The honey bee lives across a very wide geography. What makes that possible is that its subspecies have adapted to the climates they live in.

Where adaptation shows

• Size of the winter cluster: Cold-climate subspecies form a small cluster and consume little
• Rate of spring build-up: Fast where the season is short, more measured where it is long
• Response to a break in forage: Bees of arid regions cut brood rearing quickly
• Flight temperature: Cool-climate bees fly at lower temperatures
• Tongue length: Varies with the flower structure of the region

Why local adaptation matters

A subspecies has been selected for its own region's forage calendar and winter.

An imported line that looks more productive in a catalogue may fall behind in local conditions: it misses the flow, consumes heavily in winter, or rears brood at the wrong time.

Concrete examples of mismatch

• A line adapted to a long season stops brood rearing late in a region with a short winter; stores run down and the Varroa cycle is extended
• A fast-building line grows for nothing and swarms in a region with no early flow
• A line adapted to arid conditions does not use its potential where forage is abundant

The effect of climate change

This adaptation assumes a stable climate. As the flowering calendar shifts, the fit breaks down.

• Colony development runs on a combination of day length and temperature; plants respond mainly to temperature
• When the two shift at different rates the flow opens and closes before the colony is ready
• A warm autumn extends the brood season; the broodless period narrows and the timing of Varroa treatment is disrupted

How the beekeeper adapts

• Follow the colony, not the calendar. The actual state of the forage and the brood is more reliable than a date
• Keep your own records. Write down when flowering began in your area each year
• Work with local lines. Adaptation is the cheapest advantage there is
• Use a scale. Weight tells you whether there is really a flow

The value of genetic diversity

Local subspecies are a pool of adaptation. Uncontrolled importing and hybridisation dilute that pool and reduce the capacity to adapt as the climate changes.