Insights on pollen diversity of honeybee Apis mellifera L. colonies located in various agricultural landscapes

Authors: ALBURAKI, MOHAMED - University Of Tennessee; GREGORC, ALES - Mississippi State University; Adamczyk, John; STEWART, SCOTT - University Of Tennessee

Submitted to: Southwestern Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2018
Publication Date: 3/20/2018
Citation: Alburaki, M., Gregorc, A., Adamczyk Jr, J.J., Stewart, S.D. 2018. Insights on pollen diversity of honeybee Apis mellifera L. colonies located in various agricultural landscapes. Southwestern Naturalist. 63/49-58. https://doi.org/10.1894/0038-4909.63.49.
DOI: https://doi.org/10.1894/0038-4909.63.49

Interpretive Summary: In an effort to identify landscapes that provide honeybee with the most sustainable pollen sources, we conducted a study in 2015 on pollen collected from honeybee hives located in various agricultural landscapes. Available pollen source, honeybee preferences and potential exposure to pesticides also were investigated. Sixteen honeybee colonies were located in four different landscapes; high (HighAG) and moderate agricultural (ModAG) areas, low agricultural (LowAG) area with high urban activity and a non-agricultural (NonAG) location. Pollen samples of those four landscapes were identified, and comprehensive pesticide residue analyses were carried out on representative set of samples. Our results indicate that LowAG area with urban activity had significantly higher pollen diversity than other locations with the least fluctuations across the season. The lowest pollen diversity was recorded in both the HighAG and NonAG areas (23 pollen types), suggesting that both settings lack many plant species attractive to bees. Non-crop pollen largely exceeded in number and amount the crop pollen collected, indicating that bees rely for their pollen-diet on a large spectrum of non-crop flowers. Besides that, none of the pesticides residue identified in the pollen samples were acutely harmful to the bees. Most importantly, further analyses showed no similar pattern in the sort of pollen collected by colonies of the same location, which indicates complexity and unpredictability in honeybee behavior regarding pollen preference and collection in the field.

Technical Abstract: In an effort to identify landscapes that provide honeybee Apis mellifera L. colonies with the most sustainable pollen sources, we conducted an extensive palynological analysis on trapped-pollen collected from honeybee hives located in various agricultural landscapes. Available pollen source, honeybee preferences and potential exposure to pesticides through crop pollen were investigated. A total of 128 trapped-pollen samples were collected throughout the 2015 season from sixteen honeybee colonies distributed in four different landscapes; high (HighAG) and moderate agricultural (ModAG) areas, low agricultural (LowAG) area with high urban activity and a non-agricultural (NonAG) location. Pollen samples of those four landscapes were identified, and comprehensive pesticide residue analyses were carried out on representative set of samples. Our results indicate that LowAG area with urban activity had significantly higher pollen diversity (31 pollen types) than other locations with the least fluctuations across the season. The lowest pollen diversity was recorded in both the HighAG and NonAG areas (23 pollen types), suggesting that both settings lack many plant species attractive to bees. Non-crop pollen largely exceeded in number and amount the crop pollen collected, indicating that bees rely for their pollen-diet on a large spectrum of non-crop flowers. Besides that, none of the pesticides residue identified in the pollen samples approached the honeybee LD50 concentrations. Most importantly, the PCA analyses showed no similar pattern in the sort of pollen collected by colonies of the same location, which indicates complexity and unpredictability in honeybee behavior regarding pollen preference and collection in the field.