Practical beekeeping – how to foster self-healing

Wolfgang Ritter, CVUA-Freiburg, Am Moosweiher 2, D 79108 Freiburg, Germany

Keywords: American foulbrood, chalkbrood, European foulbrood, hygienic behaviour, sacbrood, Varroa

The fourth in the series from Dr Wolfang Ritter offering advice for Good Beekeeping Practice to ensure healthy honey bees.

How to support brood control by workers

In brood rearing, a honey bee colony not only balances the removal of old and ill bees, it also influences the total number of bees, ie the weight of the colony. To ensure that the colony consists of resistant and long-living bees, only healthy brood should be reared. Therefore, bees constantly inspect their brood: ill parts are removed, healthy parts are maintained and eventually open cells are sealed again. This hygienic behaviour by the bees is part of the self-healing capacity of the colony.

This self-healing capacity has been employed for some time in bee breeding to select Varroa tolerant bees. However, depending on the type of brood disease, the requirements concerning hygienic behaviour are quite different: for example with the Varroa mite, it is less important when the bees inspect the cells. However foulbrood, chalkbrood and sacbrood can be controlled only if they are recognised by the bees before the brood is infected. Otherwise the disease is spread through the colony anyd matters get worse.

Genetics decide

The Alpha and Omega of hygienic behaviour is the genetic predisposition of the honey bee colony. When brood in nucleus colonies with queens of a certain breeding series, or of the same year, becomes ill – chalkbrood and sacbrood mostly appear first – and consequent requeening is the only solution. But in most cases it is more difficult to judge and decide. Quite a lot of management conditions and interventions by the beekeeper influence hygienic behaviour.

In the Varroa tolerant bee colonies observed by Yves le Conte, the bees keep cells with pupae open in order to kill the Varroa mite offspring. The colonies from which this comb originates have survived for seven years without treatment – at Avignon in France

PHOTO © YVES LE CONTE

When inspecting colonies pay special attention to irregularly occupied brood cells

PHOTO © SCHWENKEL

Food stimulates cleaning up

When bees gather aqueous nectar or honeydew, they have to empty any available cell for interim storage. Many bees work through the cells, with crowds of inspecting and cleaning bees on their way to remove everything objectionable. Especially obstinate brood diseases like chalkbrood and sacbrood can be made to disappear this way. If you cannot offer adequate forage for your bees you should feed them with a thin sugar or, even better, a thin honey solution. You can also spray the solution on to the combs to instantly stimulate hygienic behaviour.

Alleviation of infection pressure

If and how quickly the bee colony can heal itself depends mainly on the scale of cleaning activities. Here the beekeeper’s support is required. It is recommended that combs with predominantly ill brood are melted or disposed of. How many combs should be removed depends mainly on the colony’s condition and the season. A strong colony will quickly recover from the loss of part of its brood, especially during periods of growth. You can also take a more radical decision and remove all combs. Then the open artificial swarm allows sanitation even in the case of American foulbrood.

Adaption of space to colony strength

Hygienic behaviour is not restricted to just the brood, but applies to the whole nest. Bees busy cleaning other parts of the nest are not available in the brood area which is the place most at risk. Mouldy combs at the periphery are an alarm signal indicating that the colony is overcharged. Therefore, the space should always be adapted to the colony strength. In some hives with combs in one box - for example in top-bar hives - the brood nest can be defined quite flexibly by a division board. Multiple-storey hives require some caution when the brood nest is expanded or contracted. Only after the bees have completely occupied the available space should you add supers.

On the comb, you can see ill brood below mainly healthy brood

PHOTO © RITTER

Section on the left: ill brood is infested with European foulbrood

PHOTO © RITTER

Section on the right: brood with open cappings

PHOTO © RITTER

Avoid destroying the brood nest

The brood nest is the heart (the core) of the honey bee colony. The bees build it conforming to their colony strength, their requirements and nutritional needs. This is the result of evolution and their development over millions of years. The beekeeper must consider any manipulation very carefully. Best of all is to avoid manipulation because the destruction of the nest arrangement always create stress for the bee colony. By moving brood combs up to create acceptance of an added super, you are destroying the structure of the brood nest that is optimised for optimal internal thermoregulation. You must avoid extending the brood nest by placing combs or comb foundations between brood combs. All these measures create unnecessary stress for the colonies. When bee density is sufficient, respective nectar stores push the brood downwards and widen the brood nest.

BfD acknowledges www.diebiene.de as the original source of this article

HOW TO DO

Adapting the space to colony strength

Brood nest contraction in spring management

Reduce the brood space of colonies that are not occupying the whole hive, especially during spring management.

• Remove combs at the periphery, especially mouldy ones

• Replace fouled combs

• Remove supers with combs that are not occupied.

Best time for brood nest extension

The time to extend the brood nest should not be determined by the calendar or the outer appearance: I keep only strong colonies. The decision should be taken colony by colony, according to the following criteria:

• All bee ways are occupied by bees up to the hive wall

• The lower and probably also the upper parts of the bars of the frame are covered with bees

• Except for combs at the periphery, all combs are almost completely occupied by bee brood

• On two to three combs older emerging brood can be found.

How to extend

The space is extended above, not below, because the combs below are accepted less easily, and because the bees are more active in the upper part near the food wreath (food stores near to brood). If a single super is used, the additional space serves to extend the brood space, whereas in cases of double supers the additional space is left as a honey chamber. Filling it with division boards and comb foundations mostly produces heavy combs that are difficult to handle. Depending on the management scheme, the super on top can be equipped with:

• One third of drawn out combs, and at each of the left and the right sides, one third of frames with foundation

• Frames with foundation

• Frames fitted with starter strips of foundation (depending on the colony’s mood a lot of drone brood could develop)

• Empty frames to enable bees to build comb as Varroa catchers in the second super Spraying the combs with honey water can accelerate the occupation of the new space.

Contraction for wintering

When preparing honey bee colonies for winter, the available space should always correspond to the colony strength and the need for winter honey stores. To facilitate successful overwintering, the colonies should occupy at least eight Langstroth frames or seven Dadant frames.

• Reduce the volume of weaker colonies (for example to one brood box) or unite them

• The contraction of strong colonies to one brood box accelerates the removal of ill bees

• Replace rotten combs and combs that have been used several times for brood.

Checklist for Good Beekeeping Practice

Weak colonies are contracted YES/NO

Bees completely occupy the brood chamber YES/NO

Colonies are expanded only when the bees occupy the whole available space YES/NO

Colonies are not expanded to avoid swarming YES/NO

Disturbance of the brood nest is kept to a minimum YES/NO

Forage is offered to the colonies throughout the year YES/NO

Combs containing mainly ill brood are removed YES/NO