Climate and Environmental Adaptation

Climate and environmental adaptation is the way honey bee races and local ecotypes have become tuned, over thousands of years, to the winter, heat, drought and flowering calendar of the region where they live. This adaptation shows in the size of the winter cluster, in when brood rearing starts and stops, and in the response to dearth. For the beekeeper the practical upshot is simple: a bee adapted to its region needs less feeding, comes through the winter with fewer losses and catches the forage on time.

How do honey bees adapt to climate?

The honey bee lives naturally over a very wide area, from the tropical forests of Africa to the short summers of Scandinavia. What makes this possible is that it is not individual bees but the colony as a whole that adapts. The colony manages heat, population and food stores together. Most of the difference between races lies in how this management is "tuned".

• Winter cluster and consumption: Bees from cold regions go into winter with a smaller but tighter cluster and use their stores thriftily.
• Timing of brood rearing: In regions with a short season, spring build-up is fast; in regions with a long season it is more measured.
• Response to a break in forage: Bees from dry regions cut back brood rearing quickly when nectar stops and conserve their stores.
• Flight temperature: Bees from cool, mountainous regions are reported to go out foraging at lower temperatures and in overcast weather.
• Tongue length and body structure: These vary from race to race according to the region's flower structure and climate; the Caucasian bee has the longest tongue.

Adapting to a cold climate: how does wintering work?

When the weather turns cold, the bees form a winter cluster between the combs. Bees in the outer shell of the cluster pack tightly to retain heat, while bees inside produce heat by shivering their muscles. The fuel for heat production is honey; that is why wintering success depends largely on the amount of stores and how close they are to the cluster.

Bees from regions with long, harsh winters (for example the European dark bee, the Carniolan bee and highland ecotypes) stop brood rearing early in autumn, go into winter with long-lived winter bees and consume little. A line from a mild region that stops brood rearing late in autumn, on the other hand, can run out of stores on a cold plateau.

Adapting to a hot, dry climate

In hot regions the real test is the summer dearth. Populations such as the Syrian bee and the bees of Anatolia's dry interior cut back brood rearing in the hottest months and balance their population against their stores. To regulate the temperature inside the hive, the bees carry water, ventilate by fanning their wings, and crowded colonies "beard" in front of the entrance.

A drought-adapted bee taken to a region with abundant forage may not use its full potential; conversely, a line used to uninterrupted forage may keep rearing brood all summer in a dry region and use up its stores.

Why does the local ecotype matter?

Even within a race there are differences from region to region. Türkiye is one of the best examples of this: the Anatolian bee has different ecotypes in different regions. A well-known example is the Muğla ecotype: it has adapted to the mild winters of the Aegean coast and to the pine honey flow in autumn; the queen keeps laying in autumn too, building up the population for the pine honey period.

When the same bee is taken to the long, cold winter of Central Anatolia, its late stop to brood rearing in autumn can turn into a problem with stores and wintering. The Caucasian bee, on the other hand, is adapted to the short, intense highland season of north-eastern Anatolia and to cool, rainy weather.

What does poor adaptation look like in the hive?

The signs of a bee that does not suit the region are often noticed a season later:

• Brood not stopping late in autumn: Stores dwindle fast and winter feeding increases. Because the broodless period is shorter, Varroa also reproduces for longer.
• Growth when there is no forage: A fast-developing line in a region without early forage grows for nothing, eats its stores and starts swarm preparations.
• Missing the forage: A late-developing line fails to reach a big enough forager population for an early, short main flow.
• Collapse in the summer dearth: A bee used to uninterrupted forage keeps rearing brood in a dry summer and weakens.

How is climate change affecting bees?

Local adaptation rests on a past in which the climate was relatively stable. As temperature and rainfall patterns change, this balance can break down:

• Flowering is shifting: Plants respond mainly to temperature; colony development, however, depends on a combination of day length and temperature. When the two shift at different rates, the forage can open and finish before the colony is ready.
• Mild autumns and winters: These extend the brood season; the broodless period narrows and timing the winter Varroa treatment becomes harder.
• Drought and heat waves: These reduce nectar secretion; the summer dearth lengthens.
• Sudden cold and frost: In a colony that has built up early, a cluster that cannot cover the brood can lose brood to the cold.

How can a beekeeper make use of local adaptation? Step by step

1. Work with a local line: A queen selected in your region is the cheapest and most lasting advantage.
2. Keep your own calendar: Note the start and end of flowering of important forage plants year by year.
3. Use a hive scale: The daily change in weight shows whether the forage is really flowing.
4. Go into winter with stores: Check hive weight and honey frames in autumn; if they are insufficient, feed in time.
5. Provide water and shade: In hot regions keep clean water near the apiary; choose a spot that gets afternoon shade.
6. If you bring in queens from another region, try a few: Monitor their behaviour in wintering and in the summer dearth for at least a year.

Why should genetic diversity be protected?

Local bee populations are a gene pool carrying traits of climate adaptation. Uncontrolled imports and careless crossbreeding dilute this pool and reduce the capacity to adapt that may be needed in a changing climate. That is why, in Türkiye, the establishment of a gene centre for the Caucasian bee in Artvin and Ardahan and the registration of local ecotypes are important.