Dear friends

Propolis - the original firewall

It is only now that the beekeeper looking after the honey bee colonies situated on the roof of Notre Dame cathedral in Paris – which suffered catastrophic fire last April – has been able to visit the bees and confirm that all are fine, though their wooden hives would surely have burnt if they had been near the flames. In the recent fires across huge areas of South and East Australia, forests, mammals and bees have been destroyed. This destruction of natural habitat will have severe impact for Australian beekeepers who harvest 75% of their honey from forests. Our friends at Beechworth Honey were helping beekeepers to relocate hives to safe areas, away from fire risk, and Australia’s charity for bees, the Wheen Bee Foundation is now supporting beekeepers with livelihoods at risk. You can support them too: at https://www.wheenbeefoundation.org.au/.

The bees in Australia are Apis mellifera of European origin, and fires probably did not feature much in their evolutionary history. What about honey bees that have evolved in areas where fire is commonplace? Researchers from South Africa and Germany* provided a wonderful insight when they published this new understanding about the Cape honey bee, Apis mellifera capensis, which is endemic to South Africa’s Western and Eastern Cape Provinces. The Cape Fynbos vegetation is adapted to fires which happen naturally every 15 - 25 years, and cover vast areas – with few nectar-producing plants surviving. For example, a wild fire in the Cederberg area burned for six days and covered 13,500 ha, turning the entire region into a temporary wasteland.

This harsh physical environment determines the nesting behaviour of the Cape bee: analysis of 37 wild honey bee nests revealed that 78% occurred under boulders or in clefts in rocks, 11% in the ground, 8% in tree cavities, and 3% within shrubs. Analysis of 17 of these nests following a fire within the park revealed that the propolis walls materially protected the nests and retarded the fire, with all these colonies surviving. The bees responded to the smoke by imbibing honey and retreating to the furthest recess of their nest cavity. The bees were required to utilise this honey for about three weeks after which fire-loving plants appeared and began to flower. The bees used considerable resources to construct the propolis walls, which ranged in thickness from 1.5 to 40.0 mm (mean 5.0 mm).

The researchers concluded that the prolific use of propolis insulates the bees’ nest from extremes of temperature and humidity, restricts entry, camouflages the nest, and acts as an effective barrier to protect the bees from fire.

*Geoff Tribe, Jürgen Tautz, Karin Sternberg & Jenny Cullinan, Firewalls in bee nests – survival value of propolis walls of wild Cape honeybee (Apis mellifera capensis). Sci Nat (2017) 104: 29 DOI 10.1007/s00114-017-1449-5

Nicola Bradbear Director, Bees for Development