The impact of urbanization on nesting behaviors of native bee species

Thesis Abstract

Urbanization significantly alters natural habitats, impacting biodiversity and ecological processes, yet the specific effects on the nesting behaviors of native bee species remain insufficiently understood. This study investigates how varying degrees of urban development influence the nesting preferences, site selection, and reproductive success of native bees, with a focus on Apis mellifera, Bombus spp., and solitary bee species across peri-urban and urban settings within a metropolitan region. The primary aim is to elucidate the relationship between urban landscape features and bee nesting ecology, thereby contributing to sustainable urban biodiversity management. The research objectives include identifying key urban landscape variables affecting nesting sites, comparing nesting site selection patterns between urban and peri-urban populations, and assessing the reproductive outcomes associated with different nesting environments. Employing a comparative cross-sectional research design, the study integrates both qualitative and quantitative data collection methods. The population encompasses native bee colonies and nesting sites within three designated zones characterized by low, medium, and high urbanization levels. A stratified random sampling technique was employed to select 25 nesting sites per zone, totaling 75 sites. Data collection comprised field surveys using standardized netting and visual observation methods to document nesting behaviors and site characteristics, supported by geospatial mapping of landscape variables such as vegetation cover, availability of nesting substrates, and proximity to anthropogenic structures. Additionally, semi-structured interviews with environmental managers provided contextual insights. The reliability of data collection instruments was ensured through pilot testing and inter-observer calibration, while validity was supported by adherence to established ecological survey protocols. Data analysis incorporated descriptive statistics to profile nesting preferences across zones, followed by multivariate regression analysis to identify significant landscape predictors influencing nesting site selection. Structural Equation Modeling (SEM) was employed to explore causal relationships between urbanization factors and nesting behaviors. Reproductive success indicators, including brood counts and offspring viability, were analyzed using ANOVA to compare across different habitat types. The theoretical framework is grounded in the Ecological Niche Theory and the Habitat Selection Theory, which underpin the understanding of behavioral adaptations in changing environments. Anticipated findings suggest that increased urbanization correlates with altered nesting site availability, with native bees exhibiting adaptive nesting behaviors such as nesting in artificial structures or modified natural substrates, albeit with reduced reproductive success compared to less urbanized areas. The study expects to reveal significant landscape predictors—such as green space fragmentation, substrate diversity, and human disturbance—that influence nesting choices. These insights are envisaged to fill existing gaps in understanding the behavioral plasticity of native bees in urban contexts, contributing novel empirical evidence to the field of urban ecology and pollinator conservation. The study's contribution lies in advancing knowledge on how urbanization affects native bee nesting ecology and informing urban planning policies to support pollinator health. It recommends the integration of bee-friendly habitats into urban development projects, preservation of native nesting substrates, and community engagement in pollinator conservation efforts. The findings will serve as a basis for developing targeted strategies to mitigate the negative impacts of urbanization on native bee populations, thereby promoting resilient urban ecosystems and sustainable biodiversity practices.