Pollen Collection, Honey Production, and Pollination Services: Managing Honey Bees in an Agricultural Setting

Abstract

Hybrid canola seed production is an important pollination market in Canada; typically both honey bees (Apis mellifera L. (Hymenoptera: Apidae)) and Alfalfa Leafcutting bees (Megachile rotundata Fab. (Hymenoptera: Megachilidae)) are concurrently managed to ensure pollination in this high-value crop. Beekeepers are paid to provide pollination services, and the colonies also produce a honey crop from the canola. Pollen availability from male-fertile plants is carefully managed in this crop to provide an abundance of pollen to fertilize male-sterile ('female') plants. This abundance of pollen represents an underutilized resource for beekeepers, and an opportunity to diversify the hive-products produced for market in this management system. We used a commercial-style pollen trap to collect pollen from colonies twice weekly for the duration of canola pollination, and compared the honey production and amount of sealed brood in colonies with pollen traps to those without pollen traps. We found that while pollen trapping reduced honey production, there was no negative impact on brood production, and at current market prices, the per-hive revenue was higher in colonies from which pollen was trapped. Pollen trapping honey bee colonies in the context of hybrid canola pollination, therefore, offers beekeepers an opportunity to diversify their products and increase their revenue.

Keywords: honey bee management; honey production; pollen collection; pollen trapping; pollination.

Fig. 1.

The dot indicates the location of the study sites, three hybrid canola seed production fields near Lethbridge, Alberta, Canada (Nearctic-Ecozone Western Canada by CarolSpears is licensed under CC by-SA 3.0).

Fig. 2.

Photograph of a typical layout of a canola seed production field, showing honey bee colonies on the field edge, and leafcutting bee shelters (orange and green tents) within the crop. Visible are the wide bays containing male-sterile (female) plants, and the narrower, pollen-bearing male bays. Both male and female plants offer nectar as a floral reward, whereas only the male plants offer pollen. Male bays may be mowed to induce re-flowering.

Fig. 3.

There was no effect of pollen trapping on the amount of sealed brood in pollen trapped (light gray) versus untrapped (dark gray) colonies over the duration of canola seed pollination. Both trapped and untrapped colonies increased in the amount of sealed brood per colony between the initial and final assessments. For each box, the lowest part of the shaded box represents the 25th percentile, the solid line is the median, the dashed line is the mean, and the top of the shaded box is the 75th percentile. Whiskers represent 5th/ 95th percentile, and dots represent outliers.

Fig. 4.

The placement of pollen traps and active collection of pollen significantly reduced the honey production of trapped colonies (light gray) compared to those with no trap (dark gray). For each box, the lowest part of the shaded box represents the 25th percentile, the solid line is the median, the dashed line is the mean, and the top of the shaded box is the 75th percentile. Whiskers represent 5th/ 95th percentile, and dots represent outliers.

Fig. 5.

Colonies that produced more honey also tended to produce more pollen. Each dot represents one colony; blue shading represents 95% confidence interval of the prediction.

Fig. 6.

(A) Colonies tend to be consistent in terms of the amount of pollen they collected per sampling date. The top 10 (black lines) and lowest 10 (red lines) pollen-producing colonies (of 58 total) as ranked on the first sampling date were reliably ranked relatively high or low on subsequent dates, with only a few exceptions. Dashed green line represents the mean weight of pollen collected per date. (B) Mean (dashed line) ± 2 SE (solid lines) for the top (black lines, n = 10), middle (grey lines, n = 38), poorest (red lines, n = 10) pollen-producing colonies. Note that the ±2 SE of the top producers does not overlap with lower producing colonies at any date. That is, the top performing group of colonies remains the top performing at all dates.