Submitted by Gizele Lima (gizele.lima@inpa.gov.br) on 2017-04-11T19:23:50Z No. of bitstreams: 2 Gyrinidae Coleoptera da Amazonia Central Taxonomia e Bionomia.pdf: 4262420 bytes, checksum: 3148c49133cbdbb365ffd1ff23849b5d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-04-11T19:23:50Z (GMT). No. of bitstreams: 2 Gyrinidae Coleoptera da Amazonia Central Taxonomia e Bionomia.pdf: 4262420 bytes, checksum: 3148c49133cbdbb365ffd1ff23849b5d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-04-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Gyrinidae is one of the less-studied aquatic Coleoptera families in Brazil. In addition, information about species in the state of Amazonas has been restricted to species descriptions and species records that are brief and often obsolete. The aim of the present study was therefore to increase knowledge of the taxonomy and biology of Gyrinidae species in Central Amazonia. Samples were collected in six municipalities in the State: Manaus, Presidente Figueiredo, Iranduba, Careiro da Várzea, Barcelos and Rio Preto da Eva. Additional material from INPA’s Aquatic Insects Laboratory was also used. Sampling was done with an entomological sweep net in lakes, rivers, streams and pools. Some adults and eggs were transported in plastic containers with water for rearing in the laboratory. Two larval stages and the eggs of Gyretes nubilus Ochs, 1965 were associated by means of oviposition under laboratory conditions. Of 12 species sampled in the study area, nine belonging to the genus Gyretes Brullé and three to Gyrinus Müller. The species recorded were characterized morphologically and bionomic information was provided. The mitochondrial gene Cytochrome oxidase subunit I (COI) was used for the molecular association between adults and immatures of the species Gyretes nubilus and G. minax. The eggs of these species were described using optical and scanning electron microscopy. The first and second larval stages of G. nubilus were described and adults of 12 species were redescribed. This study represents the first contribution to knowledge of the immatures of Gyrinidae species in Brazil. The study increases knowledge about the diversity of species of this family in Central Amazonia, in addition to providing detailed morphological characterizations of the species sampled in the study area, which will facilitate the identification of these species. / Gyrinidae é uma das famílias de Coleoptera aquáticos pouco estudados no Brasil. No Amazonas, estudos sobre essa família restringem-se a descrições originais breves e antigas, e registros esporádicos de espécies. Em vista disso, o objetivo deste estudo foi incrementar o conhecimento sobre a taxonomia e biologia de espécies de Gyrinidae na Amazônia Central. As coletas foram realizadas em seis municípios do Amazonas: Manaus, Presidente Figueiredo, Iranduba, Careiro da Várzea, Barcelos e Rio Preto da Eva. Também foi incluído na análise material adicional presente no Laboratório de Insetos Aquáticos do Instituto Nacional de Pesquisas da Amazônia (INPA). As coletas de imaturos e adultos foram feitas com o auxílio de uma de rede entomológica aquática, em lagos, rios, igarapés e poças. Alguns adultos e ovos foram levados para o laboratório em recipientes plásticos com água para criação em laboratório. Ovos e larvas de dois estádios de Gyretes nubilus Ochs foram associados por meio das observações bionômicas em condições de laboratório. Foram coletados exemplares de 12 espécies de Gyrinidae na área estudada, dez pertencentes a Gyretes Brullé e dois a Gyrinus Müller. As espécies registradas foram caracterizadas morfologicamente e informações bionômicas foram fornecidas. O gene mitocondrial Citocromo Oxidase subunidade I (COI) foi utilizado para realizar a associação molecular de adultos e imaturos de Gyretes minax Ochs e Gyretes nubilus. A partir desta associação foram descritos, os ovos de duas espécies, G. minax e G. nubilus através de microscopia óptica e eletrônica de varredura, também foram descritas larvas de primeiro e segundo estádios de G. nubiluse os adultos de 12 espécies foram redescritos. Este estudo representa a primeira contribuição sobre o conhecimento de imaturos de espécies de Gyrinidae no Brasil, incrementando o conhecimento sobre a diversidade de espécies dessa família na Amazônia Central, além de fornecer caracterização morfológica detalhada sobre as espécies amostradas na área estudo facilitando a identificação das mesmas.

No description available.

INTRODUCTION:Whirligig beetles (Coleoptera: Gyrinidae) are aquatic insects living on the water surface. They are equipped with four compound eyes, an upper pair viewing above the water surface and a lower submerged pair viewing beneath the water surface, but little is known about how their visual brain centers (optic lobes) are organized to serve such unusual eyes. We show here, for the first time, the peculiar optic lobe organization of the larval and adult whirligig beetle Dineutus sublineatus.RESULTS:The divided compound eyes of adult whirligig beetles supply optic lobes that are split into two halves, an upper half and lower half, comprising an upper and lower lamina, an upper and lower medulla and a bilobed partially split lobula. However, the lobula plate, a neuropil that in flies is known to be involved in mediating stabilized flight, exists only in conjunction with the lower lobe of the lobula. We show that, as in another group of predatory beetle larvae, in the whirligig beetle the aquatic larva precociously develops a lobula plate equipped with wide-field neurons. It is supplied by three larval laminas serving the three dorsal larval stemmata, which are adjacent to the developing upper compound eye.CONCLUSIONS:In adult whirligig beetles, dual optic neuropils serve the upper aerial eyes and the lower subaquatic eyes. The exception is the lobula plate. A lobula plate develops precociously in the larva where it is supplied by inputs from three larval stemmata that have a frontal-upper field of view, in which contrasting objects such as prey items trigger a body lunge and mandibular grasp. This precocious lobula plate is lost during pupal metamorphosis, whereas another lobula plate develops normally during metamorphosis and in the adult is associated with the lower eye. The different roles of the upper and lower lobula plates in supporting, respectively, larval predation and adult optokinetic balance are discussed. Precocious development of the upper lobula plate represents convergent evolution of an ambush hunting lifestyle, as exemplified by the terrestrial larvae of tiger beetles (Cicindelinae), in which activation of neurons in their precocious lobula plates, each serving two large larval stemmata, releases reflex body extension and mandibular grasp.

Whirligig beetles are gregarious aquatic insects living on the water surface. They are equipped with two separate pairs of compound eyes, an upper aerial pair and a lower aquatic pair, but little is known about how their brains are organized to serve such an unusual arrangement. In the first study of this dissertation, I describe the neural organization of their primary visual centers (the optic lobes) of the larval and adult whirligig beetle Dineutus sublineatus. I show that the divided compound eyes of adult beetles supply elaborate optic lobes in the brain that are also split into an upper and a lower half, each optic lobe comprising an upper and lower lamina, an upper and lower medulla, and a partly split bilobed lobula. The exception is the fourth neuropil, the lobula plate. Studies of their development show that the lobula plate Anlagen serving the upper and lower eyes develop at different rates and thus different developmental stages. The upper lobula plate develops precociously in the larva and is thought to process information that enables subaquatic ambush hunting. During metamorphosis the upper lobula plate degenerates and is lost as are the larval stemmatal eyes supplying it. The lower lobula plate develops later, during metamorphosis, and is present in the imago where it is supplied by the lower compound retina. By analogy with dipteran lobula plates it is proposed to support subaquatic locomotory balance. In the subsequent study, I describe the neural organization of the whirligig beetle’s mushroom bodies, a pair of prominent brain centers in the forebrain that are best known for their roles in higher olfactory processing and olfactory-based learning and memory. I found that unlike other insects examined so far, the calyces of the whirligig beetle’s mushroom bodies are exclusively supplied by visual neurons from optic lobe neuropils serving the pair of upper aerial compound eyes, thereby showing a complete modality switch from olfaction to vision in this brain center. These findings, along with multiple evidence from hymenopteran insects and cockroaches, suggest that insect mushroom bodies are not merely olfactory-related but may be involved in visual tasks, such as memory of place. In the last study, I describe experiments to demonstrate that a group of D. sublineatus is able to learn their location with respect to visual cues provided from above the water line, and simultaneously establish and maintain their relative positions with each other within the group. These results provide an explanation as to how a collective, such as several hundred whirligig beetles, can maintain cohesion and remember landmarks that "anchor" the collective at a particular location in a pond or stream. Using techniques in comparative neuroanatomy, this dissertation documents visual specializations of an insect brain that has evolved to suit a unique group-living lifestyle on the water surface. In addition, the spatial learning paradigm described in the third study provides an essential assay for future lesion studies to determine if mushroom bodies are indeed required for visually mediated spatial learning and memory.

L’interface air-eau est un milieu où la tension de surface intervient en permanence pour minimiser l’énergie de la surface. Cette force est à l’origine des phénomènes capillaires que les organismes semi-aquatiques exploitent. L’objectif de cette thèse est d’étudier l’importance de ces phénomènes dans l’écologie des organismes semi-aquatiques en prenant les gyrins comme modèle. Les résultats montrent que le ménisque bipolaire produit par les gyrins est responsable d’auto-assemblables statiques entre individus immobiles. Les gyrins utilisent également différents types de nage pour minimiser les forces de résistance qu’ils rencontrent, notamment la force liée à la production d’onde. L’étude expérimentale de la perception d’objets immobiles suggère la perception des ménisques par les gyrins. L’écholocation grâce aux ondes de surface, supposée dans la littérature, ne peut cependant être exclue. / The surface tension at the air-water interface is responsible for capillary phenomena minimizing surface energies. Semi-aquatic organisms have evolved to exploit this capillarity. The purpose of this thesis is to study the importance of capillary phenomena in the ecology of semi-aquatic organisms using whirligig beetles as a model. Results show that the bipolar meniscus produced around whirligig beetles is responsible for static self-assembly between individuals. These insects use different types of swimming to minimize resistance forces, especially the wave drag. The experimental study of the detection of immobile objects suggests that whirligig beetles perceive the menisci. Echolocation using surface waves, assumed in literature, cannot however be excluded.