Abstract: Please read the abstract in the section 00front of this document
Abstract: Please read the abstract in the section 00front of this document
Abstract: Please read the abstract before the references of this document.
Abstract: Investigating the extent of local scale heterogeneity in assemblages is necessary to achieve a sound understanding of the processes giving rise to local assemblage patterns and the variation between them. Moreover, a clear understanding of local scale heterogeneity of assemblages is imperative in the development of effective regional conservation strategies. Previous studies examined the local scale heterogeneity in dung beetle assemblages between mixed woodland and sand forest hab...
Abstract: I studied the spatial distribution of South African avian species richness from the viewpoint that humans are a substantial modifying force on earth, and have also modified the historical spatial distribution of species richness. The main aim of the thesis is to investigate the way in which humans have modified avian species richness patterns in South Africa at the quarter-degree square (QDS) resolution, which is a phenomenon that has been either overlooked, or not completely clari...
Abstract: The Important Bird Areas (IBAs) network of BirdLife International aims to identify sites that are essential for the long-term conservation of the world’s avifauna. A number of global change events have the potential to negatively affect, either directly or indirectly, most bird species, biodiversity in general and associated ecological processes in these areas identified as IBAs. To assist conservation decisions, I assessed a suite of ten landscape scale anthropogenic pressures t...
Abstract: When provided with the opportunity to select their diet, most insect herbivores regulate their nutrient intake. However, in a nutritionally heterogeneous environment and with changing demands for growth, development and reproduction, obtaining the required amount and balance of nutrients is a challenge. This is especially true for social insects where the workers bring food into the colony to be shared by nestmates. The ability of insects to self-select their diet is an important t...
Abstract: Please read the abstract in the front section of this document
Abstract: Please read the abstract in the section, 00front of this document
Abstract: Pollination is an essential ecosystem service, increasing reproductive success of many crops, which can be provided by managed pollinators, wild bees (including honeybees) and other insect pollinators. However, the pollination services and the economic value of wild pollinators are often underestimated. Better understanding of the factors that influence honeybee foraging behaviour and pollination efficiency can contribute to the improvement of management practices that aim to enhan...
Abstract: One of the benefits of colonial living in insect societies is the ability to build a nest which enables the maintenance of a homeostatic microenvironment. The detrimental and uncertain effects of fluctuating ambient conditions are thus avoided. An extensive amount of work has documented the regulation of respiratory gases and temperature by honeybee (Apis mellifera) colonies but relatively little is known of their water relations. Nest humidity influences the fitness of the honeybe...
Abstract: Please read the abstract in the section 00front of this document
Abstract: Please read the abstract (Summary) in the section, 09summary and aknowledgements, of this document
Abstract: Fluid secretion by insect Malpighian tubules is controlled by haemolymph-bome factors. Two corticotropin-releasing-factor (CRF)-related diuretic peptides, Tenmo¬DH37 and Tenmo-DH47. previously isolated from Tenebrio molitor, were found to stimulate in vitro tubule preparations of Tenebrio molitor via the second messenger cyclic AMP. The stimulatory effect of Tenmo-DH37 was reversed on addition of endogenous antidiuretic peptides (Tenmo-ADFa and ADFb) and exogenous cardioaccelerato...
Abstract: Please read the abstract in the section 00front of this document