This study assesses the impacts of the invasive oil-collecting bee Centris nitida on the established endemic mutualism between Byrsonima lucida and Centris errans its sole native pollinator. In natural pine rocklands and urban areas, I examined the breeding system of B. lucida, assessed the degree of its pollen limitations, and compared the key processes of pollination for the Centris bees. Breeding system results showed that B. lucida was self incompatible and pollinator dependent. Pollen limitation treatments suggested that B. lucida is pollen limited, regardless of the contributions of the invasive bee. The native bee had significantly higher visitation rates to B. lucida plants, but had a lower foraging rate and was the less efficient pollinator. The invasive bee appears to be more common in urban environments. Further understanding the nature of these novel relationships is vital for the conservation of B. lucida and integrity of pine rocklands.

Most studies of foraging behavior in bees have been performed under artificial conditions. One highly neglected area is the daily nectar secretion rhythm in flowers including how nectar properties may vary with time of day. As a first step in understanding the connections between forager behavior and nectar presentation under more natural conditions, we examined nectar secretion patterns in flowers of the squash Cucurbita pepo. Under greenhouse conditions, squash flowers exhibit consistent diel changes in nectar volume and concentration through anthesis. These temporal patterns are robust, persisting under field conditions as well as simulated drought conditions in the greenhouse. In the presence of active pollinators, diel patterns are evident but with highly variable, severely reduced volumes. The potential consequences of these factors for pollinator behavior are discussed.

As urbanization increases globally, habitat loss is increasing at an unprecedented rate, eroding the suitability of many landscapes for most forms of wildlife, including bees. At least some of this habitat loss is through the ongoing expansion of urban areas, a process termed ‘urbanization’. Studies of the effects of urbanization and urban land use on bees have reported a mixture of results, including some instances where at least some species appear to do better in urban areas than they do in lands surrounding urban areas. While the impacts of urbanization on bee communities has been investigated, tree canopy cover has been largely overlooked as a contributor to urban bee distributions, despite their potential importance as a predictor of bee activity. I investigated the impacts of urban land use and tree canopy cover on bee communities across a variety of neighbourhoods in a medium-sized Canadian city (Ottawa, Ontario). In total, I surveyed bee communities in 27 residential yards that varied in terms of the degree of urban land use (measured as percent impervious surface area) and tree canopy cover (percent deciduous canopy cover) across a range of spatial scales. Using linear regression and model selection, I determined that bee abundance was negatively correlated with the degree of urban land use surrounding a yard, and positively correlated with the richness of the local (i.e., yard) flowering plant community. Yard floral richness, but not urban land use or tree cover, was also a predictor of the diversity of the bee community visiting the yard. In fact, tree canopy cover did not factor in any of the top models predicting either bee abundance, richness, or diversity. My results support the idea that urban land use could negatively impact bee communities, but also suggest that landscaping and urban planning decisions that maximize local floral richness could counteract some of the negative impacts of urbanization on bee populations.

No description available.

The superfamily Apoidea (commonly referred to as bees), are insects whose diet consists of the nectar and pollen from flowering plants. Therefore, they are essential pollinators of many species, both wild and cultivated. Bees are similar to other Hymenoptera in appearance, size, and color variety. The superfamily Apoidea contains 17,000 known species and could possibly contain up to 30,000. Bees perform many tasks that benefit humanity such as pollinating the flowers of both wild and cultivated plants. Without this work, fruits and seeds necessary for the survival of different species, for our own food supply, and for industry would not be able to be produced. The study was done in three communities in the Yungas (Carmen Pampa, San Pablo, and San Juan de la Miel). In each community, three Malaise traps were introduced in three ecological ni ches (Forest, Forest Edge, and Crop Area). Each collection was done every 14 days throughout the six months of winter and spring. The quantification and identification of the Apoidea was conducted in a laboratory through identification keys for families, genera, and species. In total, 83 different morphospecies were identified. In the three communities, a total of 1117 individuals were recorded during the six months of field work. With regard to the niche factor, Partamona sp. (sp2) and Apis mellifera (sp1) were those species that contributed most to the abundance of individuals. In addition, both species contributed to the similarity and dissimilarity seen in the three ecological niches of the three communities. This indicates that they are the most abundant groups within the Yungas forests. They nest primarily in wood, are highly general, are highly social, and are present throughout the year. It is also worth mentioning that the community and station factors do not contribute to the differences in species diversity. Based on the results of this research, a new phase was initiated to identify the species contained within the 83 morphospecies found in the Yungas of La Paz.

No description available.

This research presents the results of a bee survey (Hymenoptera: Apoidea) in remnants of the Mississippi Black Belt Prairie, a unique physiographical region that is a threatened community covering 14,141 square kilometers in both Mississippi and Alabama. Sampling was performed with sweep nets and Malaise traps. A total of 151 visits were made to several prairie remnant areas during the years 1999 – 2001 with 92 Malaise trap samples. Historical bee collection data from these prairies were incorporated into this survey. A total of 6,140 specimens resulting in 107 species, 51 new state records and eight disjunct species were collected within five bee families: Colletidae, Andrenidae, Halictidae, Megachilidae and Apidae. The most abundant species belonged to the Halictidae. The most common floral families visited were Asteraceae and Fabaceae. The addition of the species in this survey brings the state list of bees to at least 204.

No description available.

The sublethal dosage effects of carbaryl were studied in honey bee (Apis mellifera L.) colonies. Carbaryl was fed to colonies during a 14-day period in a 0.95 M sucrose solution. Carbaryl dosages were based on 0.0036, 0.0178, and 0.0356 ug/bee/day, and concentrations approximated 0.09, 0.44, and 0.86 ppm, respectively. Five potential areas of sublethal effect were examined: brood production, brood mortality, adult mortality, colony weight change, and worker resistance to the toxicant. The carbaryl dosages appeared to fall within the sublethal range. No significant differences (P≤0.05) in adult mortality were found between Control and carbaryl treatments during or following carbaryl application. Statistically-significant increases in brood production and brood mortality were observed at the median dosage, but no significant differences were found at the highest dosage. The lowest dosage also caused no significant differences in brood production. A significant increase in worker resistance to carbaryl was observed at the median dosage, but a significant decrease occurred at the highest dosage and the Control. No significant differences in colony weight change were observed during the treatment or post-treatment periods at any dosage. Although statistically-significant differences were observed, they were not felt to be biologically significant. Intra-treatment colony variation was considered to be partly responsible for the differences observed. This variation is great enough to make honey bee colonies unsuitable for general insecticide screening, although they may be useful when prior evidence of sublethal effects exists / Master of Science

No description available.