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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Efeito de vespas galhadoras (Hymenoptera: Chalcidoidea) na duração da receptividade floral de Ficus citrifolia (Moraceae) / Galler wasps (Hymenoptera, Chalcidoidea) effect on th length of floral receptivity of Ficus citrifolia (Moraceae)

Silva, Pâmela Costa Adorno da 18 December 2009 (has links)
O sucesso reprodutivo das figueiras, e a consequente manutenção do mutualismo Ficus vespas de figo, depende do sucesso na polinização das flores pistiladas (produção de frutos) e do desenvolvimento de vespas polinizadoras em alguns ovários galhados (produção de vespas vetoras de pólen). No entanto, o período de receptividade das flores pistiladas para a polinização e oviposição pelas vespas polinizadoras de Ficus é curta, em relação à duração total do desenvolvimento do figo. A pequena janela temporal de receptividade pode ser um fator limitante na estabilidade do mutualismo, uma vez que o sucesso reprodutivo da planta será nulo se os figos não forem visitados por vespas polinizadoras durante o período de receptividade. O presente trabalho avaliou o papel das vespas não-polinizadoras galhadoras (Idarnes grupo flavicollis) durante o período de polinização Ficus citrifolia. Especificamente avaliou-se se as vespas galhadoras interferem (1) na atratividade do figo às vespas polinizadoras, (2) na receptividade do estigma e (3) no sucesso das vespas polinizadoras (produção de frutos e prole de vespas polinizadoras). O estudo experimental foi realizado no campus da USP Ribeirão Preto (21°10S; 47°48W), durante os meses de 02/2008 e 07/2009. Foi observado que os períodos de receptividade do estigma e de atratividade do figo duraram cerca de uma semana e não sofreram efeito da presença das vespas galhadoras. No entanto, o sucesso reprodutivo da planta foi afetado em situações de alta infestação das vespas não-polinizadoras, devido ao fechamento precoce do ostíolo causado pelo crescimento das galhas dessas vespas / The breeding success of Ficus trees and the maintenance of their mutualistic fig wasps depend on the successful pollination of pistilate flowers (seed production) and on the development of pollinating wasps in some galled ovaries (production of pollen vectors). The period during which pistilate flowers are receptive for pollination and oviposition is short compared to the total length of fig development. This narrow temporal window may be limiting to the stability of the mutualism, since the reproductive success of the plant will be null if wasps fail to find receptive trees. We investigated the role of the non-pollinating galler wasps (Idarnes group flavicollis) on the pollination period of Ficus citrifolia figs. Specifically, we tested if galler wasps interfere on (1) fig attraction for pollinating fig wasps, (2) length of stigma receptivity and (3) pollinating success (seed and pollinator offspring production). The study was carried out at the campus of University of São Paulo in Ribeirão Preto (21° 10\' S, 47° 48\' W) between february/2008 and march/2009. The periods of stigma receptivity and fig attractiveness lasted about one week and were not affected by the presence of galling non-pollinating fig wasps. However, the early ostiole closure caused by the growth of non-pollinating wasps galls may affect the plant reproductive success in high levels of infestation by these wasps
12

Interactions between figs (Ficus spp., Moraceae) and fig wasps (Chalcidoidea, Agaonidae)

Ware, Anthony Brian January 1993 (has links)
Fig trees (Ficus spp., Moraceae) and fig wasps (Chalcidoidea, Agaonidae) are uniquely associated. In one fig wasp group, the pollinators (Agaoninae), each species is generally host species-specific. The relationship is one of obligate mutualism where the wasps provide pollination services and in return utilises some of the ovules for larval development. Non-pollinating fig wasps (generally belonging to subfamilies other than the Agaoninae) may be gallers or parasitoids, and can also be host species-specific. In the accompanying studies we examined the factors governing the interactions between fig wasps and their host trees. Surveys of fig trees and their associated pollinating fig wasps conducted in southern Africa, Madagascar and The Comores generally confirmed their specific relationships. An examination of F. sycomorlls in Madagascar resulted in the reclassification of F. sakalavarum as a distinct species with its own specific pollinator species. Biological and chemical evidence is presented demonstrating that the pollinators were able to distinguish their hosts through volatiles which emanated from the figs when they were ready to be pollinated. Environmental factors were found to influence wasp behaviour. Ambient temperature governed the timing of wasp emergence from their natal figs. When dispersing from their natal figs, the fig wasps flew upwards and then were blown downwind. Once nearing trees bearing figs ready to be pollinated, the wasps lost height and flew upwind towards the trees. E. baijnathi females apparently avoided figs which already contained a conspecific foundress. Scanning electron microscope studies of pollinating female fig wasp antennae showed that while all the species possessed multiporous plate sensilla, in only a few species were these sensilla elongated. Multiporous plate sensilla elongation is rare or absent among other female chalcids and may have evolved within the Agaoninae in order to facilitate their location on receptive host figs. Pollinator choice specificity appears to break down in a number of cases. In the first case examined, two pollinator species were recorded from the figs of African F. sycomorus. One. C. arabicus, pollinates the figs while the other, C. galili, acts as a 'cuckoo' by utilising some of ovules for oviposition without providing pollen. In the second case three pollinating fig wasp species were recorded from the rigs of F. lutea. Two were found to be incidental visitors and were not specifically attracted to the tree. The hybrid seeds from these crosses were successfully germinated but the seedlings did not grow passed the cotyledon stage of their development. In the concluding study the consequences of Ficus phenology and the structure of the fig's unusual inflorescence on the nonpollinating fig wasp community were examined. Various factors affecting the population levels and species richness were also examined. Future possible research directions were discussed.

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