Koech, Sheila2025-04-042025-04-042024-09https://ir-library.ku.ac.ke/handle/123456789/29914A Research Thesis Submitted in Partial Fulfilment of the Requirements for the Award of the Degree of Master of Science (Plant Ecology) in the School of Pure and Applied Sciences of Kenyatta University, September 2024 Supervisor: 1.Rebecca Karanja 2.Michael LattorffHoneybees are eusocial insects which live in highly organized colonies. Honeybees forage on nectar and pollen from flowering plants. Corbicula pollen is the pollen found in the hind legs of honeybees. Honeybees exhibit a generalist behavior, making it relatively simple to discern a diverse array of flowering plants based on the pollen they gather. Understanding the role of landscapes and flowering seasons is essential for pollinator health, particularly in agricultural landscapes such as Murang’a (Kenya), where landscape exhibits significant fragmentation, with cultivated crops replacing the original natural vegetation. This study involved the assessment of both the quality and quantity of corbicula pollen and examining how they fluctuated across flowering seasons and landscapes. Sampling of honeybee-collected pollen from 18 apiaries occurred monthly over a period of 12 months, encompassing three distinct landscape types (low, medium and high) classified using the Normalized Difference Vegetation Index (NDVI). Floral origins were identified through palynological analysis, protein content quantified via spectrophotometric analysis, and the types and levels of pesticide residues were determined using QUECHERS method. Pollen Hazard Quotient (PHQ) was employed to assess the potential risk to honeybees posed by each identified pesticide. Results showed that plant families Lauraceae and Poaceae were the most abundant at 20.5%. The months of February, June and July exhibited the highest polled diversity. Pollen protein ranged between 0.01 - 7.11 % with the plant families Fabaceae, Lauraceae, and Solanaceae having the highest average amounts of crude protein (7.11, 6.87, & 6.66%, respectively). Cupressaceae and Rosaceae recorded lowest amounts (0.39 and 0.01, respectively). The month of November (2019), March, June and August-2020 recorded the highest amounts of protein respectively. 11 pesticide residues were detected with concentrations between 0.1 to 1203 µg kg-1. Two fungicides (Carbendazim and Trifloxystrobin) and nine insecticides (Acephate, Carbofuran, Chlorpyriphos, Imidacloprid, Spinosyn A and D, Thiamethoxam, Acetamiprid, and Indoxacarb) were detected. Insecticides (81.8%) were the most widely used, while fungicides (18.2%) were the least used. The pesticides were identified in 11 plant families, with Asteraceae and Poaceae being the most heavily contaminated, accounting for over 60% of the detected pesticides. The results suggest that honeybees collect pollen from a wide variety of flowers. Honeybee-collected pollen vary in terms of their diversity, abundance, crude protein content across the sampling time. Honeybee-collected pollen was also found to contain pesticide residues. while land use may not correlate with the quality or quantity of available pollen resources, the nutritional landscape of Murang’a is seasonally dynamic in terms of bee forage hence imposing seasonal resource limitations. There is a need to supplement domesticated bees with alternative non-contaminated pollen sources due to the seasonal resource limitations.enThesis