A good supply of pollen is essential to a honeybee colony because…
… bees cannot live on honey alone. While the sugars in honey supply the bees’ energy needs, in addition they require the protein, fats, minerals and the miscellaneous dietary supplements found in pollen. The protein content of the pollen of different plants is variable but generally very high, containing amounts comparable with peas and beans (Witherell), or seeds and peanuts (Dietz).
Protein is important because it is the building material for growth and tissue repair. As a measure of the importance of the protein in pollen, it has been shown that the amount available to a colony influences the size and quantity of the emerging brood. In fact it has been calculated that the amount of pollen required to rear a bee – from the hatching of the egg to the emergence of the adult – is between 120 and 145mg.
But it doesn’t stop there because young bees continue to grow after emergence. On average, emerging bees contain 13% protein (Witherell) but by the time they are 5 days old, the heads, thoraxes and abdomens of young bees contain 93%, 38%,76%, more protein respectively than those of the newly emerged (Dietz). This huge increase is brought about by a massive consumption of pollen which is initiated within a very short time from emergence, perhaps as little as two hours, and rises to a peak at about 5-9 days old before gradually diminishing and eventually tailing off at 15-18 days (Dietz). However not all this protein intake is used in growth of the bee or development of the hypopharyngeal glands because it is on about the 3rd day after emergence that the bees are directly employed in brood rearing, an activity that continues up until about the 13th day (Gary) and involves the passing on of pollen-derived protein to larvae in bee milk.
During brood rearing, a nurse bee needs to digest about 10mg of pollen to produce 4mg of protein per day in brood food which is produced in the hypopharyngeal glands. The more protein that is available to the nurse bees either by concentration in, or sheer bulk of, pollen the more larvae a bee is able to feed.
The likely effects of a shortage of pollen in late summer and autumn are…
…that the amount of pollen the bees manage to store will be insufficient to take them through to April and the start of the season proper. The significance of this is that the queen perks up and starts to lay, albeit at a slow rate, very early in the spring and long before fresh pollen becomes available in any sort of quantity. At this time nurse bees need to increase their pollen intake to kick-start their hypopharygeal glands so that they will be able to feed the emerging brood. If the required pollen is not there, it could mean that the colony will be unable to feed the larvae properly resulting in small bees and a possible late start into the season.
The bottom line of all this could be a reduction in colony strength especially if spring, and summer for that matter, are delayed, poor or cancelled altogether. A late start to the season could also mean them failing to make the most of the early flows such as dandelion and even hawthorn. More generally it could leave the colony weakened and vulnerable to all of the assorted brutalities of nature.
This situation arose in the spring of 2013 which became very cold and continued forever. The effects of this were made worse because it followed a miserable autumn where the bees failed to work the ivy to any significant extent. And of course the autumn of 2012 followed the most disastrous summer for beekeeping in history with record breaking queen failure because of the atrocious, striped weather. But don’t get me started.
It is advisable to keep a stock of pollen supplement or substitute for situations such as this. In that terrible spring it was impossible to buy supplement or substitute because of course everybody was in the same boat. Click here for a recipe for pollen substitute from the Scottish Beekeepers but be careful to buy GM free ingredients.
Some sources of pollen in Ireland …
… in this locality sources of pollen include:- Snowdrop, Crocus, winter Ericaceous heathers Hellebore, Gorse, Hazel, Willow, Dandelion, Currants black and white, Oilseed rape, Hawthorn, Apple, Pyracantha, Cotoneaster, Sycamore, Horse chestnut, Clover, Raspberry, Lime, Blackberry, Thistles, Ragwort, Knapweed, Native Ling and Bell heathers, Ivy, Mahonia.
Principal constituents of pollen…
…in addition to protein and lipids (fats) pollen contains:
- free amino acids;
- carbohydrates (sugars, starch and cellulose);
- minerals (calcium, magnesium, phosphorus, iron, sodium, potassium, aluminium, manganese, sulphur and copper);
- vitamins – pantothenic acid, nicotinic acid, thiamine, riboflavin, ascorbic acid and small amounts of vitamins D and E;
- enzymes and coenzymes;
- pigments xanthophyll and carotene;
- sterols (Witherell).
Because these ingredients are so variable between different pollens, it is thought that bees need a good mixture of pollens to be sure they are having a balanced diet.
An example of this could be bees in America where they tend to have single species diets for blocks of time throughout the year due to migratory beekeeping and very regimented agriculture. This is thought to be a contributory factor in Collony Collapse Disorder (CCD).
References and Bibliography
Dietz,A. Nutrition of the Adult Honey Bee. In The Hive and the Honey Bee. Ed. Dadant and Sons. Dadant Publications. Illinois. USA. 1979.
Gary,N.E. Activities and Behaviour or Honey Bees. In The Hive and the Honey Bee. Ed. Dadant and Sons. Dadant Publications. Illinois. USA. 1979.
Hooper,T. Guide to Bees and Honey. Blandford, London. 1991.
Witherell,P.C. Other Products of the Hive. In The Hive and the Honey Bee. Ed. Dadant and Sons. Dadant Publications. Illinois. USA. 1979.
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