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School β€Ί Bees β€Ί Ages 15–16

Pollination, colonies and the waggle dance

Pollination as plant reproduction, how a honeybee colony shares its work, the chemistry of turning nectar into honey, decoding the waggle dance with a calibration graph, and the uncertain numbers behind pollinator value.

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Pollination is the transfer of pollen from anther to stigma, which allows fertilisation and seed formation. Animal-pollinated plants reward visitors with nectar and pollen; bees and flowering plants have co-evolved for over 100 million years.[1][4]

A honeybee colony is divided into castes: one reproductive queen, non-reproductive female workers whose tasks change with age, and male drones. Workers keep the brood at about 34 Β°C. When a colony swarms, the queen leaves with up to two thirds of the workers; a swarm holds about 10,000 workers.[5][6]

To make honey, hive bees use enzymes to break sucrose in nectar into simpler sugars, then fan the stored liquid until the water content falls from 50–70% to about 18–20%. One pound (about 0.45 kg) of honey takes visits to about 2 million flowers.[7]

Foragers communicate food sources by dancing. A round dance means food within about 100 m, with no direction. In the waggle dance (food beyond about 200 m), the angle of the waggle run gives the direction relative to the sun, and the duration of the run gives the distance. Recruits follow about 6–8 dance cycles and average them.[6]

Estimates of pollinator value depend on what is measured: about 84% of EU crops depend on insect pollination, while about 35% of the world's food crops depend on animal pollinators, and pollinators add an estimated $235 billion a year to global crop value.[1][2]

Pollinators are declining. Suggested causes include climate change, habitat loss and degradation, and light pollution; in the U.S. more than 70 pollinator species are listed as endangered or threatened.[1][2]

Try it: Decoding the waggle dance

⏱ 50 minutes

You need

  • Graph paper or a spreadsheet
  • Stopwatches
  • Large protractor and chalk or masking tape
  • Map of the school grounds with a scale
  • Cards showing a hidden 'food source' (direction and distance)

Safety

Keep the walking area clear of bags and chairs. Do not walk backwards near steps or furniture.

What to do

  1. Plot the calibration data: waggle-run time (s) on the x-axis against distance (m) on the y-axis: 0.5 s β†’ 200 m, 1.0 s β†’ 800 m, 1.5 s β†’ 1,400 m, 2.0 s β†’ 2,000 m, 3.0 s β†’ 3,200 m.
  2. Draw the line of best fit and find its gradient and intercept. Write the equation in the form d = mΒ·t + c.
  3. In pairs, one student is the 'scout'. Using a card, they walk a straight waggle run on a vertical wall chart (or on the floor, with 'up' taped as the direction of the sun) at the card's angle, for a time chosen from the graph.
  4. The 'recruits' time each waggle run with a stopwatch and measure its angle with the protractor. Repeat for 6 runs and take the mean.
  5. Use your equation to convert the mean time into a distance, and the angle into a direction relative to the sun.
  6. Compare with the card. Work out the percentage error and discuss its sources.
What happens, and why?

In the waggle dance, the angle of the run codes the direction of the food relative to the sun, and the duration of the run codes the distance. The calibration values fit a straight line closely (about d = 1200Β·t βˆ’ 400, with d in metres and t in seconds). Human reaction time makes single timings uncertain; averaging several runs reduces random error, as recruit bees do by following 6–8 cycles.[6]

Play: Round dance or waggle dance?

Which dance would a honeybee forager do?

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Quiz

Other ages: Ages 6–7 Β· Ages 10–11