What's New from Beescience?
Thiele und Thiele Consult - Publications
It can originate effortless the impression, that too many actors in the range of the natural bee keeping and books to this theme get taken in my publications under the magnifier and disregarded will be the bee science. But this is not so. The newest knowledge from beescience get also discussed, so for example in the 72nd Letter (letters on organic beekeeping and more... part III).
In the 80ies of the 20th Century the hypothesis, the longer a summer bee may live, the more often they may fly out to forage nectar or honeydew, was the cause for doing research on genetically bound differences in the lifespan of the worker bees. As from a laboratory-scientist of former times not otherwise to be expected, he had, in order to determine the lifespan of the workers, hold them captive in the laboratory without further ado. By taking a bee out of the context of it's colony I should think it's unlikely that it may be able to tell us about it's secrets. Nowadays it is being stated from the scientific side:
"If that behaviour is really suitable to determine the genetically bound lifespan of worker bees, may be questioned. Winter bees don't survive wintertime, if they are being hold captive in cage, they do it only in their colony" (1).
Therefore one is today working with marked bees. In average one may say that a queen lives 3-4 years, a worker bee 6-8 months (so-called winter bees) or just a few weeks (so-called summer bees), and a drone about one summertime. Normally their life will be set an violent end by the so-called drone-battle. Nevertheless there are also exceptions:
"During estimation of populations, by which all combs of a colony has been inspected thoroughly, we still met the male sex at least in one colony of an bee site in autumn. The conclusion 'here's something wrong!' has mostly proven to be wrong after a further observation of the colony in the following" (2).
This is an interesting observation which may indicate that in former times when bee races haven't been treated so much by artificial breeding methods, it may have been rather self-evident that a few drones stay in the colony also during winter period. Mr. Liebig says: "But I suppose almost no drone will succeed in overcoming the winter" (3). Nevertheless it may be possible.
How does the life cycle of a bee colony look like? Also here Mr. Liebig has carried out interesting research. In 1996 June 5 he has put a small colony of about 900 bees together with a brood comb free of brood, a honey/pollen-comb, a freshly hatched queen and 8 empty frames in a magazine. In the end of June, just before the first brood was hatching, the colony had only just 500 bees and a brood nest of 400 cells. Within two months until the end of august, the amount of bees increased to 8.000 bees. In October 10 the colony with about 7800 bees has been prepared for over wintering. During the winter the colony lost only very few bees. In March 6 it still had about 7500 bees and already 8.400 brood cells. The brood nest increased over three months constantly and reached in May 28 it's maximum with nearly 40.000 brood cells. In June and July the colony took care throughout about more than 30.000 brood cells. In August and September the brood nest decreased again, and in 1997 October the colony was free of brood like the year before.
How do you may judge the lifespan of a single bee correctly? One observes the state of the colony in the beginning of it's development, in the case of Mr. Liebig's colony in 1996 June 27 and 21 days later, in June 18. In June 27 the colony had 500 bees and 4.000 brood cells. According to Mr. Liebig the 500 bees of the young colony have been at least 22 days old in June 27. Until the estimation of the population in July 18 these bees must have died. Only these or also still others too?
"But not only these, also a large part of bees who wasn't hatched yet in June 27! In the estimation interval between June 27 and July 18 the colony 19 could had increased to 4.000 bees, on condition that all brood were hatched and no single bee had gone lost. But in fact the colony became just stronger by 1.750 bees. If one starts from the assumption, that the older bees die first, then the 500 bees who have been born in the small colony before June 5, have vanished in the estimation interval; on top of that almost half of the bees who have hatched in the estimation interval. Those have grown in average not even two weeks old" (5).
A similar result brings the next estimation interval between July 18 and August 8. In many textbooks you can find a lifespan of 4-6 weeks. This would mean, that a brood maximum of 4.000 cells leads to a colony strength of 50.000 to 80.000 bees. Only rarely counts a colony more than 40.000 bees in summer according to Mr. Liebig, although in the observation period from 1996 July to 1997 October more than 275.000 bees have hatched! But in the same time period also more than 265.000 bees have died. Mr. Liebig therefore concludes:
"In 1997 from April to August the summer bees of the colony #19 have grown in average between 2 and 3 weeks old! That result is no single case, but the rule. Therefore is the claim one finds in many 'textbooks' regarding the description of the lifespan of the workers, according to which the workers become a forager only after three weeks 'in-door-duty' and continue to forage for once more three weeks, not correct" (6).
Upon which factors does the lifespan depend? By far the most important is taking care of brood. The more a bee colony rears brood, the more short-lived are it's workers. Nevertheless the colonies grow in springtime the more they are rearing brood. And because it is on top of that well known that the effectively of breeding in springtime depends to great extent upon the amount of bees, the strength of the colony in the end of winter has a key function for the further colony development. Mr. Liebig says there is a simple rule: more bees - more brood, more brood - more bees etc. (... and more honey). The foraging during a honeyflow doesn't seem to influence the lifespan of the summer bees at all; because in "lazy" colonies workers don't live longer than in "hard-working" colonies. Also the processing of liquid or stiff fodder, which is given to the bees for feeding of young colonies or for making winter fodder, has according to Mr. Liebig, no effect on the lifespan of the workers. Those don't live longer, if they get syrup or fodder in form of caped honeycombs instead of sugar water. Even if there are no differences - as Mr. Liebig maintains - between the kinds of fodder, the bees are not more preoccupied regarding processing of sugar water, stiffed fodder or syrup, thus, the whole colony is going to be strengthened by a winter fodder containing a special herb tea (7) and honey from own apiary.
"Breeding can neither be stimulated by a flow of nectar or honeydew nor by feeding. Compared with that it is possible that the brood nest is being restricted by a heavy honeyflow or feeding, which has a positive effect on the lifespan of the workers, who don't have to take care about the brood" (8).
Summer bees being short-lived is an essential property of a colony, which is only little influenced by the environment. It is the expression of a high bee-turnover, which is during brood-period being strived for by all colonies no matter what origin and which sense may be to prevent the outbreak of diseases (9). That biological defense against diseases should not be weakened by beekeeping methods, thus as a complete weakening of the colony not by artificial insemination and grafting.
- Liebig, G., 2002: Über das Lebensalter der Bienen. Kurzlebigkeit ist die Grundlage der Bienengesundheit. Deutsches Bienenjournal 10 (2): 48-50. Berlin, Germany.
- See Internet Course # 01 und #02. Bad Sooden, Germany.
- Liebig, G., 2002, see note 1.