudo, avaliamos (i) o padrão de forrageio em Nasutitermes aff. coxipoensis (Termitidae: Nasutitermitinae), incluindo as estratégias de busca e o papel dos soldados; e (ii) analisamos se colônias desta espécie respondem à variação na disponibilidade de recursos. Experimentos manipulativos foram conduzidos em campo e em laboratório a fim de analisar o padrão de forrageio de N. aff. coxipoensis. Para isso, 35 ninhos foram transplantados em áreas de dunas, em Pirambu- SE. Foram estabelecidas sete parcelas em um contínuo de aumento da densidade de recursos (iscas de cana-de-açúcar). Testes em laboratório foram realizados a fim de analisar o papel dos sinais químicos (ex. feromônio de trilha) presente na glândula esternal de operários e soldados. Durante 10 dias consecutivos foram quantificados: o número de trilhas e de túneis, o comprimento total, o número de ramificações destes e a velocidade de construção dos túneis. Os dados foram analisados utilizando-se modelos lineares generalizados e modelos mistos. Nasutitermes aff. coxipoensis apresentou forrageio principalmente noturno. Soldados foram os primeiros indivíduos a iniciarem o forrageio, no entanto, em trilhas já estabelecidas, o número de operários foi sempre maior do que o de soldados. O número de trilhas ativas permaneceu constante ao longo do período de observação, enquanto o número de túneis aumentou de forma gradativa. Em grupos compostos por soldados e operários, os operários preferiram seguir os sinais de trilha dos soldados. O número de trilhas, o comprimento total e suas ramificações reduziram com o aumento da disponibilidade de recursos. A conversão de trilhas em túneis aumentou em locais com maior densidade de recursos. Nossos resultados sugerem que os custos envolvidos na produção de soldados de Nasutitermes aff. coxipoensis parecem ser compensados pelo seu papel decisivo no forrageio. Colônias desta espécie parecem otimizar o forrageio através de uma estratégia combinada de formação de trilhas e túneis. Em locais com baixa disponibilidade de recursos os cupins forrageiam preferencialmente em trilhas, evitando a conversão destas em túneis. Tal estratégia, ainda não foi relatada na literatura. Assim, N. aff. coxipoensis apresenta estratégias para otimização do forrageio, minimizando os custos envolvidos nesse processo. Os resultados deste estudo podem contribuir para a investigação de questões sobre evolução do comportamento de forrageio de cupins, assim como para desvendar os mecanismos envolvidos nos padrões de distribuição e estruturação de comunidades desses insetos.

Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Termites display a key role in the terrestrial ecological ecosystems by positively contributing to maintenance of these ecosystems. However, despite this importance, some species are known as urban, forests, and agriculture pests. At urban areas, Cryptotermes brevis (Kalotermitidae) and Nasutitermes corniger (Termitidae: Nasutitermitinae) species are because of its attack to structure and wood pieces, causing a high damage to those materials. The use of conventional insecticide is the main control method for these pests. However, the adverse effects in the use of these products, and the demand for others with lower toxicological risks have been motivating the realization of research with natural products. Thus, in this study, we evaluate the lethal, and sub lethal effects of Aristolochia trilobata (Aristolochiaceae) and Lippia sidoides (Verbenaceae) essential oils, and their major compounds under N. corniger and C. brevis, respectively. The essential oils and its compounds were toxic to N. corniger and C. brevis. These treatments reduced the behaviour and walking of termites, as well showed repellent effect. From these results, we have strongly evidences that A. trilobata and L. sidoides, as well as their constituints could be used in control strategies, on a substitute and/or complimentary way, of N. corniger and C. brevis. / Os cupins desempenham importantes papéis ecológicos nos ecossistemas terrestres contribuindo positivamente para a manutenção desses sistemas naturais. Porém, apesar desta importância, algumas espécies são consideradas pragas em ambientes urbanos e em cultivos agrícolas e florestais. Nas áreas urbanas, as espécies Cryptotermes brevis (Kalotermitidae) e Nasutitermes corniger (Termitidae) são destaque pelo seu ataque a estruturas e peças de madeira, danificando estes materiais. O uso de inseticidas convencionais é o principal método de controle destas pragas. Porém, os efeitos adversos da utilização destes produtos e a demanda por outros com menor risco toxicológico tem motivado a realização de pesquisas com produtos naturais. Assim, neste trabalho, avaliamos os efeitos letais e subletais dos óleos essenciais de Aristolochia trilobata (Aristolochiaceae) e Lippia sidoides (Verbenaceae), e seus constituintes majoritários sobre N. corniger e C. brevis, respectivamente. Os óleos essenciais e seus constituintes foram tóxicos a N. corniger e C. brevis. Estes tratamentos alteraram os comportamentos e o caminhamento dos cupins, além de apresentar efeito repelente. A partir destes resultados temos fortes evidências que os óleos essenciais de A. trilobata e L. sidoides, e seus constituintes majoritários poderão ser utilizados em estratégias de controle de forma substitutiva e/ou complementar de N. corniger e C. brevis.

With its unique consortium of microorganisms from all domains of life, termite gut is considered one of the most efficient lignocellulose degrading systems in nature. Recently, host diet and taxonomy as well as gut microenvironmental conditions have emerged as main factors shaping microbial communities in termite guts. The aim of this thesis was to investigate this highly efficient lignocellulolytic system at holobiont level, with a particular focus on gut microbiome function and composition in relation to the host diet. As a starting point, we optimised a complete framework for an accurate termite gut prokaryote-oriented metatranscriptomics, which was at the basis of all subsequent sequencing assay designs and analyses performed in the course of the work. Afterwards, we characterised the compositions and functions of biomass-degrading bacterial communities in guts of plant fibre- and soil-feeding higher termites, proving the existence of functional equivalence across microbial populations from different termite hosts. We also showed that each termite is a reservoir of unique microorganisms and their accompanying genes. We further extended above approach to metagenomics and bacterial genomes reconstruction and we applied it to explore the process of biomass digestion in the different sections of the highly compartmented gut of soil feeding Labiotermes labralis. We showed that primarily cellulolytic activity of the termite host was restricted to foregut and midgut, while bacterial contribution was most pronounced in P1 and P3 hindgut compartments and included activities targeting broad range of lignocellulose components. Finally, we investigated the adaptation of a laboratory-maintained grass-feeding higher termite colony of Cortaritermes spp. to Miscanthus diet at host and symbiont levels. A natural system of a termite gut was shown to progressively change in composition to yield a consortium of microbes specialised in degradation of a specific biomass. Overall, the integrative omics approach proposed here provide a framework for a better understanding of a complex lignocellulose degradation by a higher termite gut system and pave a road towards its future bioprospecting. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Soils represent an essential habitat for a wide diversity of invertebrates. Among these organisms, termites are considered ecosystem engineers for their impact on nutrient cycling and soil functioning, stemming from their wide feeding habits. For instance, soil/litter-feeding termites are one of the groups that incorporate the most organic matter from the soil. Thus, the high abundance and diversity of this group of termites does not only indicate its ecological success, but also its high value for the ecosystem. TheApicotermitinae subfamily (family Termitidae) is a highly diverse group of soil-feeding termites widespread in Afro- and Neotropical regions. However, due to taxonomic difficulties in soldierless groups and poor sampling of species living deep in the soil, it is also one of the most understudied subfamilies. In this thesis, I addressed phylogenetic, anatomical, and ecological aspects of the Apicotermitinae, with the ultimate goal of explaining their high diversity and ecological success. In the first axis, we investigated the phylogenetic relationships of Apicotermitinae species by using de novo mitochondrial genomes. African taxa with soldiers form several basal branches. We confirmed the monophyly of Asian and neotropical lineages, resulting from two independent dispersal events from tropical Africa, and established the relationships of the main lineages in the subfamily. The relationships among and within some genera remain unresolved, probably revealing an explosive radiation. Some genera appear as polyphyletic, showing the need for further taxonomic revision. In the second axis, we described for the first time in detail the anatomical structures of the gizzard. Thepulvillar belt bears a highly diverse, sclerotized and autofluorescent structures. These structures and the ornamentation patterns remain limited to African species since the Neotropical species do not present such specialized structures. Consequently, these ornamentations are proposed as a new complementary taxonomic tool, which can prove useful in the future revisions of genera with phylogenetic incongruences. In the third axis, we characterized the content of crop-gizzard and inferred the isotopic niche of species. Slight variations in the food content suggested that Apicotermitinae can be considered as a single feeding group, with mineralized soil as a primary source. Variations in the crop-gizzard volume can be related to food-collecting behavior. The neotropical species exhibited the broadest isotopic spaces, indicating flexibility to explore large organic matter humification gradients. The broad overlap of isotopic niches and co-occurrence with other termites suggests that this group could be affected by spatial segregation. Finally, in an evolutionary context, it was inferred that the Neotropical soldierless taxa underwent an explosive radiation during the early-middle Miocene. While the reduction of sclerotized structures in the gizzard is associated with the dispersal towards the Neotropics, the African soldierless species developed a pulvillar armature. All of these results provide an overview of the understanding of Apicotermitinae and open up new perspectives on the evolutionary and functional aspects of associations in favor of diet as an agent of their success. / Les sols représentent un habitat essentiel pour une grande diversité d'invertébrés. Parmi ceux-ci, les termitessont considérés comme des ingénieurs de l'écosystème, pour leur impact sur le cycle des nutriments ainsique sur le fonctionnement du sol. Ce rôle écologique majeur est du fait entre autres de la grande diversitéde leur régime alimentaire. Les termites qui se nourrissent de sol et/ou de litière constituent l'un des groupesqui incorpore le plus de matière organique depuis le sol. Ainsi, l'abondance et la diversité élevées de cegroupe de termites indiquent non seulement leur succès écologique, mais aussi leur forte valeur pour lesécosystèmes. La sous-famille des Apicotermitinae (Termitidae) constitue un groupe de termites humivorestrès abondant et diversifié dans les régions afrotropicale et néotropicale. Cette sous-famille est pourtant peuétudiée, du fait des difficultés taxonomiques rencontrées pour les termites sans soldats, mais aussi desdifficultés d’échantillonnage associées aux espèces propres aux sols plus profonds. Le présent travail dethèse se veut être une étude de la diversité des Apicotermitinae selon trois axes, à savoir phylogénétique,anatomique et écologique, dans le but d'expliquer les tenants et aboutissants de la grande diversité desApicotermitinae, ainsi que les raisons de leur succès écologique.Dans le premier axe de la thèse, nous avons étudié les relations phylogénétiques entres les différentesespèces d’Apicotermitinae à l’aide de génome mitochondriaux assemblé de novo. Les taxa africains avecsoldats forment plusieurs branches basales. Nous avons confirmé la monophylie des lignées asiatique etnéotropicale, qui résultent de deux colonisations indépendantes au départ de l'Afrique, et établi les relationsentre les principales lignées de la sous-famille. Les relations, entre ou au sein, de certains genres sont malrésolues et correspondraient à une explosion radiative. Plusieurs genres apparaissent commepolyphylétiques, montrant le besoin d’une révision taxonomique future.Dans la deuxième partie de la thèse, nous avons décrit pour la première fois en détail les différentesstructures anatomiques du gésier. La ceinture pulvillaire porte des structures très diverses, sclérifiées etauto-fluorescentes. Ces ornementations sont proposées comme un nouvel outil taxonomiquecomplémentaire, qui serait utile pour les révisions requises dans les genres problématiques susmentionnés.Ces structures et les motifs d'ornementation restent toutefois limités aux espèces africaines, les espècesnéotropicales ne présentant pas de structures spécialisées.Concernant le troisième axe de la thèse, nous avons caractérisé le contenu du jabot-gésier et estimé la nicheisotopique de différentes espèces. Les légères variations du contenu suggèrent que les Apicotermitinaepartagent sensiblement le même régime alimentaire, en ingérant une quantité importante de sol minéralisé.Les variations du volume du jabot-gésier peuvent être liées au comportement de collecte des aliments. Lesespèces néotropicales montrent une étendue des niches isotopiques plus large, ce qui indique la possibilitéd'exploiter plusieurs niveaux d’humification de la matière organique. Le large chevauchement des nichesisotopiques et la co-occurrence avec d'autres termites suggèrent que les espèces de ce groupe tendraient àse ségréger spatialement.Enfin, dans un contexte évolutif, il a été estimé que le groupe des espèces néotropicales sans soldats a subiune explosion radiative au début du Miocène moyen. Alors que la réduction des structures fortementsclérifiées dans le gésier est associée à la dispersion vers les Néo-tropiques, les espèces africaines sanssoldats ont développé une armature pulvillaire. L'ensemble de ces résultats donne un aperçu de lacompréhension des Apicotermitinae et ouvre de nouvelles perspectives quant à des aspects évolutifs etfonctionnels des associations en faveur du régime alimentaire en tant qu'agent de leur succès. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

- Extended longevity and high fecundity are two phenomena typical for reproductive castes (queens, eventually kings) of eusocial insects. In my thesis, we explore the hypothesis that the longevity of reproductives in the termite Prorhinotermes simplex is linked with the activation of the telomerase enzyme complex. Telomerase is well known for its life-extension functions, due especially to its capacity to prolong the telomeric ends of chromosomes. Therefore, we studied here the gene expression of: (1) the gene TERT coding for the catalytic subunit of the telomerase and (2) the genes of the main endocrine regulatory pathways, known to be responsible for the control of reproduction and longevity in insects. Expression dynamics of these genes were measured in sterile and reproductive castes of P. simplex during their development and sexual maturation. Based on our results obtained from the TERT expression analyses and their comparison with telomerase enzyme activities, we assume that the telomerase action in the long-lived reproductive individuals is regulated at a post-transcription level. Furthermore, we observed in reproductive castes a simultaneous upregulation of some transcription variants of vitellogenin and the genes for insulin signalling pathways. We can, therefore, conclude that in...