Collection and Identification of Pollen from Honey Bee Colonies

Abstract

Researchers often collect and analyze corbicular pollen from honey bees to identify the plant sources on which they forage for pollen or to estimate pesticide exposure of bees via pollen. Described herein is an effective pollen-trapping method for collecting corbicular pollen from honey bees returning to their hives. This collection method results in large quantities of corbicular pollen that can be used for research purposes.Honey bees collect pollen from many plant species, but typically visit one species during each collection trip. Therefore, each corbicular pollen pellet predominantly represents one plant species, and each pollen pellet can be described by color. This allows the sorting of samples of corbicular pollen by color to segregate plant sources.Researchers can further classify corbicular pollen by analyzing the morphology of acetolyzed pollen grains for taxonomic identification. These methods are commonly used in studies related to pollinators such as pollination efficiency, pollinator foraging dynamics, diet quality, and diversity. Detailed methodologies are presented for collecting corbicular pollen using pollen traps, sorting pollen by color, and acetolyzing pollen grains. Also presented are results pertaining to the frequency of pellet colors and taxa of corbicular pollen collected from honey bees in five different cropping systems.Pollen is the primary source of protein, lipids, vitamins, and minerals for bees and has been used in many agricultural and ecological studies to understand colony-level foraging preferences of honey bees, evaluate the impact of pollen

Floral resources used by bees in urban areas: the case of Geneva, Switzerland

“…In order to compare resources used by bees between urban and agricultural habitat, we sampled pollen load in 10 urban and 5 agricultural hives in the region of Geneva (Figure 1), using pollen traps (Topitzhofer et al, 2021). These traps were set off collecting pollen during 24 hours every second week, between May and October 2016, for a total of 11 sampling dates.…”

“…We also weighted approximately thirty pollen loads subsamples, where the exact number of loads were known, in order to assess the mean weight of a single pollen load, which enabled us to calculate the contribution of each plant group within the whole sample. Usually, domestic bees collect one plant species at a time (Percival, 1947;Louveaux, 1990;Topitzhofer et al, 2021) which enable us to make one microscopic preparation for each color of pollen load. Because several plant species can display very similar colors, we used three to five pollen loads among a color, for each microscopic preparation.…”

Pollinators limit seed production in an early blooming rare plant: evidence of a mismatch between plant phenology and pollinator emergence

“…When we observe a bee visiting a flower, that bee may be drinking nectar, collecting pollen or both. In order to understand which plants bees actively collect pollen at, the pollen loads on bees must be examined (Thorp 2000, Delaplane et al 2013, Topitzhofer et al 2021. Examining the pollen on pollinators collected in the vicinity of a specific plant is a valuable method of estimating which insects transport pollen (Bosch et al 2009) and provides additional information beyond visitation observations.…”