Les interactions « lichen-lichénophage » sont médiées par la présence de métabolites au sein des lichens qui peuvent influer sur les préférences alimentaires des lichénophages. Dans le contexte environnemental du Subantarctique, à faible biodiversité animale et « végétale », une étonnante richesse lichénique a contribué au succès de l’unique Gastéropode terrestre endémique, Notodiscus hookeri. Pour mieux comprendre les mécanismes en jeu, nous avons analysé les préférences alimentaires de cet escargot lichénophage et tenté de cibler les traits-clés des lichens qui modulent l’interaction trophique. À partir d’observations et de prélèvements réalisés sur l’île de la Possession (Archipel Crozet, Terres Australes et Antarctiques Françaises), deux étapes décisives de l’interaction ont été étudiées : (i) le comportement alimentaire de l’escargot en situation de choix nutritionnel, (ii) sa réponse gustative face à des métabolites en situation de non choix. Le broutage préférentiel de certaines parties de lichen a été confronté à l’analyse de la combinaison entre la teneur des métabolites secondaires et celle des métabolites primaires. La localisation des métabolites au sein du thalle de trois espèces lichéniques fréquentes sur l’île et consommées par l’escargot (Argopsis friesiana, Pseudocyphellaria crocata et Usnea taylorii) a été effectuée par l’intermédiaire de techniques chromatographiques et spectrométriques (LC-DAD-MS, GC-MS, microdissection couplée à la LC-DAD-MS, DART-MS) ainsi que par des techniques d’imagerie couplées à la spectrométrie de masse ((MA)LDI-MS). N. hookeri se révèle être une espèce généraliste et opportuniste qui se nourrit de la majorité des lichens auxquels il est confronté. Cependant, il opère des choix en se nourrissant des parties ayant une valeur nutritive élevée et ce, en dépit de la présence de métabolites secondaires potentiellement répulsifs. Plusieurs mécanismes permettant à l’escargot de contrer la toxicité de certains métabolites ont également été décrits dans ce travail. Les choix alimentaires de N. hookeri s’avèrent par conséquent répondre à un compromis entre le bénéfice d’absorption de métabolites appétents à forte valeur nutritive et le coût physiologique (détoxication, clivage, excrétion) engendré par l’ingestion de métabolites répulsifs. En conclusion, trois paramètres-clés au moins seraient à prendre en compte lors des futures études d’interactions entre lichens et lichénophages : il s’agit de la nature et de la teneur des métabolites secondaires, de la teneur en azote ainsi que de la quantité de sucres et de polyols. Les techniques d’imagerie ont fourni une voie nouvelle et prometteuse pour cibler les dégâts opérés par un phytophage. En effet, cette approche permet de mieux apprécier la distribution hétérogène au sein du thalle entre les métabolites. Pour cet escargot terrestre, les ratios de composés « appétents/inappétents » semblent jouer un rôle majeur dans la sélection de nourriture. / Lichen-lichenivore interactions are mediated by the presence of metabolites in lichens, which may impact lichenivore food preferences. In the environmental context of the Subantarctic, with a low animal and “plant” biodiversity, the surprising lichen flora contributed to the success of a the only endemic subantarctic land Gastropod, Notodiscus hookeri. To better understand the snail-lichen interactions, we analyzed the food preferences of this lichenivore snail and tried to pinpoint key lichen traits modulating the trophic interaction. From observations and samplings realized on Possession Island (Crozet Archipelago, Terres Australes et Antarctiques Françaises), two decisive stages of the interaction were studied: (i) the snail feeding behavior in situation of nutritional choice, (ii) its gustatory response when facing isolated metabolites in no-choice situations. Preferential grazing of some lichen parts was linked to both secondary and primary metabolites concentrations. Intrathalline localization of metabolites was performed in three lichen species consumed by the snail and widespread on Possession Island (Argopsis friesiana, Pseudocyphellaria crocata and Usnea taylorii), using chromatographic and spectrometric techniques (LC-DAD-MS, GC-MS, microdissection coupled to LC-DAD-MS, DART-MS) and imaging mass spectrometry ((MA)LDI-MS). N. hookeri appears to be a generalist and opportunistic gastropod, feeding on most lichen species encountered. However, it is able to discriminate between lichen parts, preferentially grazing on parts with the highest nutrient value, in spite of the presence of potential deterrent secondary metabolites. We described several mechanisms helping snails to overcome the toxicity of some lichen metabolites. Snail feeding choices result in trade-off between benefits of absorbing appetent metabolites of high nutritive value and the cost of physiological processes (detoxification, cleavage and excretion) caused by the ingestion of deterrent metabolites. To conclude, three main key parameters might be relevant in future to study the interactions between lichens and lichenivores. They correspond to the nature, the histolocalisation and the content of secondary metabolites balanced by the amount of nitrogen along with sugars and polyols. Imaging techniques have provided a new and promising way to visualize the heterogeneous distribution within the thallus between these metabolites. The ratios of appetent/non appetent compounds are likely to play a major role in food selection by this land snail.

Analytical chemistry plays a crucial role in studies on chemical ecology and only the development of sophisticated methods enables the detection of biologically active compounds that are usually present in minute quantities and often in very complex mixtures. My thesis is dedicated to the application of modern analytical techniques and instrumentation to unravel the identity, chemical diversity and function of semiochemicals and defensive compounds used by various species of termites. The first section of this thesis aims at the identity of chemicals used in communication, the pheromones. I studied the chemistry of the trail-following communication in three selected species of termites. Besides the identification of (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol, the most frequent termite trail-following pheromone, as the trail-following pheromone in Psammotermes hybostoma (Rhinotermitidae), I participated in the description of two new structures, (10Z,13Z)-nonadeca-10,13-dien-2-one in Glossotermes oculatus (Serritermitidae) and syn-4,6-dimethylundecan-1-ol in Hodotermopsis sjoestedti (Archotermopsidae). We identified (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol to be the female sex pheromone in Psammotermes hybostoma, and syn-4,6-dimethylundecanal to be the male sex pheromone in Hodotermopsis sjoestedti. I also...

[ES] La confusión sexual es el método de control de plagas basado en semioquímicos que ofrece los mejores resultados y tiene mayor aceptación en el mercado. Este método se basa en la liberación al ambiente de la feromona sexual del insecto al que se pretende controlar en una cantidad suficiente para provocar un retraso o una reducción del apareamiento. Los estudios dedicados a la optimización de la feromona utilizada, la cual condiciona en gran medida el precio del uso de esta técnica, se basan en ensayos empíricos sobre parámetros como el número de emisores utilizados y su distribución, la carga inicial de feromona, etc. La cuantificación de la concentración de feromona en aire es un parámetro más directo y ofrece información valiosa tanto para realizar estudios destinados a optimizar el uso de los emisores disponibles, como para el desarrollo de nuevos dispositivos de emisión con un menor uso de feromona. En la presente tesis se ha desarrollado una metodología que permite la cuantificación de la concentración de feromona en aire en condiciones reales de campo basada en la captación de volátiles del aire y su posterior análisis mediante técnicas de cromatografía de gases y espectrometría de masas. Mediante el uso de esta metodología se ha estudiado la cantidad de feromona en aire a lo largo del ciclo de cultivo en campos tratados con confusión sexual para dos especies diferentes de importancia agronómica en los cultivos de la viña y del arroz, la polilla del racimo de la vid (Lobesia botrana Denis & Schiffermüller) y el barrenador del arroz (Chilo suppressalis Walker) tratados con diferentes tipos de emisores. Estos estudios han servido para conocer de qué manera se distribuye la feromona en aire a lo largo del tiempo en relación con la cinética de los emisores y cuáles son los mecanismos implicados en la confusión sexual en condiciones reales. Además, también se ha estudiado la dependencia climática de emisores pasivos en condiciones de campo puesto que tendrá relación con la cantidad de feromona en aire y puede repercutir en la eficacia del método de control. Los resultados obtenidos en las parcelas en las que se instaló la confusión sexual contra L. botrana muestran que la concentración de feromona en aire va cambiando a lo largo del ciclo de cultivo. Además, se observa que la cubierta vegetal produce un efecto tampón, de manera que la presencia de una masa foliar desarrollada actúa regulando la concentración de feromona en el aire y permite una distribución más homogénea. Mediante la correlación de la velocidad de emisión con los parámetros climáticos, se comprobó que la temperatura y velocidad del viento son parámetros determinantes y que esta dependencia es variable entre distintos tipos de emisores. Por otro lado, se determinó mediante bioensayos electrofisiológicos y de comportamiento que las concentraciones de feromona necesarias para desencadenar mecanismos de confusión no competitiva en machos de L. botrana estaban muy por encima de las cuantificadas en campo, por lo que se concluyó que los principales mecanismos que producen la confusión sexual en condiciones reales son los competitivos. En el caso de las captaciones realizadas en el arrozal, los valores obtenidos de la concentración de feromona en aire sirvieron para estudiar por qué con una colocación más temprana de los emisores se conseguía un mayor efecto en el control de la plaga. Además, se observó que, en este caso, la concentración de feromona en aire guardaba una relación más estrecha con la emisión que proporcionan los emisores de confusión sexual. Este hecho apoya la hipótesis de que una densa masa vegetal, menor en los arrozales que en la viña, puede proteger a la feromona de su lavado por efecto del viento. / [CA] La confusió sexual és el mètode de control de plagues basat en semioquímics que ofereix els millors resultats i té una major acceptació en el mercat. Aquest mètode es basa en l'alliberament de la feromona sexual de l'insecte que es pretén controlar a l'ambient en una quantitat suficient per a provocar un retràs o una reducció de l'aparellament. Els estudis dedicats a l'optimització de la feromona utilitzada, que condiciona en gran mesura el preu de l'ús d'aquesta tècnica, es basen en experiments empírics sobre paràmetres com el número d'emissors utilitzats i la seua distribució, la càrrega inicial de feromona, etc. La quantificació de la feromona en l'aire és un paràmetre més directe i ofereix informació valuosa tant per a realitzar estudis destinats a optimitzar l'ús dels emissors disponibles, com per al desenvolupament de nous dispositius d'emissió amb un menor ús de feromona. En aquesta tesis s'ha desenvolupat una metodologia que permet la quantificació de la concentració de feromona en aire en condicions reals de camp basada en la captació de volàtils de l'aire i el seu anàlisis mitjançant tècniques de cromatografia de gasos i espectrometria de masses. Mitjançant l'ús d'aquesta metodologia s'ha estudiat la quantitat de feromona en aire al llarg del cicle de cultiu en camps tractats amb confusió sexual per a dos espècies diferents d'importància agronòmica en els cultius de la vinya i de l'arròs, el corc del raïm (Lobesia botrana Denis & Schiffermüller) i el cucat de l'arròs (Chilo suppressalis Walker) tractats amb diferents tipus d'emissors. Aquests estudis han servit per a conèixer de quina manera es distribueix la feromona al llarg del temps en relació amb la cinètica dels emissors i quins són els mecanismes implicats en la confusió sexual en condicions reals. A més, també s'ha estudiat la dependència climàtica d'emissors passius en condicions de camp donat que tindrà relació amb la quantitat de feromona en aire i pot repercutir en l'eficàcia del mètode de control. Els resultats obtinguts en les parcel·les en les que es va instal·lar la confusió sexual contra L. botrana mostren que la concentració de feromona en aire va canviant al llarg del cicle de cultiu. A més, s'observa que la coberta vegetal produeix un efecte tampó, de manera que la presència d'una massa foliar desenvolupada actua regulant la concentració de feromona en l'aire i permet una distribució més homogènia. Mitjançant la correlació de la velocitat d'emissió amb els paràmetres climàtics, s'ha comprovat que la temperatura i la velocitat del vent són paràmetres determinants i que esta dependència és variable entre diferents tipus d'emissors. D'altra banda, s'ha determinat mitjançant bioassajos electrofisiològics i de comportament que les concentracions de feromona necessàries per a desencadenar mecanismes de confusió no competitiva en mascles de L. botrana estaven molt per damunt de les quantificades al camp, per la qual cosa es va concloure que els mecanismes principals que produeixen la confusió sexual en condicions reals són els competitius. En el cas de les captacions realitzades en els arrossars, els valors obtinguts de la concentració de feromona en aire van servir per a estudiar per què amb una col·locació més primerenca dels emissors s'aconseguia un major efecte en el control de la plaga. A més, es va observar que, en aquest cas la concentració de la feromona en aire guardava una relació més estreta amb l'emissió que proporcionaven els emissors de confusió sexual. Aquest fet suporta la hipòtesi de que una massa vegetal densa, menor en els arrossars que en les vinyes, pot protegir a la feromona del seu llavat per l'efecte del vent. / [EN] Mating disruption is the pest control method with better acceptation in market due to its results. This method is based on the releasing of the pheromone of the target insect into the environment with enough quantity to delay or to reduce their mating. Optimization-pheromone studies, which condition the use price of this technique a lot, are based on empirical essays about parameters such as the number of dispensers deployed and their distribution, pheromone initial content, etc. Airborne pheromone quantification is a more direct parameter that offers valuable information to do studies to optimize dispenser available use as to develop new dispensers with less pheromone emission. In this work, a methodology that allows the airborne pheromone quantification in real field conditions has been developed based on volatiles airborne sampling and their later analysis with gas chromatography techniques and mass spectrometry. Using this methodology, the airborne pheromone throughout the crop cycle in mating disruption treated fields against different agronomic important species, the European Grapevine Moth (Lobesia botrana Denis & Schiffermüller) and the Rice Stem Borer (Chilo suppressalis Walker), has been studied in vineyards and rice paddies treated with different types of dispensers. These studies have been useful to know how the pheromone is distributed along the time in relation to the dispensers' kinetics and which are the mechanisms involved in mating disruption in real conditions. Moreover, the climatic dependency of the passive dispensers in field conditions has also been studied as it will be related to the airborne pheromone quantity and it can affect the efficacy of the control method. The results show that the airborne pheromone concentration in mating disruption treated fields against L. botrana changes throughout the crop cycle. In addition, it is observed that canopy produces a buffer effect, so the presence of a developed foliage regulates the concentration of the airborne pheromone and allows a more homogeneous distribution. The correlation of emission rate with climatic parameters were useful to check that temperature and wind speed have an influence on dispensers' emission. On the other hand, with electrophysiological and behavioral bioassays, it was determined that higher airborne concentrations were needed to trigger non-competitive mechanisms in L. botrana males. In this way, it was concluded that competitive mechanisms are the ones acting in treated fields In rice paddies air samplings, airborne pheromone concentration data were used to study why an earlier dispensers' deployment achieved a better effect controlling the pest. Furthermore, it was observed a more direct relationship between airborne pheromone with dispensers' emission. This fact supports the hypothesis that thicker foliage, lesser in rice fields than in vineyards, can prevent pheromone from its washing by wind. / Gavara Vidal, A. (2021). Cuantificación de feromonas en aire y su aplicación en métodos de control de plagas [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/165412 / TESIS

Eastern hemlock (Tsuga canadensis) is in decline because of infestation by the invasive hemlock woolly adelgid (Adelges tsugae; ‘HWA’) and, to a lesser extent, the elongate hemlock scale (Fiorinia externa; ‘EHS’). Many conifers respond to insect herbivory by inducing oleoresin-based defenses, however it is unknown whether eastern hemlock is capable of this inducible response. We conducted a plantation setting study of artificially infested saplings to determine if feeding by HWA or EHS induces changes in the tree’s volatile chemistry. The induced changes in volatiles we found were unlike the terpenoid-based defenses of related conifers. Only HWA feeding elevated methyl salicylate, a plant signal for systemic acquired resistance, and benzyl alcohol, a known antimicrobial and aphid deterrent. The influence of environmental conditions and tree life-stage on hemlock volatile chemistry, potentially important factors for wild hemlock populations, is unknown. We investigated whether mature and immature forest trees respond to HWA infestation with the same patterns of volatile production as plantation saplings in full sun and amended soils. HWA induced volatile changes comparable to those of plantation saplings, with many-fold benzenoid increases and no terpenoid-based resinosis. Nearly all volatiles were substantially more abundant in forest than plantation trees, suggesting the effect of site conditions should be addressed in investigations of mechanisms operative in HWA-resistant biotypes of eastern hemlock. Our findings represent the first important step toward understanding the influence of inducible phytochemical responses on hemlock susceptibility to exotic pests, and highlight the possibility of salicylic acid-dependent biosynthetic activity in this gymnosperm system.

A interação entre plantas e seus visitantes florais forma uma rede de interação complexa. Essa rede de interação possui propriedades emergentes que caracterizam a estrutura da rede. A composição, a riqueza e o papel das espécies nas redes de interação podem variar espaço-temporalmente e levar a alteração na estrutura das redes. A estrutura também pode variar de acordo com o grau de dependência entre os pares de espécies. É esperado que interações com elevado grau de dependência mútua variem menos no tempo e no espaço. A interação entre as plantas produtoras de óleo floral e as abelhas coletoras de óleo é de alta dependência mútua, já que as abelhas necessitam do óleo para alimentar as larvas e construir ninhos e são polinizadores mais importantes dessas plantas. O alimento larval destas abelhas é composto por pólen, óleo e néctar. A quantidade de alimento disponível para as larvas pode influenciar o tamanho dos adultos quando emergirem. As espécies de abelhas coletoras de óleo são solitárias, ou seja, não existe contato entre as gerações. Assim uma abelha recém-emergida deve ser capaz de encontrar as fontes de óleo, seguindo algum sinal de atração, que poderia ser através de odores voláteis. No presente trabalho analisamos se a estrutura da rede de interação formada pelas plantas produtoras de óleo floral e seus visitantes coletores de óleo varia espacialmente e temporalmente. Para a análise temporal coletamos dados da interação por dois anos em Itirapina, São Paulo. No estudo de variação espacial comparamos as redes de interação em cinco áreas de cerrado no interior de São Paulo. Em ambos os estudos usamos métricas de redes complexas. Além disso, estudamos a relação entre tamanho de célula de cria e quantidade de alimento disponível para as larvas e tamanho das abelhas adultas ao emergirem, para uma espécie de abelha coletora de óleo: Tetrapedia diversipes. Para isso medimos abelhas e suas células de cria e relacionamos estas medidas. Também manipulamos a quantidade de alimento disponível para as larvas e medimos os adultos emergidos. Por fim, procuramos odores voláteis em Byrsonima intermedia. Coletamos odores voláteis com a técnica de dynamic headspace. Analisamos as coletas com GCMS. A estrutura da rede de interação entre as plantas produtoras de óleo floral e as abelhas coletoras de óleo variou espaço-temporalmente. A análise temporal mostrou que o grau de especialização da rede foi fortemente alterado entre os anos de estudo e que a abundância foi um fator importante para explicar a ocorrência das interações. As espécies que tiveram suas abundâncias alteradas entre os anos também tiveram alteração no número de interações. Na análise espacial observamos que as interações e as espécies compartilhadas entre os locais de estudo foram aquelas com maior grau de interação (generalista). Além das interações e espécies generalistas se manterem nas cinco localidades, as espécies generalistas sustentam as espécies localmente raras. Byrsonima intermedia foi considerada uma espécie super-generalista nas cinco redes analisadas e 77% das interações compartilhadas envolveram esta espécie. A morfometria dos indivíduos de Tetrapedia diversipes estudados foi positivamente correlacionada com o volume da célula de cria e a quantidade de alimento. Quando relacionamos o volume das células de cria com as medidas corpóreas das abelhas verificamos que as abelhas maiores emergiram em células maiores. No entanto essa relação foi fraca. Após o experimento de manipulação de alimento verificamos que as abelhas emergidas de células sem manipulação foram maiores que as abelhas que tiveram o alimento retirado, e que entre as abelhas manipuladas aquelas que receberam mais alimento foram maiores. Nós não encontramos odores voláteis em flores de Byrsonima intermedia. / The plant pollinator interaction forms a complex network. These networks have emergent properties that characterize the structure of network. The number, identity and species role of the network may vary spatio-temporally and lead to changes in the structure of the networks. Moreover, the structure may vary according to the dependence degree of the interacting pairs. It is expected that interactions with a high mutual dependence degree are more stable. The interaction between oil producing plants and oil collecting bees is highly mutual dependence, since bees need oil to feed the larvae and are pollinators of these plants. The larval diet consists of pollen and oil/nectar. The amount of food available to the larvae may influence the adults size. The oil collecting bees are solitary, i.e., there is no contact between generations. Thus, a naive emerged bee should be able to find the oil plants, using some attractive cues that could be volatile odor. In this work we want to answer if the network structure of the interaction between oil producing plants and oil collecting bees varies spatially and temporally. For the temporal analysis we carried out field work for two years at Itirapina, São Paulo. In the study of spatial variation we compare interaction networks in five areas of cerrado. In both studies we use metrics of complex networks. Furthermore, we studied the relation between size of adult bees (Tetrapedia diversipes) and brood cell sizes and the amount of food available for the larvae. We measured the bees and their brood cells and relate it. Also we manipulated the amount of food available for the larvae and we took measures of the adults. Finally, we search for volatile odors in Byrsonima intermedia. We collect volatile odors with the technique of dynamic headspace. We analyzed the samples with GCMS. The network structure of interaction between oil producing plants and oil collecting bees varied spatio-temporally. The temporal analysis showed that the specialization degree of the network changed between the years and that the abundance has a key role to explain the occurrence of interactions. Species that had changed their abundances between years were also changed in the number of interactions. Spatial analysis found out that the interactions and species ubiquitous among the study sites were those that had the greatest interaction degree (generalist specie). Moreover, generalist species maintain the locally rare species. Byrsonima intermedia was regarded a super-generalist specie in the five networks analyzed and 77% of ubiquitous interactions involved this species. The morphometry of Tetrapedia diversipes individuals was positively correlated with the volume of the brood cells and the amount of food. When relating the volume of brood cells with measures of bees we found that larger bees emerged in larger cells. However this relationship was weak. The experiment of handling food showed that bees emerged from control cells were larger than bees that had the food removed, and between the manipulated bees those who received more food became bigger. We did not detect volatile odors in flowers Byrsonima intermedia.

Le métabolisme secondaire joue un rôle écologique majeur dans les interactions des organismes avec leur environnement. Une étude intégrée de la biologie, de l’écologie des organismes et des variations de leur métabolisme est essentielle pour comprendre le rôle des métabolites secondaires au sein des écosystèmes. Or ce type d’approche est rare en milieu marin.Le petit clade d’éponges Homoscleromorpha constitue un vrai potentiel de découverte de nouvelles espèces et de molécules bioactives valorisables. Par ailleurs, leur position de dominance dans certaines communautés benthiques de Méditerranée en faisait un modèle de choix pour démarrer des recherches en écologie chimique marine.Ce travail a débuté avec la description d’une espèce du genre Oscarella, O. balibaloi ainsi que de nouvelles molécules produites par cet organisme. Cette nouvelle espèce avec deux autres espèces communes du même genre, O. tuberculata et O. lobularis constituent parfois de vrais faciès au sein des communautés du coralligène et des grottes semi-obscures. L’étude comparée du cycle de vie de ces Oscarella a montré dans tous les cas une reproduction saisonnière, avec des différences dans les périodes de gamétogénèse et d’émission des larves, et des sensibilités variables face aux changements des conditions de régime thermique. Deux composés majoritaires de type lysophospholipides ont été isolés et caractérisés pour la première fois dans O. tuberculata, et retrouvés dans O. lobularis. Leur rôle potentiel de médiateurs moléculaires impliqués dans le processus de reproduction (embryogenèse et développement) a été proposé, et devra être confirmé par des études expérimentales. Une nouvelle famille de sesterterpènes glycosylés (dénommés balibalosides) a été découverte dans O. balibaloi.Une étude pluriannuelle des variations du métabolisme de ces espèces a été réalisée à travers trois approches complémentaires permettant de tester les modalités d’allocation des ressources à la production de métabolites secondaires. Les patrons de variation des niveaux d’expression de métabolites ciblés, des signatures métaboliques et des bioactivités des extraits d’éponges ont montré une influence significative du cycle de reproduction sur le métabolisme secondaire. Les méthodes globales (métabolomique et bioactivité) ont permis de montrer que le cycle de variation du métabolisme secondaire était marqué par une modification importante de sa production accompagnée par une baisse de bioactivité pendant les périodes les plus coûteuses de la reproduction (reproduction asexuée, embryogenèse et développement larvaire). Ces résultats montrent un compromis d’allocation des ressources entre un métabolisme primaire (la reproduction) et la production des métabolites secondaires, et soutient ainsi la théorie de défense optimale.L’approche de métabolomique s’est avérée un bon indicateur de la chimio-diversité. Appliquée à l’étude des relations inter-spécifiques, cette méthode de chimio-systématique a permis de proposer une classification des espèces méditerranéennes d’Homoscleromorpha. Cette classification soutient les résultats les plus récents de phylogénie moléculaire et propose la restauration de deux anciens clades au sein des Homoscleromorpha: les Plakinidae, un groupe qui ne contient aujourd’hui que des espèces à squelette, et les Oscarellidae qui ne contient que des espèces sans squelette. Les approches développées au cours de cette thèse permettent de nombreuses perspectives en chimio-systématique et écologie chimique marine. L’utilisation des signatures métaboliques peut être transposée à d’autres questions de systématique, particulièrement pour démontrer l’existence d’espèces cryptiques, et pour soutenir des hypothèses phylogénétiques au sein d’autres clades problématiques [...] / Secondary metabolism plays a major ecological role in the interactions between the organisms and their environment. An integral study of the organisms’ biology and ecology and the variations of their metabolism is essential for understanding the role of secondary metabolites in the ecosystems. This kind of approach is rare in the marine environment. Small sponge clade Homoscleromorpha constitutes a real potential for the discovery of new species and potentially bioactive molecules. In addition, its dominance in some Mediterranean benthic communities makes it a good model in marine chemical ecology research. This work has started with a description of new species of Oscarella genus, O. balibaloi. This new species forms sometimes, with two other commun Oscarella species, O. tuberculata and O. lobularis, special facies within the coralligenous and semi-dark cave communities. All three Oscarella species are caraterized by a seasonal reproductive cycle with differences in the period of gametogenesis and larval emission as well as the variation in sensitivity facing the changes in thermal regime. Two major lysophospholipid compounds were isolated and caracterized for the first time in O. tuberculata and confirmed in O. lobularis. Their potential role as signal molecules in the reproduction process (embryogenesis and development) was proposed and should be confirmed by experimental studies. One new familly of glycosilated seterterpens (named balibalosides) was found in O. balibaloi. A pluriannual study of species metabolism was performed using three complementary approaches and enabled to test the models of resource allocation to secondary metabolite production. Variation patterns in the expression level of target metabolites, in the metabolic fingerprints and the bioactivities of sponge extracts reflected the significant influence of the reproductive cycle to the secondary metabolite production. Holisitic approaches (métabolomics and bioactivity) pointed out the important modification in the secondary metabolism variation pattern followed by the decrease in bioactivity during the costly period of reproduction (asexual reproduction, embryogenesis and larval development). These results highlight the trade-off in resource allocation between the primary (reproduction) and secondary metabolism and therefore support the Optimal Defense Theory. Metabolomic approach applied to the study of interspecific relations turned out as a good indicator of chemical diversity which allowed the classification of Mediterranean Homoscleromorpha sepcies. The obtained classification was congruent with recent molecular phylogeny results proposing the restauration of two ancient clades within Homoscleromorpha, the Plakinidae, a group of species possesing skeleton and the Oscarellidae, a group of species lacking skeleton. Approaches developed during my thesis opened a numerous perspectives in chemosystematics and marine chemical ecology. The use of metabolic fingerprints can be transposed to other questions in systematics, particularly to demonstrate the existance of cryptic species and to support phylogenetic hypothesis within other problematic clades. [...]

Predators can have large effects on prey populations and on the structure and function of communities. In addition to direct consumption of prey, predators often cause prey to alter their foraging behavior, habitat selection, and morphology. These non-lethal effects of predators can propagate to multiple trophic levels and often exert equal or larger effects upon communities than those of direct consumption. For non-lethal predatory effects to occur, prey must detect and respond to predation risk. While the importance of information transfer in this process has been realized, few studies explore how prey responses are influenced by predator characteristics and environmental conditions that influence the transmission of cues indicative of predation risk. In this dissertation I investigate factors that influence how a single prey species evaluates and responds to predation risk. Here, I examined: 1) the type and nature of cues prey use to evaluate predator risk; 2) how predator identity, predator diet, and the relative risk of predators influence prey response to predation risk; 3) how hydrodynamic conditions influence the delivery of predator cues; 4) how biogeographic trends in predator distribution influence prey response to predation risk; and 5) how genetic structure might vary according to prey geographic location and habitat. To address these questions, I used a common intertidal model system consisting of the rocky intertidal whelk Nucella lapillus (Linnaeus, 1758) and a suite of its predators, the native rock crab Cancer irroratus (Say, 1817), Jonah crab Cancer borealis (Stimpson, 1859), and the invasive green crab Carcinus maenas (Linnaeus, 1758). Nucella use chemical cues emanating from their most common predator (Carcinus maenas) and crushed conspecifics to evaluate predation risk. Nucella from different habitats experience different levels of predation risk, and Nucella from habitats with high levels of predation had larger antipredatory responses to predator risk cues than Nucella that experienced less predation. These chemical cues indicative of predation risk are influenced by hydrodynamic conditions, and Nucella have the strongest anti-predatory response in flow velocities of u= ~4- 8 cm s^-1. Furthermore, Nucella from geographic regions where green crabs are historically absent did not elicit anti-predatory responses, while Nucella from regions where green crabs are common frequently responded. Findings from my dissertation research demonstrate that prey detection and response to predation risk is highly dependent upon predator identity, predator diet, environmental forces, and biogeographic patterns in predator and prey distributions.

Pest control of cultivated plant species has been usually performed by insecticides, which is undesirable because of economical and environmental concerns, since successive applications affect natural enemies and increase the possibility of development of resistant population toward insecticides. These problems can be minimized with alternative control methods as the use of resistant varieties, use of substances that induce resistance and biological control. Those studies involving the interaction of plant, pest and natural enemies are of fundamental importance. Thus, this study aimed: a) to study the effect of volatile organic compounds in tritrophic interactions between pepper Capsicum spp., the aphid Aphis gossypii and its parasitoid Aphidius colemani; b) to study the role of cis-jasmone in the tritrophic interaction between the pepper, the aphid A. gossypii and the parasitoid A. colemani and its role in activating the defense mechanism of the plant. Pepper varieties were evaluated for resistance to the aphid A. gossypii and their volatiles were collected before and after infestation. Volatiles compounds were tentatively identified by gas chromatography/mass spectrometry. Olfactometry bioassays were performed with volatile regarding the behavior of A. gossypii and A. colemani. The main conclusions obtained in this work were: a) there is genetic variability among genotypes of Capsicumin relation to the release of volatile compounds and in the susceptibility toward A. gossypii; b) genotype Cambuci can be used in breeding programs aiming Capsicum cultivars more resistant to A. gossypii; c) there were significant differences between the effects of volatiles from the two cultivars on behavior of A. gossypii and A. colemani; d) the volatiles emitted by Cambuci cultivar after infestation produced repellent effect on A. gossypii and were attractive to A. colemani; e) the cis-jasmone applied to pepper plants provided emission of volatiles that had repellent action on the A. gossypii and attractive one to A. colemani; f) the genetic variability between genotypes, after infestation indicates that volatile organic compounds present as variables can be used for selection and development of bell pepper cultivars resistant to the aphid A. gossypii. / O controle de pragas das espécies vegetais cultivadas tem sido normalmente realizado por meio de inseticidas, o que é indesejável tanto por motivos econômicos quanto ambientais, já que as aplicações sucessivas afetam os inimigos naturais e aumentam a possibilidade de desenvolvimento de populações da praga resistentes aos inseticidas. Esses problemas podem ser minimizados com métodos alternativos de controle como o emprego de variedades resistentes, o uso de substâncias indutoras e o controle biológico. Para isso, estudos envolvendo a interação planta, praga e inimigo natural são de fundamental importância. Dessa forma, este trabalho teve como objetivos: a) Estudar a ação dos compostos orgânicos voláteis na interação tritrófica entre o pimentão Capsicum spp., o pulgão Aphis gossypiie seu parasitóide Aphidiuscolemani; b) Estudar a ação da cis-jasmona na interação tritrófica entre o pimentão, o pulgão A. gossypii e o parasitóide A. colemani e seu papel na ativação do mecanismo de defesa do vegetal. Variedades de pimentão foram avaliadas em relação à resistência ao pulgão A. gossypii e os seus compostos voláteis foram coletados antes e após a infestação. Os compostos voláteis foram tentativamente identificados por cromatografia gasosa/espectrometria de massas. Bioensaios de olfatometria foram realizados com os compostos voláteis em relação ao comportamento de A. gossypii e A. colemani. As principais conclusões obtidas neste trabalho foram: a) Existe variabilidade genética entre os genótipos de Capsicum em relação à emissão de compostos voláteis e em relação à susceptibilidade ao A. gossypii; b) O genótipo Cambuci poderá ser utilizado em programas de melhoramento genético visando cultivares de Capsicum mais resistentes ao A. gossypii; c) Houve diferenças significativas entre os efeitos dos compostos voláteis das duas cultivares sobre os comportamentos de A. gossypii e de A. colemani; d) Os compostos voláteis emitidos pela cultivar Cambuci após a infestação proporcionaram efeito repelente a A. gossypii e atrativo a A. colemani; f) A cis-jasmona aplicada sobre plantas de pimentão induziu a emissão e/ou produção de compostos voláteis que teve ação de repelência a A. gossypii e ação atraente para A. colemani; i) A variabilidade genética entre os genótipos, após a infestação, indica que os compostos orgânicos voláteis apresentam-se como variáveis que podem ser utilizadas para seleção e desenvolvimento de cultivares de pimentão resistente ao pulgão A. gossypii.

The aim of this work was to study the effect of Volatile Organic Compounds (VOCs) released by cattle of different breeds on the behavior of the horn fly (Haematobia irritans). This ectoparasite is of great economic importance because it causes damage to various livestock worldwide. The study began with the implementation of a breeding place for horn flies in the laboratory at the Federal University of Alagoas in order to perform advanced studies with this parasite, as well as to follow the development of the egg to adult. Three breedings methods were used in order to obtain the greater emergency index of H. irritans fly in laboratory. Afterwards, odors released by cattle breeds Gyr, Holstein, Brown Swiss, Nellore and Gyr (both sexes) were taken followed by the extraction of the material collected with the aid of bidestiled hexane and analysis by Gas Chromatography (GC), Gas Chromatography coupled to Mass Spectrometry (GC/MS) in all breeds; Eletroantenography Gas Chromatography (GC/EAG) performed with the chromatogram with the highest number of peaks and behavioral bioassays. The behavioral bioassays with the horn fly were performed with extracts from animal and synthetic standards identified in GC/EAD, using an olfactometer type Y. In addition, we investigated whether there are differences on VOCs released from the different genetic groups. With regard to the breeding place, in the first creation, horn flies after emergence were counted and the result was 18.61% of emergency. In the second creation, the percentage of emerged flies was 55.56% and in the third was 78.22%, considered, thus, the most appropriate method for rearing H. irritans in laboratory, when the development was within a cooling chamber. Analysis of the GC chromatograms of the Brown Swiss breed showed that the collection of VOCs in animals was efficient since most of the compounds was shown to be present in all samples. The qualitative GC analysis of all races had shown that there was not a large variation with respect to VOCs. The analysis of GC/MS confirmed the difference on compounds between the races, and nine of them were common in all races. Among them, camphene, 2-ethylhexanal, 2-heptenal, 1-octen-3-one, 1-octen-3-ol, octan-3-one, octanal, 2,2,8-trimethyldecane and 2-phenylethyl butyrate. All VOCs obtained in the analyses mentioned above were identified by their Kovats indices indexes (KI). The results of the extracts’ aeration bioassays have shown that insects are attracted by volatiles from both sexes of the European breeds and mixed Girolando. In the bioassays performed with synthetic standards, only butyl acetate showed significant responses at concentrations of 10-7, 10-6 and 10-5 mg/mL. VOCs obtained by GC/MS were similar between breeds and mixed European and otherwise distinct from the Indian races. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / O objetivo deste trabalho foi estudar o efeito dos Compostos Orgânicos Voláteis (COVs) liberados por bovinos de diferentes raças sobre o comportamento da mosca-dos-chifres (Haematobia irritans). Esse ectoparasita é de grande importância econômica, por causar diversos danos à pecuária mundial. O estudo teve início com a implantação de um criatório de moscasdos-chifres em laboratório, na Universidade Federal de Alagoas, visando à realização de estudos avançados com esse parasita, assim como acompanhar o desenvolvimento ovo-adulto. Três criações foram utilizadas para obtenção de um maior número de emergência da mosca H. irritans em laboratório. Posteriormente, foram realizadas coletas de odores exalados por bovinos das raças Girolando, Holandesa, Pardo-Suíça, Nelore e Gir (de ambos os sexos), seguindo-se extração, por hexano bidestilado, do material coletado e análises por Cromatografia Gasosa (CG); Cromatografia Gasosa acoplada à Espectrometria de Massas (CG/EM) em todas as raças estudadas; Cromatografia Gasosa acoplada a Eletroantenografia (CG/EAG) com o cromatograma que apresentou o maior número de picos e bioensaios comportamentais. Os bioensaios comportamentais com a mosca-dos-chifres foram realizados com os extratos oriundos dos animais e com padrões sintéticos identificados no CG/EAG usando olfatômetro tipo Y. Além disso, foi investigado se existe diferença dos COVs liberados entre os diferentes grupos genéticos. Com relação ao criatório de mosca-dos-chifres, após emergência, as moscas foram contadas e o resultado foi de 18,61 % de emergência, na primeira criação. Na segunda criação, a porcentagem de moscas emergidas foi de 55,56 % e na terceira criação a emergência foi de 78,22 %, sendo considerado, o método mais adequado para criação de H. irritans em laboratório, quando a criação foi desenvolvida dentro de uma câmara de refrigeração. A análise dos resultados de CG da raça Pardo-Suíça revelou que a coleta dos COVs em animais foi eficiente já que a maior parte dos compostos repetiu-se em todas as amostras analisadas. A análise em CG de todas as raças mostra que não houve uma grande variação qualitativa com relação aos COVs das amostras analisadas. A análise do CG/EM, confirmou a diferença dos compostos entre as raças, sendo que, nove foram comuns em todas as raças. Entre eles, canfeno, 2-etil-hexanal, 2-heptenal, 1-octen-3-ona, 1-octen-3-ol, octan-3-ona, octanal, 2,2,8-trimetildecano e butirato de 2-feniletila. Todos os COVs obtidos nas análises citadas acima foram identificados através do Índice de Kóvats (KI). Os resultados obtidos com os bioensaios dos extratos da aeração mostraram que os insetos foram atraídos pelos voláteis de ambos os sexos das raças europeias e da mestiça Girolando. Os bioensaios realizados com os padrões sintéticos mostraram que apenas o acetato de butila apresentou respostas significativas nas concentrações de 10-7,10-6 e 10-5 mg/mL. Os COVs obtidos por CG/EM foram similares entre as raças europeias e a mestiça e por outro lado distintos das raças indianas.

A interação entre plantas e seus visitantes florais forma uma rede de interação complexa. Essa rede de interação possui propriedades emergentes que caracterizam a estrutura da rede. A composição, a riqueza e o papel das espécies nas redes de interação podem variar espaço-temporalmente e levar a alteração na estrutura das redes. A estrutura também pode variar de acordo com o grau de dependência entre os pares de espécies. É esperado que interações com elevado grau de dependência mútua variem menos no tempo e no espaço. A interação entre as plantas produtoras de óleo floral e as abelhas coletoras de óleo é de alta dependência mútua, já que as abelhas necessitam do óleo para alimentar as larvas e construir ninhos e são polinizadores mais importantes dessas plantas. O alimento larval destas abelhas é composto por pólen, óleo e néctar. A quantidade de alimento disponível para as larvas pode influenciar o tamanho dos adultos quando emergirem. As espécies de abelhas coletoras de óleo são solitárias, ou seja, não existe contato entre as gerações. Assim uma abelha recém-emergida deve ser capaz de encontrar as fontes de óleo, seguindo algum sinal de atração, que poderia ser através de odores voláteis. No presente trabalho analisamos se a estrutura da rede de interação formada pelas plantas produtoras de óleo floral e seus visitantes coletores de óleo varia espacialmente e temporalmente. Para a análise temporal coletamos dados da interação por dois anos em Itirapina, São Paulo. No estudo de variação espacial comparamos as redes de interação em cinco áreas de cerrado no interior de São Paulo. Em ambos os estudos usamos métricas de redes complexas. Além disso, estudamos a relação entre tamanho de célula de cria e quantidade de alimento disponível para as larvas e tamanho das abelhas adultas ao emergirem, para uma espécie de abelha coletora de óleo: Tetrapedia diversipes. Para isso medimos abelhas e suas células de cria e relacionamos estas medidas. Também manipulamos a quantidade de alimento disponível para as larvas e medimos os adultos emergidos. Por fim, procuramos odores voláteis em Byrsonima intermedia. Coletamos odores voláteis com a técnica de dynamic headspace. Analisamos as coletas com GCMS. A estrutura da rede de interação entre as plantas produtoras de óleo floral e as abelhas coletoras de óleo variou espaço-temporalmente. A análise temporal mostrou que o grau de especialização da rede foi fortemente alterado entre os anos de estudo e que a abundância foi um fator importante para explicar a ocorrência das interações. As espécies que tiveram suas abundâncias alteradas entre os anos também tiveram alteração no número de interações. Na análise espacial observamos que as interações e as espécies compartilhadas entre os locais de estudo foram aquelas com maior grau de interação (generalista). Além das interações e espécies generalistas se manterem nas cinco localidades, as espécies generalistas sustentam as espécies localmente raras. Byrsonima intermedia foi considerada uma espécie super-generalista nas cinco redes analisadas e 77% das interações compartilhadas envolveram esta espécie. A morfometria dos indivíduos de Tetrapedia diversipes estudados foi positivamente correlacionada com o volume da célula de cria e a quantidade de alimento. Quando relacionamos o volume das células de cria com as medidas corpóreas das abelhas verificamos que as abelhas maiores emergiram em células maiores. No entanto essa relação foi fraca. Após o experimento de manipulação de alimento verificamos que as abelhas emergidas de células sem manipulação foram maiores que as abelhas que tiveram o alimento retirado, e que entre as abelhas manipuladas aquelas que receberam mais alimento foram maiores. Nós não encontramos odores voláteis em flores de Byrsonima intermedia. / The plant pollinator interaction forms a complex network. These networks have emergent properties that characterize the structure of network. The number, identity and species role of the network may vary spatio-temporally and lead to changes in the structure of the networks. Moreover, the structure may vary according to the dependence degree of the interacting pairs. It is expected that interactions with a high mutual dependence degree are more stable. The interaction between oil producing plants and oil collecting bees is highly mutual dependence, since bees need oil to feed the larvae and are pollinators of these plants. The larval diet consists of pollen and oil/nectar. The amount of food available to the larvae may influence the adults size. The oil collecting bees are solitary, i.e., there is no contact between generations. Thus, a naive emerged bee should be able to find the oil plants, using some attractive cues that could be volatile odor. In this work we want to answer if the network structure of the interaction between oil producing plants and oil collecting bees varies spatially and temporally. For the temporal analysis we carried out field work for two years at Itirapina, São Paulo. In the study of spatial variation we compare interaction networks in five areas of cerrado. In both studies we use metrics of complex networks. Furthermore, we studied the relation between size of adult bees (Tetrapedia diversipes) and brood cell sizes and the amount of food available for the larvae. We measured the bees and their brood cells and relate it. Also we manipulated the amount of food available for the larvae and we took measures of the adults. Finally, we search for volatile odors in Byrsonima intermedia. We collect volatile odors with the technique of dynamic headspace. We analyzed the samples with GCMS. The network structure of interaction between oil producing plants and oil collecting bees varied spatio-temporally. The temporal analysis showed that the specialization degree of the network changed between the years and that the abundance has a key role to explain the occurrence of interactions. Species that had changed their abundances between years were also changed in the number of interactions. Spatial analysis found out that the interactions and species ubiquitous among the study sites were those that had the greatest interaction degree (generalist specie). Moreover, generalist species maintain the locally rare species. Byrsonima intermedia was regarded a super-generalist specie in the five networks analyzed and 77% of ubiquitous interactions involved this species. The morphometry of Tetrapedia diversipes individuals was positively correlated with the volume of the brood cells and the amount of food. When relating the volume of brood cells with measures of bees we found that larger bees emerged in larger cells. However this relationship was weak. The experiment of handling food showed that bees emerged from control cells were larger than bees that had the food removed, and between the manipulated bees those who received more food became bigger. We did not detect volatile odors in flowers Byrsonima intermedia.