As a conservative estimate, insect pollination contributes to 1/3 of global food production but there are differences in how individual insect species achieve pollination. Depending on the type of bee, different pollination techniques are used with varying effectiveness depending on the type of flower they are pollinating. Today we are going to be focusing on honeybees and bumble bees to contrast their effectiveness as pollinators. 

Honey Bee and Bumble Bee Pollination

 

Pollination is the process of transferring pollen from flower A’s stamen to flower B’s pistil to allow fertilization. In the case of the wild blueberry plant, as a floral example that will be used throughout this blog, the result of this reproductive process is the seed, carrying fruit. Insects are attracted to flowers as a food source and passively transfer pollen when visiting multiple flowers. When a bee approaches a plant, pollen from the flower's stamen, via electrostatic mediated transfer, binds to their hairs. They then fly to the next flower and, via the same reversed forces, transfer pollen to this second flower.

Figure 1. A tri colored bumble bee (Bombus ternarius) pollinating a wild blueberry plant (G Dugas, 2023).

Bumble bees and honey bees are similar in that they both visit flowers to collect pollen and nectar. That is where the similarities end. Each differ in the amounts of time per floral visit, as well as amounts of pollen and nectar carried. When it comes to floral visits, bumble bees are much faster. They visit up to 11.5 flowers per minute, where as a honey bee will visit up to 9.2 flowers per minute (Couvillon et al. 2015).  A honey bee can carry, at max, 80% of its own body weight in pollen and nectar but on average only carries 35% or less (Feuerbacher et al. 2003).  A bumble bee carries around 23% of its body weight in pollen and nectar on average but up to a maximum of 91% nectar and pollen to body weight (Mountcastle et al. 2015). So, bumble bees are the workhorse when it comes to collecting pollen and nectar. 

Table 1. Comparison of Bumble Bees and Honeybees

Pollination Feature	Honeybees	Bumble Bees
Colony size	30 000 insects	150 - 300 insects
Floral choices	Generalist (polylectic)	Generalist (polylectic)
Pollination behaviour	Passive adherence (Accidental Pollination)	Floral Sonication            (Buzz Pollination)
Minimum Foraging Temperature	15⁰C	12⁰C
Optimal flight temperature	20⁰C	25⁰C
Max. flight temperature	42⁰C	27⁰C
Flower visitations per minute	9.2/minute	11.5/minute
Foraging distance	6 km	< 2 km
Foraging light requirements	Bright light	Low light (dawn & dusk)
Relative tongue length	Medium	Long

The methods used by honey bees and bumble bees to extract pollen, and thus allow pollination to occur, differ.  Bumble bees use what is called floral sonication or buzz pollination while foraging. This method involves vibrating the flower to allow pollen to be released from the anthers and the audible sound created is a buzz (De Luca & Vallejo-Marin, 2013). Wild blueberries plants have evolved to specifically release pollen in this way. Pollen is released via small apical pores from poricidal anthers (the part of the stamen which contains pollen). These specially adapted anthers restrict pollen accessibility which is why honey bees forage only for wild blueberry nectar as the pollen is less available to them. Native insects, like bumble bees, have coevolved with the blueberry plant in a symbiotic relationship. The blueberry plant restricts pollen collection to these bees and the bumble bees in turn provide efficient pollination. This is the reason why, individually, bumble bees are more efficient than honey bees at pollinating wild blueberries. Of all the insects which pollinate wild blueberries bumble bee queens (Bombus spp.) are the most efficient (Bushmann & Drummond, 2020).

The advantage that honey bees have over bumble bees when being used for pollination is the size of honey bee colonies.  A strong honey bee colony will contain 20 – 30,000 individuals and a bumble bee colony will only contain up to 300. So, the workforce of a honey bee colony is far greater than a bumble bee colony. Honey bees are not a native species to eastern Canada and have a narrower range of temperature and light in which they will fly. Native pollinators, like bumble bees, will fly and pollinate, at lower temperature and on darker days typical of our region's climate. Again, the honey bees, will make up for their more selective flying by turning out is greater forces in favorable conditions. Also, there seems to be a rebound effect, that after a period of poor flying weather, honey bees with their large colonies, can put an increased number of foragers in the field. Table 1 contrasts honey bees and bumbles bees in their foraging and pollination efficiencies.

Honey bees and bumble bees pollinate very differently. As managed pollinators, they both have advantages and disadvantages. The reality is that optimal pollination may be achieved when they are used together. Native pollinators are also important in food production and good for the environment. Without bees of all types, production would be limited to the point of food scarcity. The next time you see a bee, take the time to observe, watch it work and be appreciative. 

      

            Written by Gregory Dugas, ATTTA Seasonal Apiculturist - gdugas@perennia.ca

 Connecting with ATTTA Specialists

If you’d like to connect with ATTTA specialists or learn more about our program, you can:

visit our website at https://www.perennia.ca/portfolio-items/honey-bees/

Email abyers@perennia.ca

References

Bushmann S & Drummond F (2020). Analysis of pollination services provided by wild and managed bees (Apoidea) in wild blueberry (Vaccinium angustifolium Aiton) production in Maine, USA, with a literature review. Agronomy 10(9), p.1413.

Couvillon M, Walter C, Blows E, Czaczkes T, Alton K, & Ratnieks F (2015). Busy bees: variation in insect flower-visiting rates across multiple plant species. Psyche 2015.

De Luca P & Vallejo-Marin M (2013). What's the ‘buzz’ about? The ecology and evolutionary significance of buzz-pollination. Current opinion in plant biology 16(4), p.429-435.

 Drummond F (2012). Commercial bumblebee pollination of lowbush blueberry. International Journal of Fruit Science 12(1-3), p.54-64.

Feuerbacher E, Fewell J, Roberts S, Smith E, & Harrison J (2003). Effects of load type (pollen or nectar) and load mass on hovering metabolic rate and mechanical power output in the honey bee (Apis mellifera). Journal of Experimental Biology 206(11), p1855-1865.

Mountcastle A, Ravi S, & Combes S (2015). Nectar vs. pollen loading affects the tradeoff between flight stability and maneuverability in bumblebees. Proceedings of the National Academy of Sciences 112, p10527-10532.

Peat J & Goulson D (2005). Effects of experience and weather on foraging rate and pollen versus nectar collection in the bumblebee, Bombus terrestris. Behavioral Ecology and Sociobiology, 58, pp.152-156.