web : http://www.apisjungels.lu
Topic for discussion:
Publish in French in
Abeilles & Cie, the CARI asbl
No 90, october 2002, 9-13, et
No 91, december 2002, p??
Original : Auswertung von Bienenvölkern
Möglichkeiten und Grenzen der Zuchtbetriebe.
In: Der Buckfastimker
Nr 10(Heft 4), 2001 Seite 6-22.
The discussions forum of the buckfast bee-keeper
LU-9361 - Brandenbourg, Lux.
web : http://www.apisjungel.lu
Paul Jungels is well known as a selective breeder of Buckfast bees. He gives here an account of his practical experience and is freely prepared to show the full extent of what he has been able to achieve in his work. He has adopted this candid approach with a view to canvassing any observations, comments and suggestions you may care to make.
Below an example of a simple and quick evaluation table.
|number||year||Pedigree||of Bees||of Brood||of bees||tendency||dity||Early||Summ.||Late||wintering||Combs||Propol.||number||VSH+||HYG+|
|214||00||B134 ins B106||4||5||5||6||4||5||4||-||6||5||5||4||-||3|
|259||00||B240 ins B106||4||5||5||6||6||4||5||-||4||5||5||5||-||5|
|286||00||I230 ins B106||5||4||5||4||5||5||5||-||5||5||5||5||-||5|
|158||00||A199 bal B106||4||5||5||5||5||5||5||-||4||4||5||5||-||3|
|Evaluation scale: from 1 to 6. 1 = very bad. 3 = bad average. 4 = good average.|
5 = great performance. 6 = optimum looked for in this feature.
When several breeders are working together, for example in federations or selective breeder groups, it is essential to achieve standardisation of the evaluation results for bee colonies. There is a temptation to lay down precise rules. If, for example, we take the characteristic ”gentleness/ aggression“, we can define it as having the value 4 (or 5 or 9, which is immaterial) on a scale from 0 to 10 for a colony which ”can be inspected without smoke, with no risk of stinging or absconding etc…“. For professionals who find themselves manipulating colonies ”throughout the year, at any time of day, whatever the weather and in areas of varying nectar sources“ these rigid schemes can lead to surprising results. I think it most unlikely that objective evaluations of colonies can be made on the basis of such schemes.
Behavioural conditions and the environmental constraints in which bees operate are more variable than in any other sector of agriculture. Vegetation (cultivated and natural) and climate vary from year to year. In addition it is important to take into account the local microclimate, the state of the soil, temperature and humidity which affect the conditions of each hive. Performances of the colonies are not the only factors subject to these variables. A series of other characteristics such as gentleness, swarming behaviour, disease resistance and viability can also vary considerably. The whole is entirely made up of inter-related parts. So it is that viability will depend on the resistance of bees and brood to disease which itself depends directly on the abundance of pollen and nectar which in turn is a function of climate.
However that may be, we shall endeavour to explain below the whole selection procedure which we apply in our own breeding programme.
From a genetic point of view, the ideal would be to be able to draw a distinction for each colony between the infestation of one or more diseases and an intrinsically low viability measure. In practice these two features are to a large extent linked. It is found that bees of low viability — with shared paternity for example- suffer from diseases during the critical phases of the annual development. This is the case for example in spring in the transition period between the winter bees and the new year’s young bees. During the summer build-up there are signs of an increased proneness to the viral diseases (slow or acute viral paralysis). Normally this loss of viability can be recognized through a sudden drop in the strength of the colony between the spring harvest and the woodland flow (summer). For reasons as yet unknown this woodland honeyflow encourages viral infestations particularly during the main phase of brood expansion. ”Intensity of brood activity falls away at the start of a major flow“ since the colony massively increases the number of bees sent out to forage. There are probably a number of interdependent factors here which would be worth closer study.
Viral infestations moreover take on a further dimension in relation to varroosis. It is now known that untreated colonies or very few, are not destroyed by the direct effects of varroa but rather by secondary, for the most part, viral infections. Both brood and adult bees alike are afflicted without discrimination.
Assessment is made of the relationship between the extent of the surface area of the brood nest and the size of the bee population taking into consideration the longevity of the individual. Account is also taken of the capacity for regeneration of the bee population following an intense honeyflow which will have caused the departure and loss of a great number of workers. In normal conditions any colony showing the slightest sign of disease is immediately down-rated. Of course one proceeds with caution in the absence of those local conditions which encourage viral diseases during the summer months — site, woodland flow or its absence. At the end of summer/autumn if there are signs of varroa damage while varroa drop appears normal, then previous assessments are adjusted.
The aim is clear. What is sought are populations of adult bees without the slightest sign of disease!
The aim seems to have been achieved for all diseases linked to spring development and winter losses are negligeable. The following are the areas which would benefit from improvement; principally resistance to viral attacks during the summer particularly in connection with varroosis. Generally I consider improvement in workers’ longevity a worthwhile aim.
Generally speaking a very compact brood nest corresponds to healthy and fully viable brood. As diseased brood cells are cleaned out by the bees, gaps appear. These are the signs of brood ”disease„.
In the front rank of all the visible diseases, we find ”chalkbrood„ (ascospherosis): a fungal attack which is immediately detectable at the flight entrance by the presence of chalk-white coloured mummies cleared out by the bees.
Sacbrood (viral disease) also appears occasionally.
The conditions which give rise to the appearance of brood pathologies are the same as those for the problems encountered with adult bees (see 1). So for example there is virtually no colony which does not present a number of cells of chalkbrood in extreme conditions — that is during the spring build-up, on the return of cold weather and/or of a shortage of food in March or April or again in the presence of certain stress factors (varroosis, imidaclopride?).
Brood with empty cell patterns is not solely the result of brood disease. Precisely the same symptoms may be observed in cases of major consanguinity. In this case the sexual alleles — which should be different for the female — are most frequently similar. This gives a diploid male which the bees eliminate immediately. Consanguinity is also responsible for other lethal factors which have been described but which are difficult to define. Since it is necessary to distinguish the origin of gaps in the brood (due either to over-close consanguinity or to diseases) in order to make an assessment, in practice only visible brood damage is taken into account.
A problem arises with a major infestation of varroosis. The test for detection and elimination of diseased or dead brood is one of the most reliable of selection criteria. In this case too the brood pattern is marked by gaps. Consequently varroa attacks should be taken into account in assessing brood viability particularly at the end of the active season.
Logically brood viability is assessed in spring and summer during periods of maximum build-up. The best rating is given if the brood is free of disease even during critical phases. Down-rating is immediate if during appropriate weather or harvest conditions defects show up in the brood pattern.
Account should be taken in evaluation of a colony closely related or of pure race, of the brood eliminated before capping. At the end of summer consideration should also be given to the effects of severe varroa infestation.
As for point 1, Bee viability, a brood should be obtained which does not present the slightest sign of disease and bees capable of rapidly disposing of cells affected by harmful organisms such as varroa.
Despite the strength of its populations, the Buckfast bee — reared by ourselves — displays average resistance to the various brood diseases. Certain crosses enable us to vary this factor. Over the last five years, while laying no claim to perfection, we have obtained a decided improvement in sensitivity to chalkbrood. Today the results of our Buckfast bees matches the best highly reputed Carniolan bees.
The Buckfast bee with which we work is, almost universally and justifiably, thought to be the gentlest of bees. At the other end of the behavioural scale lie the crosses of the Iberian bee or the Southern French with the Carniolan — both of which are European! I do not know if the africanised bees of South America are even more aggressive —. Gentleness makes the beekeeper’s work easier. However this begs the question: is it not simply a matter of the loss — at least partially — of a total series of characteristics which represent a defence mechanism of the bee colony. What is more this loss could affect other specific features. From this perspective the question naturally arises as to whether or not extreme gentleness is compatible with a defence strategy against parasites like varroa. Currently at any rate a series of observations has shown that very great gentleness is matched by absolutely passive behaviour in the presence of varroa. However the phenomenon has not yet been made fully clear.
It is for this reason that in recent years breeding objectives have been reviewed so that instead of seeking extreme gentleness whatever the season, at best the aim has been average gentleness enough to allow rapid manipulations.
On the other hand we do not tolerate any following behaviour. This is a defect of every subspecies of A.m. mellifera of Western Europe and perhaps a number of eastern races.
One should be aware too that in the same colony gentleness is subject to fluctuations in the course of the year. Defensive reactions observed vary according to the temperature as well as according to the scale and duration of operations. In spring during an oilseed rape flow all colonies behave much more defensively than in high summer, just as they do on cold damp mornings or at the end of the day.
The undoubted importance of gentleness should encourage the breeder to make it a priority objective. With such obvious results, achieving and maintaining it should not be an issue!
Opportunities for evaluation during the year are more than adequate. Initial assessments should be made during the oilseed rape flow. These may be corrected or adjusted later in the season. A rating will obviously be ascribed on the basis of stinging, actual or attempted but also on agitated movement on the comb during manipulations as well as any excessive flying up of a mass of bees at the slightest jolt.
In short, if a colony can be manipulated quickly and without protective gear during the oilseed rape flow it earns a good score for gentleness. The rating will also take into account the possibility of a thorough inspection of a colony early in the morning or in cold weather.
Gentleness should make it possible to manage colonies in any season. No following behaviour can be tolerated. In summer in fine weather, it should be possible to do without protective clothing.
The aim has been achieved and even exceeded. What is more we hope that in the future, naturally fertilised daughters of our pure-bred queens will produce good-natured populations of bees independently of the males which populate their fertilization zones.
We refer to this issue here since for Carniolan breeders, behaviour on the comb is assessed separately from gentleness.
While it is a characteristic which seriously handicaps manipulation of the bees, agitation on the comb is a particular feature of bees of various origins. First they start running about on the comb, move off it, dangle from the hive, crowd round the circlet of food and hang from the bottom of the frame as it is being manipulated. They end up falling in bunches at the feet of the beekeeper.
Looking for the queen in these conditions can prove hazardous, well-nigh impossible. When at the time of a spring manipulation the bees leave the brood nest certain areas are chilled resulting in the spread of fungal diseases. This can cause areas of chalky brood to appear and develop.
Various crosses including in particular carnica bees with mellifera display an extreme form of this behaviour. In our case pure-bred anatolica as well as meda also display a high degree of agitation. But this feature, characteristic of both races, has already disappeared in the F2 crossing with the Buckfast bee.
Since gentleness and stillness on the comb are easily controlled by crossings, evaluation of behaviour on the comb is associated for us with gentleness.
Bees clinging tightly to the frame is often accompanied by excellent behaviour on the comb. Shaking the bees off becomes virtually impossible. While good behaviour on the comb is desirable clinging too tightly is much less so. If it is possible to have the choice it is worth making the distinction.
This objective of good behaviour on the comb has been achieved with Buckfast bees of pure breed lines. Good behaviour on the comb and gentleness appear to be an outstanding feature of the old established Buckfast line particularly since Dr Mauz and his colleagues have highlighted a clear positive influence among other races in the region. As with number 3, for the future, we hope that our breeding queens will produce daughters which, fertilized by local males in the natural fertilization zones, will continue in calmer behaved colonies.
Swarming: apart from honey production there is probably no other behaviour of bees which varies as much from one year to another.
The progress of this natural tendency which is broadly the result of hereditary conditions, depends on a series of interacting factors: the spring build-up linked to climatic conditions, the strength of the colony, local availability of forage, the beekeeper’s approach and many others. Contrary to what is sometimes said, the characteristics of this desire to swarm cannot be rigorously measured. It is not possible simply to note as a parameter the number of queen cells found in the course of a season. It is more a matter of if the mood, the ”urge“ to swarm is present in a colony. Some colonies gripped by this urge only build a few cells, ten or fifteen, even less. But they are still as much subject to the intoxicating desire to swarm. During this lethargy phase it is commonly known that the colony appears to store up all its resources to preserve them for the future. There is therefore a reduction in foraging, care of the brood and the queen, cessation of comb-building etc. The bees hang motionless. Elimination of the queen is the only way to prevent such colonies from swarming. This can be achieved by the introduction of a viable queen cell or by requeening. In spite of the amount of effort expended these colonies usually waste the early harvest. And what is more they generally fail to achieve the strength required to obtain good results from succeeding foraging expeditions.
It is the case that colonies which are reluctant to swarm prepare queen cells during the swarming period. But they nevertheless continue to work as usual. The nurse bees care for the brood, the queen continues to lay well. It is possible to check the impulse to swarm by destroying these cells. Most of the time it requires no more than two inspections to put a stop to this cell construction and avoid the departure of a swarm in colonies bred for reluctance to swarm.
Here are further indications:
One can only give a mark of ”good“ or ”very good“ to colonies with very little or no sign of swarming. The rating is only really valid in those years when the swarming urge has been widespread. In those years it will be possible to observe a full spread of various kinds of behaviour from which objective observations may be drawn. In years marked by a low propensity to swarm, colonies which present these indications over a long period are to be down-rated. In point of fact such colonies should be excluded from any breeding programmes.
Note that for this characteristic perhaps more than for any other, the situation of the apiary as a whole should be taken into account and also that of other apiaries and of the entire region before drawing conclusions about each particular colony. The swarming urge plays a distinctly lesser role in the regions of the South than in those of the North and in average to high altitude areas.
The reproductive instinct — with the bee the swarming instinct — is a constant of living beings. Suppressing it would be unnatural and probably impossible. The aim will therefore be to obtain colonies which do not have the desire to swarm or in which the swarming urge does not appear. It is essential to be able to control swarming within restricting the queen’s egg-laying, without breaking into or splitting up the brood nest in any way.
This objective has been broadly achieved in colonies of our pure breeding lines even with their daughters by natural fertilization. Crosses however require the strictest controls because of hybrid vigour.
Fertility, the mass of brood which a colony can produce, is the result of the interaction of two main parameters: the egg-laying capacity of the queen and the predisposition of her daughters, the nurse bees, to breeding. The characters of two generations therefore influences this characteristic. This probably explains the differences observed in carrying out crosses in one direction or another.
Fertility together with the viability and longevity of the workers is one of the major features responsible for a colony’s performance. Management of strong colonies is generally easier. They have much more to offer the beekeeper and record higher yields. Unfortunately ultra-high fertility is often accompanied by a diminution of longevity, although this is not always the case (Brother Adam).
At the present time one question has not been fully answered: how do heavily populated colonies resist Varroa infestations? The extent of their brood does not limit the reproduction of the acarine mite. If the infestation is often greater here, these populations appear to tolerate more varroa than weak colonies. Moreover the regenerative capacity of these colonies is distinctly better. The parameter which appears most important is the duration of the presence of brood. It is important that the winter break should be as prolonged as possible.
The surface area occupied by brood should be assessed: the number of frames and its extent on each frame. To obtain the maximum rating for this criterion colonies’ brood should cover in May-June 9 to 10 Dadant frames. This brood nest should only be restricted at this period by very slight deposits of honey. These deposits naturally depend on the harvest. The duration of the maximum extent of the brood nest is also accounted for in the rating. In July therefore the maximum scores previously ascribed should be reassessed.
It is a question of finding a compromise between an adequate fertility rate and a series of other factors: principally longevity, broodnest pattern and varroa tolerance. The latter determine the development and performance of the colonies and display an interactive relationship with fertility. The management of colonies with high fertility levels is generally easier. They offer more to the beekeeper and (as a general rule) register better harvests. In regions of early foraging, consideration should also be given to the time taken by colonies to achieve an adequate fertility level.
The Buckfast bee can be said to be very fertile. Only the Italo-American bee exceeds it but with a shorter longevity. A number of crosses also outdo it on sporadic occasions. Since the various relationships concerning fertility and the problems due to varroa are not yet entirely known future prospects remain to be decided.
Maximum harvests result from the balance of all the elements which contribute to the yield of nectar and/or honeydew through to the storing of finished honey in supers. Included too is an interesting and varied nectar-yielding flora and favorable climatic conditions.
The selective breeder cannot simply bank on productivity itself which is far too complex. It is necessary therefore to rely on the indirect parameters described earlier: disease resistance, longevity, viability, fertility and reluctance to swarm. To these qualities already described may be added others real but hard to define and/or measure. These are diligence or indefatigable zeal, the capacity and speed of discovery (smell and orientation), power of flight and the perfect division of labour within the whole colony (discovery, foraging, comb-building, drying, storing). It is these features which in the end make the difference to the harvest particularly during the summer flow but also during the flows which are continually disrupted by the whims of the weather.
It is essential that the environment and climate are favourable so that the effect on the totality of factors affecting foraging may be reflected in the harvest. It is quite possible to measure harvests precisely. But it is by no means possible to compare them between different apiaries. Even at a distance of some kilometers. The best is to compare each colony with the average obtained in the apiary, yet bearing in mind the fact that in small apiaries disastrous results (by chance) can cause a sharp drop in the average for this apiary. In this case a colony with an effective harvest (compared with the true possibilities for this site) will become a ”super-champion“.
Conversely if one of the apiaries is only populated with excellent colonies, their rating may well merely bring them down to the average because it is the location of the apiary which, by giving a very good average, will be considered excellent.
For the evaluation on the basis of the average by location to be correct it would require between 30 and 40 colonies (representative of the total genetic stock). The most interesting is the average for each genetic group over all locations.
In practice one finds one or two colonies per apiary which stand out with a superior harvest. Those which only obtain a clearly poorer harvest are down-rated and the rest is average. Evaluation is given for each harvest.
Even from an ecological point of view there is nothing against a maximum crop from the bee. The maximum crop results ”from the balanced totality of a large number of factors which encourage productivity“ (Brother Adam) including those concerning nectar-bearing flora and the climate. While the aim of seeking a maximum crop is implicit it should be tempered by the work-time the beekeeper must spend following each colony. The effective yield from the beekeeper’s point of view is indeed the quantity harvested per hour of work. The capacity of a bee farm is undoubtedly limited by the additional work to be done during swarm control. If an exceptional production is due to an extreme level of viability and/or fertility, it will be accompanied by the impulse to swarm at the limit of what may be controlled. This will require hours of painstaking attention out of proportion to the risk, according to the season and despite controls, of setting in motion a ”swarming urge“ at the crucial moment. If the latter cannot be controlled the losses of revenue will be considerable. Of course later on, such colonies which will have been calmed by all these robust interventions, can produce maximum yields at the time of late harvests.
Throughout the whole world the Buckfast bee is classified amongst the most productive of breed lines. This position is confirmed by the fact that the majority of professional beekeepers from every continent have adopted it.
The propensity to link comb with brace wax has its origin in nature. In modern hives it is quite unnecessary. On the contrary it handicaps the work of the beekeeper. This inopportune ”feature“ can be fairly easily eliminated through traditional selection. But it returns just as quickly following crossing or non-directed natural fertilization. One should not be misled. Colonies busy with harvesting and short of room will occupy, build up and fill with honey every free space. One should not confuse this emergency building with the need to create connecting links virtually everywhere.
This evaluation cannot be properly made during a honey flow. It should instead be carried out during a weak flow or between flows. Naturally the maximum rating is given to colonies which even during a heavy flow establish hardly any brace comb on the queen excluder, between the supers and on the crown board.
On the other hand colonies are down-rated which despite adequate space and the presence of construction wax unnecessarily build up the queen excluder and the spaces between supers and frames.
There should be colonies which in appropriate harvest conditions do not build any brace comb neither on the queen excluder nor between supers nor between frames. This makes it possible to work not only quickly but pleasantly and in an ethical way thereby virtually eliminating crushed bees, a consequence as objectionable as it is harmful.
The Buckfast line is the only race of bees for which a selection programme has been realized which takes account of this characteristic.
Everyone knows that propolis acts as an antibacterial agent within the colony. A certain quantity is required to plug all the inaccessible parts of the hive which cannot be checked but also to regularly ”sterilize“ the whole structure. This is probably one of the reasons that impel the bees to become long-stayers, to retain the same habitat over several years.
However because of its sticky and adhesive consistency, this propolis especially when it is present in quantity is a hindrance when inspecting colonies. What is more it is difficult to get rid of propolis stains on clothing. Bees’ behaviour in harvesting propolis varies enormously. Some varieties such as the Anatolian and Caucasian harvest great quantities throughout the year. Others like the black bee harvest a great deal but particularly at the end of the season. The Carniolan bee uses pure propolis during the year but a mixture of propolis and wax in autumn.
Colonies which accumulate propolis in quantity before wintering (August) have a low score. In September/October when attending to feeders this is a good opportunity to conduct an objective inspection of all colonies.
Suppression of propolis seeking would be artificial and probably harmful to colonies. In the spring ideal colonies would eliminate surplus propolis accumulated along the internal walls. A kind of cleaning as it were.
The Buckfast race is currently the only line of bees known for which a selection programme has been realized which takes account of this characteristic.
We carry out replacement of the queens in our production colonies either in September/October or in March/April. However all the colonies rated above average retain their queen for over-wintering. The progress of this over-wintering and the succeeding spring build-up are important selection criteria. After winter in nuclei on 3 frames of brood and one of stores only the best of these queens sill be placed in the breeding apiary. They will be in retirement there as breeding mothers.
As all our hives are identical they are brought to the same weight towards the end of September. In January we carry out a check on bee mortality.
Of course candidates for reproduction are examined with the closest attention. In the Spring, the level of build-up is estimated by comparing the strength of the colonies.
Colonies which indulge themselves with an exaggerated winter brood are wasting, as everyone knows, their ”colony’s substance“: by which we mean not only the bees themselves but also their store of pollen and honey. In the most favourable cases this winter brood will make for a strong colony after wintering but with a shortage of stores. In critical cases there follows a series of possible diseases not the least of which is nosema. (see the chapter Viability of bees).
A cessation of winter egg-laying for as long as possible with a consequential saving of the ”substance of the colony“ throughout this period of virtually complete inactivity. But colonies are required to be ready for the first honey crop (about the end of April in our region) and this without any stimulation or reinforcement.
Contrary to a great many different reports the pure Buckfast bee which we breed tends to cease egg-laying early. From mid-October the majority of colonies no longer have any. However all the pure races including the Buckfast start up their brood again from mid-January. The crosses on the other hand behave differently. It should not however be concluded that the hybrid vigour effect of crosses always leads to an increase of winter brood. Currently our crosses of Buckfast with the meda (Iranian) yet again confirms this.
Normally the only winter losses are only due to orphan colonies.
The selection of a bee more tolerant of varroa is still at an elementary stage. Year after year fundamental research on this parasite brings us new knowledge. There have been widespread efforts to set up work groups to promote breeding of bees with tolerance of varroa. The Gemeinschaft der Europäischen Buckfastimker e.V. has instigated various projects. the ”Primorski“ project will make it necessary to undertake a more extensive form of evaluation. The breeders’ association will take responsibility for this.
So far the number of varroa mites have been assessed by their mortality rate during the August treatment for acarine. Colonies were graded by apiary to take into account the secondary infestations due to local conditions (presence in the environment of non-treated colonies).
In addition potential reproductive colonies undergo the test of brood frozen or killed with a pin. Assessment was made of the speed with which they disposed of this dead brood.
Time will tell if new indirect parameters could be utilized.
I find interesting those colonies which despite the presence of a great deal of brood are only subjected to a weak or moderate attack as well as the colonies which in spite of a major investment of varroa mites show no signs of secondary viral infections neither on the bees nor at brood level.
There is no doubt. We have to achieve productive colonies which maintain themselves without the slightest treatment or manipulation.
One should recognise it and not be misled: no sign of any real resistance is in sight! And this applies to every race of bees used in Europe. One can but hope. The only light at the end of the tunnel: at the time of the varroa invasion at the beginning of the 80’s, treatment measures to save the colonies were necessary from the middle of July. Today no damage is evident before mid-August even in places where the proximity of untreated colonies greatly increases the varroa pressure.
With these ten points we hope to have a made a contribution to a better understanding of what is meant by selection in beekeeping. However differences between theory and practice are unavoidable. We have to accept this. Selection in bee colonies is complex and frequently obscure to the uninitiated. The real problem arises from the fact that in practice it has been found impossible to define a series of valid norms. The more one tries to understand the relationships the more complicated and confusing the matter becomes. This is so even as in this case one puts on one side the genetic and biological aspects peculiar to bee breeding.
One of the observations put to me by Dr Job Van Praagh is to the effect that one could stop taking notes and collating scores for weak colonies. This colony weakness would be automatically eliminated as a result of positive conclusions drawn from elsewhere. This is true and we have operated in this way for years. But colony weakness must also be understood and it is as easy to make a note of sizes as it is to set them aside.
A breeding programme carried out on the base of appropriate selection leads always and above all to understanding of the phenotype and the living conditions of the different colonies (and breed lines) which one seeks to increase. Of course this supposes that the entire stock is worked and evaluated regularly and logically by one and the same person. But there are limits to human capacities for work and observation. These limits are the barriers against which each correctly managed breeding project should halt.
This should be sufficient unto the day.
Abeilles & Cie, the CARI asbl
No 90, october 2002, 9-13, et
No 91, december 2002, p??
Original : Auswertung von Bienenvölkern
Möglichkeiten und Grenzen der Zuchtbetriebe.
In: Der Buckfastimker
Nr 10(Heft 4), 2001 Seite 6-22.
The discussions forum of the buckfast bee-keepers
LU-9361 - Brandenbourg, Lux.
22th May 2001
web : http://www.apisjungel.lu