A new future for the dark bee?

We witness an increasing interest in the indigenous European dark bee (Apis mellifera mellifera), which is hardly surprising for it fits perfectly in the modern approach to beekeeping, in which conservation issues are so important. This subspecies of the honeybee is seriously threatened through unlimited spreading of other subspecies (carnica!) and artificial races (Buckfast!) in the past century.

From the Atlantic Ocean to the Ural Mountains, from the Pyrenees to Finland, this robust, vital and modest bee has settled in virtually every ecological niche and adapted to all climate changes since the ice ages.

The dark bee can be distinguished from other bees clearly. First of all by her dark appearance, the broad and rounded abdomen with narrow felt bands and the long dark hairs. She can also be typified by her characteristic wing venation.

Selection characteristics

Which characteristics can be used as selection criteria? There is a more or less general agreement about body characteristics. Their margins for the purebred dark bee have been established fairly clearly. However, it is a challenge to select for body characteristics with a fair degree of confidence in a hybridised population. The reason for this is that, for example, divergent combinations of wing venation characteristics cannot always be interpreted correctly, leading to false positive or false negative results.

Behaviour

The way in which we observe behaviour strongly influences our judgement. It is difficult to measure behaviour in an objective manner. The observer may have a preference for a certain type of behaviour and, for that reason, prefers colonies that answer this characteristic. The dark bee is not overly aggressive, but her hybrids are by all means, just as hybrids of other ‘purebred’ subspecies, incidentally. This is a persistent misunderstanding among beekeepers. Also, the number of interventions in a hive and the way we carry these out has a big influence on the behaviour of a colony.

The behaviour of the dark bee is often judged quite variably. Small wonder, for variations in the environment (climate, geography) have a big influence on this. Behaviour depends on ecological conditions. Phenotypic differences may have the same genetic basis. In other words, the same genes may lead to quite some phenotypic variation.

The dark bee reacts strongly to changes in the environment and adapts her brood nest accordingly. During nectar flow periods brood production is never abundant and during dearth periods the queen even completely stops laying eggs. Because of this, brood care normally is excellent and workers are long-lived, in summer up to 10 weeks. As a result of the relatively small population size spring development of the colony lags behind other subspecies: the dark bee is first and foremost a bee for summer and autumn nectar flows. At the same time her longevity and small brood nest lead to a relative abundance of foragers. Therefore, the dark bee can render excellent pollination services in spring, also because of her strong focus on pollen gathering to replenish pollen stocks in the colony.

All in all, we are dealing with a cautious bee.

Adaptation

Over the centuries, every bee race has adapted up to a certain point to climate, flora and other characteristics of the environment where the race is indigenous. This implies that a colony will not thrive equally well when it is transferred to a different environment. For example, races from the Mediterranean region are adapted to a warm climate with a nectar supply that is guaranteed for the better part of the year. This condition renders colonies wasteful in brood production and food consumption. When they are transferred to a colder climate they often do not manage to collect sufficient honey stores to survive long winters.

The environment has a strong influence on the behaviour of a colony. However, we can compensate for this behaviour by our interventions: feeding colonies, making divisions, requeening. The annual brood cycle depends on springtime development, a brood pause as a result of swarming and the moment of cessation of egg laying. The brood cycle is also influenced by breaking queen cells, producing artificial swarms and extracting honey. Therefore, the pattern of brood production, though being a characteristic of the colony, is influenced by the beekeeper.

Characteristics of the dark bee

The dark bee flies at temperatures as low as 5.5 °C. Because of her dark appearance she warms up faster than other subspecies and races. As a consequence, she collects food under colder conditions and at earlier and later moments of the day. The nuptial flight of the virgin queens can also occur during bad wheather spells in the immediate surroundings of the apiary provided the minimum temperature is higher than 9 °C.

The tongue us slightly shorter (5.8-6.2 mm) than with other subspecies. As a result, the dark bee cannot collect certain types of nectar and pollen. At the same time, the indigenous flora is probably adapted to this shorter tongue length.

The dark bee has a higher flight range and bigger load capacity than other subspecies. This would be an advantage during periods without a major honey flow. She is very economic with available food stores. This means she maintains a low temperature in the winter cluster and starts brooding relatively late in spring. During the brood season she maintains relatively small brood nests, thus depending less on a steady supply of nectar and pollen. As mentioned, even during honey flows, egg laying never is abundant. During periods of absence of a honey flow the queen may even cease egg laying altogether. At night and during periods of low nectar availability the brood nest temperature may sink considerably. Differences of 17 °C between the minimum and maximum are possible. In this way food reserves are consumed less, but the brood becomes more susceptible to chalk brood outbreaks.

The dark bee focuses strongly on collecting pollen rather than nectar and maintains a pollen store sufficient for 2 to 3 weeks. In combination with the small brood nest this results in long-lived worker bees, up to 10 weeks in summer. The ratio foragers – domestic bees is high, often resulting in unexpectedly high honey yields for relatively small colonies. At the same time, this ratio may result in brood becoming chilled, with ensuing chalk brood.

Selection for chalk brood resistance is key in order to maintain the ratio foragers – domestic bees within reasonable limits and to maintain a brood nest of sufficient size.

Because of its longevity a dark bee colony is capable of maintaining the natural population structure, in which all tasks, whether inside or outside the hive, will be executed in good harmony.

There is only a limited risk of a surplus of young bees – a necessary condition for swarming. In skep beekeeping, which was practised with the dark bee, swarming was considered favourable in order to have a maximum of colonies for the heather honey crop. Space was limited in the skeps, which is why swarming occurred early in the season. If enough space is given to the queen for laying eggs, the swarming tendency of the black bee is not higher than in other subspecies.

The brood nest of the black bee is compact. Pollen is stored right around the brood nest, often in an uninterrupted circle, with the nectar stored all around. Honey cells are capped with convex white cappings, as a result of air being trapped between the honey and the capping.

The small size of the overwintering colony has a negative impact on temperature loss of the winter cluster and thus on food consumption. At the same time, winter clusters of the dark bee are very compact, reducing heat loss. All in all, dark bees overwinter well.

Dark bees have a pronounced tendency to run across the frames, up to a point where they even form a small cluster clinging to the frame. A disadvanage of this behaviour is that it renders finding the queen harder. So care must be taken when taking the frames out of the hive.

The dark bee handles Varroa attacks very well. She survives these even without chemical treatments, as has been proven over the past years by members of De Duurzame Bij (‘The Sustainable Bee’). For more information see www.duurzamebij.nl (in Dutch).