Australian bees ‘head bang’ for pollen

By Amelia Caddy 17 December 2015
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We’re all familiar with the sight of a bee burying its head in a flower, but what actually happens in those moments before it re-emerges, covered in pollen?

SCIENTISTS HAVE DISCOVERED that a species of Australian native bee uses an extreme form of ‘head banging’ to collect pollen from flowers.

The rapid tapping movement, which was videoed occurring at a brain-numbing 350 times per second, causes vibrations that shake pollen out of a flower’s anther – where pollen is produced.

“The anther cone is like a salt and pepper shaker – it needs to be shaken to get the pollen out. It can be shaken by wind and a little bit of pollen comes out, but if it’s shaken at the right frequency, all the pollen comes out,” said Dr Katja Hogendoorn, a bee specialist from the University of Adelaide.

Australian bees faster, more effective than bumblebees

Katja’s colleague, Callin Switzer from Harvard University, recorded the audio frequency and length of the buzzing of Australian blue-banded bees (Amegilla murrayensis) and North American bumblebees (Bombus impatiens) as they visited flowers.

By analysing the recordings, they found the Australian bee’s method was not only faster than that of the bumblebee, but also more effective.

“What happens is that, because the shaking reaches the optimum frequency, [the anther] releases more of the pollen in one go,” said Katja.

The head-banging behaviour has never been observed in any other bee species. Bumblebees use a similar but less effective method to loosen the pollen, in which they grasp the flowers and tense their wing muscles, causing the flower and anther to vibrate at about 250 times per second.

Head banging discovery important for Australian farmers

According to Katja, the discovery could help Australian farmers achieve better crop pollination.

“We have already shown that blue-banded bees can pollinate tomate. This new finding suggests that blue-banded bees could also be very efficient pollinators, needing fewer bees per hectare,” she said.

The use of vibrations to shake free pollen is called ‘buzz pollination’. While scientists knew Australian blue-banded bees performed buzz pollination, it was believed they employed the same method as bumblebees.

About 8 per cent of the world’s flowering plants need to be buzz-pollinated in order to reproduce, including tomatoes, blueberries, eggplants and chillies.

The common western honey bee cannot buzz-pollinate, while the bumblebee is considered an invasive and potentially harmful species in Australia, making the efficient native blue-banded bee valuable to Australian farmers.

The research will be published in an upcoming edition of the journal Arthropod –Plant Interactions.


Video credit: Callin Switzer, Harvard University, via RMIT University, Melbourne