The effectiveness of pollination relies not only on the number of honeybee colonies placed in a field, but also on the strength of each of those colonies. The strength of a hive refers to the number of bees in the hive. A hive consists of one or more compartments, called supers. A strong colony has about 15,000 bees in each super. When a strong hive is open, the bees move so much that they nearly appear to "boil" out and should cover the top of the frames. This is less apparent if the weather is fine and the bees are gathering nectar and pollen outside the hive. For the pollination of wild blueberries, a hive should have at least two supers (Figure 1) and contain a laying queen, brood, and 25,000 to 30,000 honeybees.
Hive Strength and Blueberry Pollination
Fig. 1 Two hives, demonstrating (A)
one super and (B) two supers
Fig. 2 In a strong colony, plenty of bees can be seen at the top of the frames
A quick indication of hive strength can be taken by observing activity at the hive entrance. On a warm sunny day, a dozen bees should be seen entering and exiting the hive at any one time. In addition, if the bees are returning with pollen loads on their back legs, this means that they are collecting pollen, and are therefore pollinating the flowers. These types of observation should never be made by standing in front of the hive, since the bees returning from the field will be unable to enter the hive.
At the time of wild blueberry pollination, a strong colony contains pollen and honey reserves, as well as brood. The weight of the hive is also another indicator of colony strength. Using slow movements, the hive can be lifted slightly from behind, by taking hold of the back end of the bottom board. Leaning the hive slightly forward will give a general indication of the weight; if it is difficult to lift, the hive is likely to be good and strong. For this test, it is advisable to wear the beekeeping veil and bee-proof gloves (at the very least), and preferably the full beekeeping outfit. It is also advisable to consult with your beekeeper.
These methods can only hint at the actual strength of a colony, however. The surest way to determine colony strength is to inspect the inside of the hive. A beekeeping suit is essential for safety during the opening of a hive. If the hives are rented, ask the beekeeper to open a few hives in your presence. His skill and knowledge of bees will result in minimal disturbance to the hive. This is how a hive inspection is performed:
- When the inner cover is lifted, there should be dozens of bees present in the frames.
- Next, the beekeeper should separate the two supers. Plenty of bees should be visible between the frames in each super (Figure 2).
- Request that the beekeeper removes the frames one by one in order to determine the total number of frames which contain brood. These brood frames contain eggs and larvae of all ages. At the onset of the wild blueberry pollination season, a hive should contain the equivalent of 5 frames, with at least 50 % of the area filled with brood and several dozen bees on each frame (Figure 3, page 4). If the population of bees is weak, only small quantities of bees will be grouped together, and these will be located on the centre frames.
Fig 3 Photograph of a frame, showing approximately 60% of the area filled with brood, and several dozen bees on the frame.
Conseil des Productions Végétales du Québec. 1977. Apiculture: Emplacement du rucher et dérive. Agdex 616. 4pp.
Hoopingarner, R.A. and G.D. Waller. 1992. Crop Pollination. In The Hive and the Honey Bee (Joe M. Graham, editor). Dadant & Sons, Hamilton, Illinois.
Karmo, E.A. 1978. Blueberry Pollination - Problems, Possibilities. Beekeeping Fact sheet 109, NSDA, Nova Scotia, 11pp.
Pacific Northwest Extension. 1984. Evaluating Honey Bee Colonies for Pollination. A Guide for Growers and Beekeepers. PNW Publication 245, 6pp.
Root, A.I. 1993. ABC and XYZ of Bee Culture. A.I. Root Company, Medina, Ohio. 500pp. Vickery, V.R. 1991.
The Honey Bee: A Guide for Beekeepers. Particle Press, Pincourt, Québec, 250pp.
Prepared by: Bernard Savoie, P. Ag., Horticultural Technician; John Argall, Provincial Blueberry Specialist, N.B. Department of Agriculture & Rural Development; and Heather Clay, New Brunswick Beekeepers' Association.