Abstract Vision is capable of providing an animal with a wealth of information very fast. Visually guided behaviours are numerous, ranging from foraging to navigation. Vision can be quite reliable in bright light, but the signals produced by the photoreceptors become progressively more unreliable with falling light intensities. In this thesis the usefulness of a novel virtual reality-based environment for insect vision research is reviewed, and the low-light vision of the American cockroach, Periplaneta americana, is assessed using the optomotor behavioural paradigm and intracellular photoreceptor recordings. The optomotor reaction is visual behaviour where an animal responds to a rotation of its environment by following the movement of its surroundings with its eyes or - like insects - by rotating its body in the direction of the movement. Placing the cockroach on a trackball in the middle of the virtual reality apparatus and projecting a rotating pattern of vertical stripes around it invariably causes an optomotor reaction if the cockroach is able to see the moving pattern. Presenting the cockroaches with the stimulus pattern at different low light levels and observing their abilities to follow the movement reveal the lowest light intensity at which they are able to use vision in guiding their behaviour. The compound eye photoreceptor signals at this behavioural threshold consist of singlephoton absorption events called ‘bumps’ at the extremely low rate of one bump every ten seconds. Furthermore, the role of the simple eyes or ocelli in the low-light vision of the cockroach is studied in the virtual reality by covering the compound eyes, the ocelli, or both. The ocelli seem to measure the light intensity and communicate this information to the compound eyes, and also have a direct effect on the general activity level of the cockroach.

As abelhas utilizam sinais visuais e olfatórios para encontrar plantas das quais utilizam recursos florais. Algumas abelhas adquiriram hábitos crepuscular ou noturno e forrageiam durante períodos de pouca luminosidade. Algumas espécies de abelhas noturnas são conhecidas por possuírem adaptações morfológicas do sistema visual que lhes permitem o voo noturno, e assim facilitam o encontro de plantas que podem ser utilizadas como recursos. No presente estudo investigamos se espécies crepusculares Megalopta sodalis, Megommation insigne e Ptiloglossa latecalcarata, que utilizam Campomanesia phaea como recurso, e possuem adaptações na morfologia externa do sistema visual. A hipótese principal é que seriam encontrados olhos compostos, omatídeos e ocelos maiores, assim como menor quantidade de omatídeos nos olhos compostos quando comparadas às abelhas diurnas. Para tanto, medimos o comprimento, área e número de omatídeos dos olhos compostos, assim como o diâmetro dos omatídeos e ocelos. A distância intertegular foi medida para ter um controle do tamanho corporal. Além das abelhas crepusculares acima citadas, utilizamos as abelhas diurnas Bombus brasiliensis, Bombus morio, Melipona bicolor e Euglossa cordata para comparação. Para a medida dos olhos fizemos um molde de esmalte e a partir deste obtivemos imagens que foram analisadas utilizando-se o software ImageJ e Matlab. Para as outras medidas, foram obtidas imagens em estereomicroscopio que foram analizadas com o ImageJ. Utilizamos a análise estatística de permutação para ver se havia diferença entre as abelhas crepusculares e diurnas, e correlação de Spearman para ver se a medida estava correlacionada à distância intertegular. Foi realizado um levantamento das espécies com registro de interação com abelhas crepusculares e noturnas e de suas características florais com uma respectiva análise descritiva. As abelhas crepusculares deste estudo possuem o diâmetro dos ocelos e omatídeos maiores e olhos compostos com maior comprimento e área, e menor número de omatídeos. Algumas variáveis estão correlacionadas com a distância intertegular. As flores visitadas por abelhas noturnas possuem em sua maioria cores claras, perfume acentuado e são odoríferas. As abelhas crepusculares deste estudo possuem adaptações na morfologia externa, o que lhes permite o voo no período de pouca luminosidade. Algumas espécies de abelhas que forrageiam em período de pouca luminosidade visitaram flores de cores fortes e uma não odorífera, isso pode estar relacionado à capacidade de reconhecer cores em ambientes pouco iluminados. Algumas espécies de abelhas forrageiam durante o dia e a noite, essa plasticidade do comportamento pode ser um caminho pelo qual caracteres vantajosos para esse ambiente sejam selecionados. Para as plantas, ter as abelhas noturnas como polinizadoras pode ser vantojoso. Então plantas que possuem sinais reconhecidos pelas abelhas noturnas podem se beneficiar com a polinização noturna, evitando o disperdício de pólen com as abelhas diurnas. A maioria das abelhas foi generalista na utlilização do recurso, mas parece haver preferência por certas espécies de plantas / The bees use visual cues and olfactory to find plants which own floral resources. Some bees acquired crepuscular or nocturnal habits and foraging during periods of low light. Some nocturnal bees species are recognized to possess morphological adaptations of the visual system that enable them to practice the night flight, and thus facilitate the matching of plants that can be used as resources. In the present study we investigated whether crepuscular species Megalopta sodalis, Megommation insigne e Ptiloglossa latecalcarata, using Campomanesia phaea as a resource, have adaptations in the external morphology of the visual system. The main hypothesis was that the eyes were composed of ommatidia and larger ocelli as well as lower amount of ommatidia in the compound eyes when compared to daytime bees. Therefore, we measure the length, the area and number of ommatidia of the compound eye and also the diameter of the ommatidia, ocelli, and intertegular distance to have a control of body size. In addition to the crepuscular bees mentioned above, we used the diurnal bees Bombus brasiliensis, Bombus morio, Euglossa cordata, and Melipona bicolor for comparison. For the measurement of eyes, we made a nail polish mold and from this mold was obtained images which were analyzed using ImageJ and Matlab software. For other measures, we obtained images in stereomicroscope that were analyzed only using ImageJ. We use the statistical analysis of permutation to observe if there was any difference between the crepuscular and diurnal bees, and Spearman correlation to see if the measure was correlated with distance intertegular. In addition, we conducted a survey of species interaction with record crepuscular and nocturnal bees and their floral characteristics with a descriptive analisys. The crepuscular bees in this research have lager diameter of omatidea and ocelli, and larger area and length of compound eyes, and less number of omatidea per eye. Most of the flowers visited by nocturnal bees have pale color, scent and nocturnal anthesis. Some bee species that forage in low light visit flowers with strong color, and one bee visited flower without scent, this can be related with capacibility to recoginized colors in environments with low light. Some bees forage during day and night, this phenotypic plasticity of behavior can be a way that advantageous characters for this environment are selected. For plants can be advantageous. Then plants that posses sinals recognized by nocturnal and crepuscular bees can be benefited through nocturnal pollination, avoiding daylight bees waste their polen. The most of bees were generalists in their utilization of flower resource but seems to have preference for some plant species

As abelhas utilizam sinais visuais e olfatórios para encontrar plantas das quais utilizam recursos florais. Algumas abelhas adquiriram hábitos crepuscular ou noturno e forrageiam durante períodos de pouca luminosidade. Algumas espécies de abelhas noturnas são conhecidas por possuírem adaptações morfológicas do sistema visual que lhes permitem o voo noturno, e assim facilitam o encontro de plantas que podem ser utilizadas como recursos. No presente estudo investigamos se espécies crepusculares Megalopta sodalis, Megommation insigne e Ptiloglossa latecalcarata, que utilizam Campomanesia phaea como recurso, e possuem adaptações na morfologia externa do sistema visual. A hipótese principal é que seriam encontrados olhos compostos, omatídeos e ocelos maiores, assim como menor quantidade de omatídeos nos olhos compostos quando comparadas às abelhas diurnas. Para tanto, medimos o comprimento, área e número de omatídeos dos olhos compostos, assim como o diâmetro dos omatídeos e ocelos. A distância intertegular foi medida para ter um controle do tamanho corporal. Além das abelhas crepusculares acima citadas, utilizamos as abelhas diurnas Bombus brasiliensis, Bombus morio, Melipona bicolor e Euglossa cordata para comparação. Para a medida dos olhos fizemos um molde de esmalte e a partir deste obtivemos imagens que foram analisadas utilizando-se o software ImageJ e Matlab. Para as outras medidas, foram obtidas imagens em estereomicroscopio que foram analizadas com o ImageJ. Utilizamos a análise estatística de permutação para ver se havia diferença entre as abelhas crepusculares e diurnas, e correlação de Spearman para ver se a medida estava correlacionada à distância intertegular. Foi realizado um levantamento das espécies com registro de interação com abelhas crepusculares e noturnas e de suas características florais com uma respectiva análise descritiva. As abelhas crepusculares deste estudo possuem o diâmetro dos ocelos e omatídeos maiores e olhos compostos com maior comprimento e área, e menor número de omatídeos. Algumas variáveis estão correlacionadas com a distância intertegular. As flores visitadas por abelhas noturnas possuem em sua maioria cores claras, perfume acentuado e são odoríferas. As abelhas crepusculares deste estudo possuem adaptações na morfologia externa, o que lhes permite o voo no período de pouca luminosidade. Algumas espécies de abelhas que forrageiam em período de pouca luminosidade visitaram flores de cores fortes e uma não odorífera, isso pode estar relacionado à capacidade de reconhecer cores em ambientes pouco iluminados. Algumas espécies de abelhas forrageiam durante o dia e a noite, essa plasticidade do comportamento pode ser um caminho pelo qual caracteres vantajosos para esse ambiente sejam selecionados. Para as plantas, ter as abelhas noturnas como polinizadoras pode ser vantojoso. Então plantas que possuem sinais reconhecidos pelas abelhas noturnas podem se beneficiar com a polinização noturna, evitando o disperdício de pólen com as abelhas diurnas. A maioria das abelhas foi generalista na utlilização do recurso, mas parece haver preferência por certas espécies de plantas / The bees use visual cues and olfactory to find plants which own floral resources. Some bees acquired crepuscular or nocturnal habits and foraging during periods of low light. Some nocturnal bees species are recognized to possess morphological adaptations of the visual system that enable them to practice the night flight, and thus facilitate the matching of plants that can be used as resources. In the present study we investigated whether crepuscular species Megalopta sodalis, Megommation insigne e Ptiloglossa latecalcarata, using Campomanesia phaea as a resource, have adaptations in the external morphology of the visual system. The main hypothesis was that the eyes were composed of ommatidia and larger ocelli as well as lower amount of ommatidia in the compound eyes when compared to daytime bees. Therefore, we measure the length, the area and number of ommatidia of the compound eye and also the diameter of the ommatidia, ocelli, and intertegular distance to have a control of body size. In addition to the crepuscular bees mentioned above, we used the diurnal bees Bombus brasiliensis, Bombus morio, Euglossa cordata, and Melipona bicolor for comparison. For the measurement of eyes, we made a nail polish mold and from this mold was obtained images which were analyzed using ImageJ and Matlab software. For other measures, we obtained images in stereomicroscope that were analyzed only using ImageJ. We use the statistical analysis of permutation to observe if there was any difference between the crepuscular and diurnal bees, and Spearman correlation to see if the measure was correlated with distance intertegular. In addition, we conducted a survey of species interaction with record crepuscular and nocturnal bees and their floral characteristics with a descriptive analisys. The crepuscular bees in this research have lager diameter of omatidea and ocelli, and larger area and length of compound eyes, and less number of omatidea per eye. Most of the flowers visited by nocturnal bees have pale color, scent and nocturnal anthesis. Some bee species that forage in low light visit flowers with strong color, and one bee visited flower without scent, this can be related with capacibility to recoginized colors in environments with low light. Some bees forage during day and night, this phenotypic plasticity of behavior can be a way that advantageous characters for this environment are selected. For plants can be advantageous. Then plants that posses sinals recognized by nocturnal and crepuscular bees can be benefited through nocturnal pollination, avoiding daylight bees waste their polen. The most of bees were generalists in their utilization of flower resource but seems to have preference for some plant species

L’horloge circadienne permet de régler avec précision les anticipations physiologiques et comportementales face à un environnement perpétuellement oscillant entre jour et nuit. Cette capacité endogène n’est utile que si les processus biologiques restent synchronisés sur le temps solaire. La lumière représente le stimulus le plus efficace pour informer l’horloge des cycles environnementaux.
Chez la drosophile (Drosophila melanogaster) la synchronisation des rythmes veille/sommeil par la lumière est assurée par la molécule photosensible CRYPTOCHROME et par le système visuel. Alors que le cryptochrome agit dans les neurones d'horloges, le système visuel renseigne ces derniers par des voies qui restent à découvrir. La drosophile possède trois organes photorécepteurs, l'oeil composé, les ocelles et l'eyelet de Hofbauer-Buchner, qui expriment chacun une ou plusieurs rhodopsines. La cascade de phototransduction activée par la lumière dépend de la phospholipase C-ß NORPA et conduit à une libération d’histamine.
Dans notre étude, nous avons tenté de caractériser la contribution de chaque rhodopsine dans l’entraînement circadien, mais également de déterminer leur contribution norpA-dépendante en condition de faible lumière.
L’analyse de mutants a montré que les 6 rhodopsines du système visuel constituaient les seules molécules photosensibles capables d’informer l’horloge et que la RH2 et la RH5 seules étaient capables d’entraîner l’horloge en fonction des conditions expérimentales. Nous avons également pu mettre en évidence le fait que les RH1, RH3, RH4 et RH6 utilisaient une voie NORPA-dépendante pour informer l’horloge, alors que la RH2 ne semblait pas le faire. Des doutes subsistent quant à l’existence d’une voie NORPA- dépendante de la RH5 pour informer l’horloge. Nous avons également caractérisé la contribution des récepteurs à l’histamine ORT et HISCL1 dans les processus circadiens: en l'absence de cryptochrome, chacun des deux récepteurs suffit à synchroniser l'horloge et la perte des deux rend les mouches circadiennement aveugles De plus, nous avons constaté que la connexion des photorécepteurs à l’horloge ne se faisait pas directement mais par l’intermédiaire de voies glutamatergiques ou cholinergiques. L’ensemble de ce travail a permis de faire une 1er ébauche des circuits nécessaires à la transmission de l’information lumineuse à l’horloge cérébrale et d’identifier les opsines ainsi que les interneurones impliqués. / The circadian clock allowed physiologic and behavioural anticipation against the day/night oscillation. Light is the most powerful clue for living organism. In the fly Drosophila melanogaster, the rest-activity is synchronized by light and pass through the cryptochrome and the visual system. CRYPTOCHROME act directly in the clock neurons to inform the clock but little is known about the visual system. Drosophila posses tree structures: the ocelli, the compound eye and the eyelet of Hofbauer-Buchner, each structure expressed one or multiple rhodopsins. The phototransduction cascade is activated by light and depend one a phospholipase C-ß NORPA, this lead to histamine realised. Study of mutants show that the 6 rhodopsines represent the only photo-sensible molecule for the clock and the RH2 and the RH5 alone could entrain the clock. We have also find that the RH1, RH3, RH4 and RH6 use a NORPA-dependant way to inform the clock whereas the RH2 does not. Some doubt is still present regarding the RH5 NORPA-dependant way. We have determined that the two-histamines receptor ORT and HISCL1 are involved in the circadian process. Besides, we have shown that there is no direct connexion between the clock and the photoreceptors but the information is relay on a glutamatergique and a cholinegique pathway. This thesis draws the circuit by which the light informed the clock and identified the opsines and the interneurons involved.

Les plumes d'oiseaux abritent de nombreux microorganismes qui pourraient être acquis dans l'environnement, ces microorganismes pouvant exercer une sélection intense sur leurs hôtes en réduisant leur fécondité et leur survie. Plusieurs taxons bactériens qui vivent sur des plumes ont la capacité de dégrader la kératine des plumes et causent des dommages à leur structure et peuvent modifier aussi leur coloration. Les oiseaux utilisent des signaux visuels tels que des couleurs vives ou des ornementations exagérées pour la communication socio-sexuelle ainsi que la reconnaissance des espèces. Seuls les individus en bonne santé sont capables de produire des caractères sexuels secondaires exagérés et restent résistants aux parasites débilitants. Le paon (Pavo cristatus) est une espèce polygame qui a plusieurs décorations exagérées, les caractères sexuels secondaires les plus remarquables du paon sont leur traîne décorée avec des ocelles magnifiques qui contiennent trois couleurs irisées différentes. Grâce à une technique basée sur la culture, j'ai isolé la communauté bactérienne des plumes de différentes parties colorées des ocelles de la traîne du paon. L'étude révèle qu'il y a eu une répartition hétérogène des bactéries parmi les différentes parties colorées des ocelles. L'abondance et la prévalence des taxa bactériens spécifiques étaient liées au degré de dégradation des plumes, à l'expression de différents caractères sexuels secondaires, à des changements dans la coloration des ocelles et à l'augmentation de la croissance quotidienne des plumes. En outre, nous avons constaté un petit effet de l'expression de caractères sexuels secondaires sur la proportion sexuelle des couvées avec un biais en faveur des individus masculins. Les travaux présentés dans cette thèse fournissent des preuves que les ocelles de plumes peuvent être considérés comme un signal fiable de la diversité et de l'abondance de bactéries chez le paon. En conséquence, ils représentent une indication pour la qualité individuelle, ce qui permet aux femelles de choisir des mâles avec une communauté bactérienne spécifique. / Bird feathers harbour numerous microorganisms that could be acquired from the surrounding environment, these microorganisms may exert intense selection on their hosts by reducing fecundity and survivorship. Several bacterial taxa that live on feathers have the ability to degrade feather keratin and cause damage to feather structure and may alter the feather colouration. Birds use visual signals such as bright colours or exaggerated ornamentation for socio-sexual communication as well as species recognition. Only healthy individuals are able to produce exaggerated secondary sexual characters and still remain resistant to debilitating parasites. Peacocks (Pavo cristatus) is a polygamous species that have different exaggerated ornamentation, the most notable secondary sexual characters of the peacock are their long-decorated trains that comprise the magnificent ocelli which contain three different iridescent colours. Through a culture based technique we isolate feather bacterial community from differently coloured parts of the ocelli of the peacock’s train. The study reveals that there was a heterogeneous distribution of bacteria among the differently coloured parts of ocelli. The abundance and prevalence of specific bacterial taxa was related to the degree of feather degradation, expression of different secondary sexual character, changes in ocelli colouration and daily growth increment. Furthermore, we found a small effect of the expression of secondary sexual characters on biasing of brood sex ratio towards production of more sons than daughters. The work presented in this thesis provide evidence that feather ocelli may consider as a reliable signal of the diversity and the abundance of bacteria in peacock and in consequence indication for the individual quality and that allowing the choosy females to pick males with a specific bacterial community.