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Wolbachia are maternally inherited, obligate, intracellular bacteria inducing a form of sterility known as cytoplasmic incompatibility. Wolbachia based strategies have been proposed for the control of disease vectors. One example is to use a population replacement strategy to drive into natural population a novel Wolbachia that modifies the age structure of a vector population, reducing disease transmission. In this research, the effects of a life-shortening stain of Wolbachia (popcorn Wolbachia) are transferred into the mosquitoes Aedes albopictus (Chapter Two and Three) and A. aegypti (Chapter Four and Five). In Chapter Two, the Wolbachia symbiosis significantly reduced fecundity and egg hatches in A. albopictus, with Wolbachia being highly pathogenic in this mosquito species. In Chapter Three, the relationship between popcorn Wolbachia and its host (in a triple-infected mosquito strain) varied with the mosquito diet. Feeding on mouse blood was associated with the loss of infection, whereas the infection was maintained in human blood-fed mosquito lines. Egg viability of triple infected mosquito was reduced only with mouse blood. In Chapter Four, the reduced competitiveness (e.g., low survival and increased developmental time) of infected A. aegypti immatures was associated with popcorn Wolbachia, relative to uninfected individuals in low food condition. In Chapter Five, the decreased survival of immature A. aegypti was associated with popcorn Wolbachia in the presence of potential predators (i.e., older A. aegypti or A. albopictus larvae). Using a novel behavioral assay, a delayed larval reaction to light avoidance was observed to be associated with the infection, suggesting Wolbachia effects on immature host behaviors. In Chapter Six, popcorn Wolbachia and wAlbB infected A. aegypti showed similar reproduction potential. No reduced level of CI or mating competitiveness was observed in wAlbB infected males. The results suggest the wAlbB infection in A. aegypti can be an additional agent for Wolbachia-based control strategies. In Chapter Seven, a filtering system using commercially available sieves was able to separate immature mosquitoes from water, preventing escape of mosquitoes. In Chapter Eight, an inexpensive artificial blood feeding was designed for feeding multiple mosquito cages. The results support the use of these tools to facilitate mass rearing of mosquitoes.

Body size is a universal property affecting biological structure and function, from cell metabolism to animal behavior. The nervous system, the physical generator of behavior, is also affected by variations in body size; hence potentially affecting the way animals perceive, interpret and react to the environment. When animals join to form groups, such individual differences become part of the structure of the society, even determining social roles. Here, I explore the association between body size, behavior and social organization in honeybees and bumblebees. Focusing on bumblebees, I explore the link between body size, brain allometry and learning and memory performance, within the context of task specialization. I show that body size goes along with brain size and with learning and memory performance, and that foraging experience affects such cognitive and neural features. Next, I explore the association between body size and foraging task specialization in honeybees. Previous evidence showed a link between specialization on pollen or nectar foraging and sensory sensitivity, further associating sensitivity to the quality and/or quantity of resource exploited. I hypothesize that, as in solitary bees, larger body size is associated with higher sensory sensitivity. I test this hypothesis by comparing body size and the quality and quantity of the resource exploited by wild Africanized and European honeybees. I show that nectar foragers are smaller and have fewer olfactory sensilla, which might underlie their lower sensitivity to odors. Also, larger bees collect more pollen (within pollen foragers) and more dilute nectar (within nectar foragers). To further test this `size hypothesis', I compare strains of bees selected to store large ("high strain") or small ("low strain") amounts of pollen surplus. As these strains differ in sensory sensitivity, I predict that the more sensitive high strain bees are larger and have more sensory sensilla. I show that high strain bees are generally bigger, but have fewer sensory sensilla than low strain bees. These results show that in bees, body size is associated with an individual's sensory, neural and cognitive features, further suggesting that body size plays a more important role in the organization of bee societies than generally assumed.

Symbiosis is one of the main players in evolution and ecology of organisms. Such intimate interactions may be diverse and have a great impact in biological diversification. One of the main associations that occur in nature is that of insects and microbes. Insect associated microbes are, capable of altering a wide range of physiological, behavioral, ecological and evolutionary events for their hosts. Two very common insect microbial symbionts are Wolbachia and Spiroplasma. Wolbachia is also common to other arthropods and nematodes. To better understand how these relations could influence the behavior of insects, we selected two biological systems to investigate how these symbionts can interfere in the host - parasitoid interactions. We investigated the behavior of two species of parasitoids, Aphelinus asychis (Hymenoptera: Aphididae) and Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) when exploting patches with their respective hosts, Aphis citricidus (Hemiptera: Aphididae) and Anagasta kuehniella (Lepidoptera: Pyralidae). In the first case we looked into how Spiroplasma infecting hosts, and in the second case how Wolbachia infecting the parasitoid may affect parasitoid patch exploitation. We recorded the wasp\'s behaviors when exploiting their patches, as well as the aphid defensive behavior in response to parasitoid attack. Our data demonstrate Spiroplasma and Wolbachia influence the parasitoid patch exploitation decisions. Spiroplasma also affected the defense behavior and aggressiveness of A. citricidus in response to A. asychis attack. Wolbachia increased the patch residence time and reduced the successful parasitization of host eggs in T. pretiosum. The understanding of such effects will certainly contribute to provide a better knowledge of the outcome of the associations of insects with microbial symbionts, providing ground base for the proper exploitation of such interactions for biological control purposes. / A simbiose é um dos principais agentes na evolução e ecologia de organismos. Tais interações são muito íntimas, podendo ser muito diversas e ter grandes impactos na diversidade biológica. Uma das principais associações que ocorrem na natureza é aquela entre insetos e microrganismos. Microrganismos associados a insetos são capazes de alterar uma gama de eventos fisiológicos, comportamentais, ecológicos e evolutivos em seus hospedeiros. Dois simbiontes de insetos muito comuns são Wolbachia e Spiroplasma. Wolbachia é também muito comum a outros artrópodes e nematoides. Para melhor compreender como essas relações podem influenciar o comportamento de insetos, dois sistemas biológicos foram selecionados para investigar como esses simbiontes podem interferir nas interações hospedeiro-parasitoide. O comportamento de duas espécies de parasitoides, Aphelinus asychis (Hymenoptera: Aphididae) e Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) foi investigado quando explorando patches com seus respectivos hospedeiros, Aphis citricidus (Hemiptera: Aphididae) e Anagasta kuehniella (Lepidoptera: Pyralidae). No primeiro caso foi investigado como a infecção do hospedeiro por Spiroplasma, e no segundo caso como a infecção do parasitoide por Wolbachia, afetariam a exploração da patch pelos parasitoides. O comportamento dos parasitoides ao explorarem suas patches foi registrado, assim como os comportamentos de defesa dos pulgões em resposta ao ataque do parasitoide. Os dados obtidos demonstraram que Spiroplasma afetaram o comportamento de defesa e a agressividade de A. citricidus em resposta aos ataques de A. asychis. Wolbachia aumentou o tempo de residência e reduziu o sucesso de parasitismo de ovos do hospedeiro por T. pretiosum. A compreensão de tais efeitos certamente contribuirá para o melhor entendimento dos efeitos da associação de insetos a simbiontes, fornecendo bases sólidas para a melhor exploração de tais interações para propósitos de controle biológico de pragas.

A traça das crucíferas, Plutella xylostella (L.) (Lepidoptera: Plutellidae), é uma das pragas mais importantes de Brassicaceae no Brasil e no mundo, causando sérios danos em repolho, couve-flor e couve comum, entre outras. O objetivo desta pesquisa foi estudar os parâmetros populacionais e a resposta comportamental de P. xylostella criada por dezoito gerações, utilizando três variedades: Brassica oleracea var. acephala couve manteiga hibrida HS-20, B. oleracea var. italica couve brócolis Piracicaba e B. oleracea var. capitata repolho Bob Cat. Para condução dos experimentos foram separados três lotes de pupas de P. xylostella da criação mantida no laboratório, no qual foram utilizadas apenas folhas de couve para sua manutenção. Cada lote foi mantido em substrato diferente, ou seja, a criação inicial foi dividia em três populações tendo como variável o substrato alimentar e de oviposição utilizado na criação (couve, brócolis ou repolho). Com os dados biológicos de P. xylostella foram estimados os parâmetros populacionais de tabela de vida de fertilidade a cada três gerações, comparando-se as cultivares testadas em relação ao desenvolvimento, sobrevivência e reprodução da praga. Além disso, lotes de insetos oriundos de cada substrato de criação foram separados a cada três gerações para realização de testes de dupla e múltipla chance de escolha (preferência para alimentação e oviposição). Os parâmetros populacionais de P. xylostella indicam que as brassicáceas testadas permitem o crescimento populacional do inseto nos respectivos hospedeiros. O comportamento de seleção hospedeira na fase pré-imaginal e imaginal de P. xylostella não é afetado pela experiência alimentar e de oviposição nos substratos testados até a geração F18. / The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is one of the most important pests of Brassicaceae in Brazil and worldwide, causing serious damage to cabbage, cauliflower and kale common, among others. The aim of this research was to study the population parameters and the behavioral response of P. xylostella reared for eighteen generations, using three varieties: Brassica oleracea var. acephala - cabbage hybridizes HS-20, B. oleracea var. italica - Piracicaba broccoli and B. oleracea var. capitata - cabbage Bob Cat. To conduct the experiments were separate three batches of DBM from pupae held in the laboratory setting, in which only kale leaves were used for maintenance. Each batch was kept at different substrate, namely the initial rearing was divided into three populations having as variable the feeding and oviposition substrate used in rearing (kale, broccoli, and cabbage). With biological data of P. xylostella were estimated the population parameters of fertility life table every three generations, comparing the tested cultivars in relation to the development, survival and reproduction of the pest. Moreover, lots of insects derived from each rearing substrate were separated every three generations for performing dual choice and multiple-choice tests (preference for feeding and oviposition). The population parameters of P. xylostella indicate that brassicas tested allow the insect population growth in their hosts. The host selection behavior in pre-imaginal and imaginal stage of P. xylostella is not affected by food and oviposition experience on substrates up to F18 generation.

Doctor of Philosophy / Department of Entomology / Brian P. McCornack / Timely enactment of insect pest management and incursion mitigation protocols requires development of time-sensitive monitoring approaches. Numerous passive monitoring methods exist (e.g., insect traps), which offer an efficient solution to monitoring for pests across large geographic regions. However, given the number of different monitoring tools, from specific (e.g., pheromone lures) to general (e.g., sticky cards), there is a need to develop protocols for deploying methods to effectively and efficiently monitor for a multitude of potential pests. The non-random movement of the Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae), toward several visual, chemical, and tactile cues, makes it a suitable study organism to examine new sensor technologies and deployment strategies that can be tailored for monitoring specific pests. Therefore, the objective was to understand Hessian fly behavior toward new sensor technologies (i.e., light emitting diodes (LEDs) and laser displays) to develop monitoring and deployment strategies. A series of laboratory experiments and trials were conducted to understand how the Hessian fly reacts to the technologies and how environmental factors may affect the insect’s response. Hessian fly pupae distribution within commercial wheat fields was also analyzed to determine deployment of monitoring strategies. Laboratory experiments demonstrated Hessian fly attraction to green spectrum (502 and 525 nm) light (LEDs), that response increased with light intensity (16 W/m2), and that they responded in the presence of wheat odor and the Hessian fly female sex-pheromone, but, response was reduced under ambient light. These laboratory experiments can be used to build a more targeted approach for Hessian fly monitoring by utilizing the appropriate light wavelength and intensity with pheromone and wheat odor to attract both sexes, and mitigating exposure to ambient light. Together this information suggested that light could be used with natural cues to increase attraction. Therefore, a light source (green laser display) was applied to a wheat microcosm, which resulted in greater oviposition in wheat covered by the laser display. Examination of Hessian fly pupal distribution within commercial wheat fields showed that proportion of wheat within a 1 km buffer of the field affected distribution between fields. This helps to inform deployment of monitoring strategies as it identified fields with a lower proportion of wheat within a 1 km buffer to be at higher risk Hessian fly infestation, and therefore monitoring efforts should be focused on those fields. Together this work demonstrates Hessian fly behavior toward new sensor technologies, how those technologies interact with environmental cues, and how environmental composition affects pupal distribution. Collectively this information will enable cheaper, more accurate and more efficient monitoring of this destructive pest.

A traça das crucíferas, Plutella xylostella (L.) (Lepidoptera: Plutellidae), é uma das pragas mais importantes de Brassicaceae no Brasil e no mundo, causando sérios danos em repolho, couve-flor e couve comum, entre outras. O objetivo desta pesquisa foi estudar os parâmetros populacionais e a resposta comportamental de P. xylostella criada por dezoito gerações, utilizando três variedades: Brassica oleracea var. acephala couve manteiga hibrida HS-20, B. oleracea var. italica couve brócolis Piracicaba e B. oleracea var. capitata repolho Bob Cat. Para condução dos experimentos foram separados três lotes de pupas de P. xylostella da criação mantida no laboratório, no qual foram utilizadas apenas folhas de couve para sua manutenção. Cada lote foi mantido em substrato diferente, ou seja, a criação inicial foi dividia em três populações tendo como variável o substrato alimentar e de oviposição utilizado na criação (couve, brócolis ou repolho). Com os dados biológicos de P. xylostella foram estimados os parâmetros populacionais de tabela de vida de fertilidade a cada três gerações, comparando-se as cultivares testadas em relação ao desenvolvimento, sobrevivência e reprodução da praga. Além disso, lotes de insetos oriundos de cada substrato de criação foram separados a cada três gerações para realização de testes de dupla e múltipla chance de escolha (preferência para alimentação e oviposição). Os parâmetros populacionais de P. xylostella indicam que as brassicáceas testadas permitem o crescimento populacional do inseto nos respectivos hospedeiros. O comportamento de seleção hospedeira na fase pré-imaginal e imaginal de P. xylostella não é afetado pela experiência alimentar e de oviposição nos substratos testados até a geração F18. / The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is one of the most important pests of Brassicaceae in Brazil and worldwide, causing serious damage to cabbage, cauliflower and kale common, among others. The aim of this research was to study the population parameters and the behavioral response of P. xylostella reared for eighteen generations, using three varieties: Brassica oleracea var. acephala - cabbage hybridizes HS-20, B. oleracea var. italica - Piracicaba broccoli and B. oleracea var. capitata - cabbage Bob Cat. To conduct the experiments were separate three batches of DBM from pupae held in the laboratory setting, in which only kale leaves were used for maintenance. Each batch was kept at different substrate, namely the initial rearing was divided into three populations having as variable the feeding and oviposition substrate used in rearing (kale, broccoli, and cabbage). With biological data of P. xylostella were estimated the population parameters of fertility life table every three generations, comparing the tested cultivars in relation to the development, survival and reproduction of the pest. Moreover, lots of insects derived from each rearing substrate were separated every three generations for performing dual choice and multiple-choice tests (preference for feeding and oviposition). The population parameters of P. xylostella indicate that brassicas tested allow the insect population growth in their hosts. The host selection behavior in pre-imaginal and imaginal stage of P. xylostella is not affected by food and oviposition experience on substrates up to F18 generation.

Acoustic communication, used by a wide variety of animals, consists of the signaler, the signal and the receiver. A change in the behaviour of the receiver after reception of the signal is a prerequisite for communication. A response to the signal by the receiver depends on signal recognition and localization of the signal source. These two aspects, namely recognition and localization by the receiver, form the main body of my work. In the mating system of crickets, the males produce advertisement calls to attract silent females to mate. Females need to recognize the conspecific call and localize the male. The tree cricket Oecanthus henryi, due to aspects of its physiology and the environment it inhabits, generates interesting problems concerning these seemingly simple tasks of recognition and localization. In crickets, usually a species-specific sender-receiver match for the call features exists, which aids in recognition. A change in the call carrier frequency with temperature, due to poikilothermy, as seen in O. henryi, may pose a problem for this sender-receiver match. To circumvent this, either the response should shift concomitantly with the change in the feature (narrow tuning) or the response should encompass the entire variation of the feature (broad tuning). I explored the response of O. henryi females to the changing nature of call carrier frequency with temperature. The results showed that O. henryi females are broadly tuned to call carrier frequency. Being broadly tuned I next wanted to explore if within the natural variation in carrier frequency, the females were able to discriminate between frequencies. Females were found not to discriminate between frequencies. Cricket ears being pressure difference receivers are inherently directional, however their directionality is dependent on frequency, which may be affected by the change in carrier frequency due to temperature. Thus I also tested the effect of frequency on the azimuthal localization accuracy. The azimuthal accuracy was not affected by call carrier frequency within the natural range of frequency variability of the species. In south India, O. henryi is found in sympatry with Oecanthus indicus. Reproductive isolation between the two is maintained through calls. Since O. henryi is broadly tuned to frequency, call carrier frequency is unlikely to enable differentiation between conspecific and heterospecific calls. I thus tested whether the temporal features can account for the same. I constructed a quantitative multivariate model of response space of O. henryi incorporating results from various playback experiments. The model predicted high responses for conspecific calls and low responses for heterospecific calls, indicating that temporal features could suffice to discriminate between the two species. The quantitative model could also be used more generally to check responses to other heterospecifics and to compare responses between conspecifics from different populations. O. henryi is found on a bush and thus the female has to navigate in a 3D environment to localize the singing male. Very few studies have explored 3D localization in insects and moreover an algorithm explaining the procedure is missing. I attempted to model the 3D localization capability in O. henryi. To understand the rules behind the localization animals were observed in the wild as well as on a 3D grid in the laboratory and simulations were created to capture the nature of the phonotaxis. Neither a random model nor a deterministic model (which estimated the shortest path) could predict the paths observed in the grid. A less complex Bayesian stochastic model performed better than a more complex one. From the assumptions of the model it was inferred that the animal, for 3D localization, basically performs localization in the azimuthal plane and combines certain simple rules to go up or down. This study has examined receiver tuning in response to change in carrier frequency with temperature, which to my knowledge had not been explored before for insects. In this study I also attempted to create a quantitative multivariate receiver response space through statistical modeling, a method that can be applied in similar studies across taxa in various acoustic communication systems. A detailed Bayesian algorithm to explain 3D localization for an insect was attempted which has also not been attempted before.

Made available in DSpace on 2015-03-26T13:30:52Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1185327 bytes, checksum: a982e01beb2959753a39f1f0d06ce4e2 (MD5) Previous issue date: 2014-10-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Insect hosts that have been already parasitized are considered a low quality resource, which may affect the number of ovipositions made by other parasitoids. Since the amount of eggs laid affects the host immune response, the offspring survivorship may also be affected. For this reason, it is necessary to understand to what point the energy spent in superparasitizing is an advantage that allows supression of host immune response and provides adequate resources for the imatures to develop within their host. This study had the objective of finding the number of ovipositions from Palmistichus elaeisis (Hymenoptera: Eulophidae) allowing optimal offspring fitness and to analyze if immune response the melonworm Diaphania hyalinata L. (Lepidoptera: Crambidae) is correlated with the density of posture by the parasitoid. Pupae of D. hyalinata received from one to five parasitoid ovipositions. The total number of offspring produced, the number of males and females emerging from the host, sex ratio, life cycle, average body mass and biomass produced per parasitized pupae were recorded for the different oviposition densities. Digital x-ray imaging of parasitized hosts were recorded to assessing the immature parasitoid developmental until adult emergence. Incidence of unviable parasitoid larvae was also recorded. The survivorship of P. elaeisis was daily assessed. Hemocyte dynamics and encapsulation capacity of D. hyalinata against P. elaeisis was evaluated for each number of ovipositions, from one to five. The Parasitoid developmental time decreased with increased oviposition density and three ovipositions provided higher offspring and particularly female production, and optimal larval fitness. Progeny body mass and sex ration were not affected by oviposition density. Female and male survived longer with one oviposition of the female parasitoid. Parasitoid emergence increased with the number of parasitoid ovipositions and 100% parasitism and corresponding 100% host pupa mortality were achieved with all oviposition densities. Increased number of ovipositions decreased the number of total hemocytes, and also of granulocytes, plasmatocytes and prohemocytes in the circulating host hemolymph. Oenocytes and espherulocytes were not affect by the number of parasitoid ovipositions in the host. The melanization and encapsulation rates decreased with the number of ovipositions by P. elaeisis. Three ovipositions by the parasitoid female allowed optimal progeny production and parasitoid performance. Superparasitism is a strategy of P. elaeisis for optimal progeny fitness balancing optimal progeny performance with amelioration of host immune response. / Hospedeiros parasitados são considerados de baixa qualidade e podem influenciar no número de oviposições de parasitoides, influenciando na sobrevivência da progênie, pois, a quantidade de ovos depositados afeta a resposta imune do hospedeiro. Por isso, torna-se necessário saber até quando o investimento de superparasitar é vantajoso ao ponto de suprimir a resposta imune do hospedeiro e favorecer uma ótima competição de imaturos dentro do hospedeiro. O objetivo desta pesquisa foi reconhecer a densidade ótima de posturas de Palmistichus elaeisis (Hymenoptera: Eulophidae) para produção de progênie, e saber se a resposta imune do hospedeiro Diaphania hyalinata L. (Lepidoptera: Crambidae) ao parasitismo se relaciona a esta densidade ótima. Pupas de D. hyalinata foram expostas a uma, duas, três, quatro e cinco posturas por uma mesma fêmea do parasitoide. O número total de progênies, de machos e fêmeas emergidos, razão sexual, ciclo de vida, peso médio e biomassa produzida foram analisados. A velocidade de pupação, tempo entre pupa e emergência de P. elaeisis e a porcentagem de pupas com imaturos inviáveis deste parasitoide foram observados em pupa de D. hyalinata em sistema de radiografia digital. A sobrevivência de adultos de P. elaeisis foi avaliada diariamente. A porcentagem de emergência da progênie foi avaliada. A dinâmica hemocitária e a capacidade de encapsulação por pupas de D. hyalinata contra P. elaeisis foi avaliada mediante o número de posturas. Larvas de P. elaeisis empuparam mais rápido e o tempo entre o período de pupa e a emergência foi praticamente constante com três oviposições, variando para os demais tratamentos. Três oviposições proporcionou o maior número de fêmeas, total de emergidos e desempenho e, menor tempo de desenvolvimento dos parasitoides. O peso da progênie e a razão sexual foram semelhantes entre os indivíduos. Fêmeas e machos de pupas com uma oviposição sobreviveram mais que os demais tratamentos. A porcentagem de emergência de parasitoides aumentou com o número de posturas. O parasitismo foi de 100% em todos os tratamentos. Pupas com quatro e cinco oviposições não tiveram larvas inviáveis. O aumento do número de posturas reduziu o número de hemócitos totais e de granulócitos, plasmatócitos e prohemócitos circulantes na hemolinfa de pupas de D. hyalinata. Oenocitóides e esferulócitos circulantes mostraram padrão aleatório entre os tratamentos. A taxa de encapsulamento e de melanização decresceram com o aumento de oviposições de P. elaeisis. A oviposição por três vezes maximizou a progênie, reduziu o tempo de desenvolvimento e aumentou o desempenho de P. elaeisis. O superparasitismo é uma estratatégia em P. elaeisis para o aumento de sobrevivência e desempenho da prole.

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