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Winter Losses in Honey Bees,
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Most of us direct a great part of our autumn effort towards preparing bees to winter with a minimum of losses. During the winter our constant worry is lest unforeseen mishap should befall the stocks in our care. And in springtime, those stocks which have come through winter weakly, or with obvious failings, are fed and given new combs, if not helped with brood or bees from more successful stocks, to ensure that they do not go under. In view of this, how can anyone suggest that winter losses are a necessary part of efficient strain maintenance?
Let us look at the position more closely... Stocks die from three causes:-
- chance or accident
- bad management
- inherent genetic lack of winter hardiness
We usually get combinations of two or three of these effects acting together.
Some stocks obviously die from pure chance... This winter [1966, Ed.] some cattle got into an out apiary at Castle Donington, and knocked seven hives out. This must have been about Christmas, but I didn't discover the occurrence until early February, by which time two hives were completely inverted and minus their floors, and the bees were found to have perished. The remaining five stocks were less badly damaged, and survived little the worse for wear, though rats and woodpeckers had taken their toll of the combs. The hives that got turned over were those most in the path of the beasts who broke through a hedge near by. Such losses, even if attributable to bad management, were due to chance as far as the bees were concerned: losses were likely to occur in random manner, distributed on a chance basis between winter hardy and winter susceptible types of bee.
But suppose that we had not just had the wettest January that this area has known for many years, and I had not been away from the apiary so long. Might not the bees have survived had they been hardier? Or might not more of the seven have succumbed had they been softer? Although chance comes into it, in that the remaining thirteen hives, soft and hardy alike, were not touched, vigour comes into it as well. When we analyse our losses in springtime, do we try to weigh up how much of the losses are due to one cause or another?
If large numbers of stocks that have died are analysed, it can sometimes be deduced that only a relatively small number have died from "chance" causes. There is, of course, the exceptional misfortune that knocks out whole apiaries, of whatever strain or method of management, be it flood, vandalism, certain aspects of disease, or the harmful effect of giving acid inverted candy prior to and during an exceptionally hard winter. These things strike against vigorous and weak alike, with complete impartiality.
Let us look now at management... Rarely does one single omission of management operate alone in curtailing our spring count. Perhaps we did fail to feed enough food to some stocks, and they could have got through by giving them more sugar, or taking off less honey. But had they been good conservers of stores, packing it well down into the brood box, and not breeding too late into the autumn, they might well have come through the winter in perfect safety, though perhaps late to build up in spring. Management has shown up ten inherent genetic weakness. Heredity may be more to blame than our management.
Management would have been more suspect had we raised young queens in late summer, in small nuclei, then allowed them to build up on their own. Wasps would have found them an easy prey, and if fed late, the bees would have had little opportunity to build up to reasonable wintering numbers. Our management would have contributed more than genetic make up towards any winter loss. But this year it has not been at all a bad winter, with cold spells of short duration, and ample opportunity to fly, and I know beekeepers with three frame nuclei of native bees who appear to have got all of them through in this area. Had it been exceptionally cold it might well have been otherwise, but native bees seem capable of wintering in very small clusters if they can be kept dry, eating hardly any honey under such conditions.
Ah, I can hear you say, but disease strikes impartially. And many bees succumb to disease in winter. Yes and no! Heavy disease will wipe out any stock. But moderate disease may wipe out some, but not others. After the prolonged 1946-7 winter, when I lived in south Lincolnshire, I made a survey of stocks which had died from starvation. Eighty seven per cent of dead colonies showed signs of acarine disease, but only 8 per cent of the survivors. There, you will say, that just goes to prove that acarine disease can be lethal in winter. But wait... That is not the whole story. These bees, in fact, mostly died of starvation, and yet, by hindsight, we are blaming it on acarine.
Part of our study in that and subsequent years, compares bees wintered on a single B.S. brood box, with those on a double tier of brood boxes. We found that bees with even heavy acarine infestations would usually winter safely, if they had enough food. Infested stocks tended to behave in winter as if disturbed and uncomfortable, individual bees moving about more than healthy clusters, raising heat and losing it, thus consuming very much more food in winter. Perhaps double brood box hives favour wintering for other reasons than holding more food, but the fact is that a much higher percentage of acarine infested colonies wintered on the large brood box system than on the small. In other words, the smaller brood box appears to strongly select for acarine resistance where the larger one does not (supposing that such resistance is a reality, which we, for other reasons, have cause to believe).
By heavy feeding, or by chemical treatments to eliminate the mites, we are perpetuating the more acarine susceptible strains we could well do without. Is it economic to mollycoddle them through? Would it not be better to count them as "winter losses", and not to breed from them or allow them to produce drones in our apiaries next year? Acarine is not the killer that most people suppose, most of our native bees are highly resistant today, anyway and though amounts of the parasite build up in a poor season, rarely does it seem to cause appreciable economic loss in native strains.
Let us now look at Nosema... Some strains are particularly susceptible to this trouble, while others heed it little. Of course management affects incidence in many ways transportation, wintering on certain types of food, and giving stocks diseased combs, all enhance outbreaks. But even so, some strains are much more prone to a recurrence following treatment, or to build up of trouble under conditions favouring spread of the disease, than are others. Is it not best that we should lose these more susceptible strains in winter, rather than perpetuate them?
It is surprising what bees can stand in winter and still come through... Mice, minimum food, leaky roofs, damp from a host of causes, and even mild degrees of flooding. Damp is probably more harmful than any other single factor, particularly in a very cold winter, when the moisture produced by respiration freezes into stalactites from the quilt or crownboard, to conduct away the warmth of the cluster. This was what killed many very large colonies in the 1962-3 winter, when the smaller colonies, producing less moisture, wintered safely. Management can provide through ventilation, to dissipate the damp, and we may feel that this is just a management problem. Yet some strains of bee can winter under these conditions. And surely it needs this type of selection to upgrade our strains to combat Britain and Ireland's chief enemy, dampness. The mechanisms of wintering on little food, i.e., wintering with the release of a minimum of moisture from the cluster, are now being studied as one of the experimental projects of the Village Bee Breeders' Association. Dr. Paul Wix is Convener of this Project and it is becoming increasingly clear that such losses are only partly due to management, or to the weather. Survivors have a built in survival kit. And we would do well to select it preferentially, by refusing to mollycoddle or to buy those without it.
No! While we do not have to operate such a strict elimination test as some let alone beekeepers put their bees through every winter, we would be prudent to help our bees only so far. The seedsman does not sell as crop plants those weakling varieties that cannot stand up to at least some of nature's rigors. We protect our crops so far by cultivations, fertilizers and weedkillers, but they need to have a great deal of inherent vigour to fend for themselves thereafter. In bees, which are much less selected creatures than most stock animals and crop plants, we must value the regular culling which winter applies.
We are apt to be appalled at the thought that our honey yield will be reduced by such losses, to see our capital in hives and equipment not being utilized, and yet to overlook the appreciable saving which the more vigorous stocks will themselves impart, not just the small percentage gain in the coming season, but the compound interest gain in generations of bees to come.
Yes, winter losses are a national asset... We don't want them to get out of hand, of course. But to perpetuate weaklings is antigenic, and costly in the long run, costly, not just to ourselves, but costly to others in our district: with whose bees our drones will cross mate. We see loss of honey this season staring us in the face, but forget the bigger loss that will in due course accrue from protecting the weaker forms. Farming does not perpetuate very blight susceptible potatoes, nor frost or mildew susceptible wheats, and even high yielding cows are culled if they do not stand up to certain vigour criteria. Flower growers, perhaps, are freer to perpetuate weaker, but prettier forms, but fashion dictates the trend in such amenity crops. Do we keep bees for economic production, or because they are pretty or fashionable?
So those of you who have had losses not entirely due to chance and I suspect this means about 75 per cent of you, don't, please don't, rush to fill your every hive box with imported bees. Yes, I know you're as impatient as anyone to see tangible signs of spring pouring forth from the hive entrance. But, in the long run, it is better to propagate from your more vigorous survivors rather than import bees from another climate. I know the advertisements of foreign bees sound glowing, and you know the faults of your own, or of the man with bees for sale down the road. The grass is always greener in the next field, so they say. But is it? Usually not. So be patient. Upgrade your own, or utilize your district's bees. And if your district's bees are not vigorous, it is probably because your predecessors have not tried to look far ahead. And why not now help those of us who are working towards more vigorous bees for these islands, through the Village Bee Breeders' Association?
The winter cull is natural selection at work before our very eyes and is a necessary part of strain maintenance and improvement. Do not reject this friend of the far sighted beekeeper.
Beowulf A. Cooper
This text appeared in Bee Craft, Vol. 48, Nos. 4 and 5, April/May 1966 and has also been reprinted in various BIBBA leaflets.
Printed from Dave Cushman's website Live CD version
Written... 21 May 2006, Upgraded... 27 September 2007,
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