BERT’S BEE BLOG – June 2022
Welcome to the June Blog.
Last Month we examined the benefits of having some awareness or knowledge of our local flora. This month we will in consideration of this knowledge now examine the sources of nutrients for bees.
Bee Nutrient Sources.
I have considered this aspect of my beekeeping critical and have attempted to plan this when planting species around my property. For example, I have grown pumpkins close to my colonies as the pollen of pumpkins are reported to be high in protein (around 28%) I understand. I might suggest that this has had a positive outcome for the bees in the past.
So, I am suggesting that some thought should be given to the potential nutrient content of plant and tree species within the forage limits for our bees. Now, this may prove a challenge in some circumstances however if we have a reasonable awareness of the available species around us and their potential nutrient content this may inform the recommended planting within our control. There are significant references that can inform the recommended protein percentage levels by species so again some research can be beneficial.
Most of this month’s blog information has been sourced from the Honeybee Nutrition Review of research and practices a report for the Rural Industries Research and Development Corporation by John Black.
According to the above report Nectar is the main energy source for bees and is mainly consisted of sugars and water. Some common sugars include, sucrose, glucose, and fructose, however nectars also contain galactose, mannose, maltose and raffinose (Waddington, 1987). Of interest is the variation of % of sugars in nectar said to be between 4 and 70% (Waddington, 1987; Herbert, 1997). Another important fact to have some awareness of is the actual potential for nectar volume variation from very limited quantities up to 5.5 uL (Waddington, 1987). Just for interest 1mL = 1000 uL.
Some flower species can also contain limited amounts of amino acids, protein, lipids and free fatty acids, other fragrances, organic acids, and minerals. These additional concentrations of amino acids vary by flower species, (Baker and Baker, 1975).
It is of interest and certainly noteworthy that the concentration of sugars in nectar, the quantity of nectar per flower, the variation in nectar volume and the morphology of the flowers have a significant effect on the foraging behaviour of the bees (Waddington, 1987). There are other factors that affect foraging behaviour of the bees and selection of flowers including distance from the hive through its effect on energy required for bees to fly to the nectar source and additionally the difficulty involved in the collection of the nectar. It should be noted that the metabolic rate of the resting honeybee increases approximately 10-fold from 5 to 50 ml O2 consumed/mg/h as ambient temperature decreases from 36 degrees to 5 degrees C (Cahill and Lustick, 1976).
According to Black, 2006, honeydew is a rich source of carbohydrates excreted by aphids that feed on the sap of plants. Bees are known to collect honeydew as a source of carbohydrates (Moritz, 1999). Bees do not actively seek out aphids but collect droplets of honeydew from leaves and other plant surfaces. According to Wolf and Ewart, 1955, the mineral content is higher, and the honeydew contains a greater proportion of oligosaccharides such as melizitose and fructomaltose.
Pollen is said to provide bees with the main nutrients for their growth and development. Pollens contain significant nutrients including proteins, amino acids, fatty acids and sterols, carbohydrates such as sugars and starches, minerals, and vitamins. According to Waddington (1987), pollens also contain a range of cell wall constituents including cellulose, pectin’s and the sporopollenin matrix. Studies of the composition of pollen in Australia have been extensive and include pollen from 75 plant species from Kleinschmidt (1993), and 194 pollen samples from 55 plants species by Somerville (2001). Many of the analyses have been for protein and amino acid content, but others have investigated fat and fatty acid concentrations, sugars and starches, fibrous components, vitamins, and minerals.
In consideration of some reported protein levels, it has been observed by Somerville (2001) for pollen collected in Australia was 9.2% for flatweed (Hypochoersis radicata) to 37.4% for one sample of pollen from Paterson’s curse (Echium plantagineum). According to Kleinschmidt (1993), the range in protein content of pollen from eucalypt species obtained ranged from 24% to 37%.
This is an extremely extensive topic with many studies conducted over a significant period. The variation in results and the extensive range of species involved makes this topic far from routine. I do consider some knowledge of the potential for local resources valuable, and it will become obvious when observing the bees foraging in your local area and within the boundaries of your own property, the species that they find most valuable. We have only scratched the surface of this fascinating subject with the potential for much more knowledge to be gained.
Black, J, May 2006 Honeybee Nutrition, Review of research and practices, RIRDC Publication 06/052, May 2006
Waddington, K.D. (1987). Nutritional ecology of bees. In Nutritional ecology of insects, mites, spiders, and related invertebrates. Pp. 393-419. F. Slansky and J.G. Rodriguez (Eds). Wiley, New York.
Baker, H.G and Baker, I. (1975). Studies of nectar-constitution and pollinator-plant coevolution. In: Coevolution of plants and animals. Pp. 100-140. L.E. Gilbert and P.H. Raven (Eds). University of Texas Press, Austin, USA.
Moritz, R.F.A. (199? **) Nourishment and sociality in honeybees. In:??? Rob Manning supplied copy?
Wolf, J.P. and Ewart, W.H. (1955). Carbohydrate composition of the honeydew of Coccus hespsridum L. Evidence for the existence of two new oligosaccharides. Archiv fur Biochemie und Biophysil 58: 265-372.
Kleinschmidt, G. (1993). Colony nutrition on the Atherton Tableland. The Australian Beekeeper 95:453-464.
Somerville, D. (2001). Nutritional value of bee collected honey. A report to the Rural Industries Research and Development Corporation RIRDC Publication No. 01/047. Rural Industries Research and Development Corporation, Canberra, Australia.
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