Bees use patterns – not just colors – to find flowers

Honeybees rely heavily on flower patterns – not just colours – when searching for food, new research shows.

A team led by the University of Exeter tested bee behaviour and built bee's-eye-view simulations to work out how they see flowers.

Honeybees have low-resolution vision (about 100 times lower than human vision), so they can only see a flower's pattern clearly when they are within few centimetres.

However, the new study shows bees can very effectively distinguish between different flowers by using a combination of colour and pattern.

In a series of tests, bees rarely ignored pattern – suggesting colour alone does not lead them to flowers.

This may help to explain why some colours that are visible to bees are rarely produced by flowers in nature.

"We analysed a large amount of data on plants and bee behaviour," said Professor Natalie Hempel de Ibarra, from Exeter's Centre for Research in Animal Behaviour.

"By training and testing bees using artificial patterns of shape and colour, we found they relied flexibly on their ability to see both of these elements.

"Showing how insects see colour and learn colour patterns is important to understand how pollinators may, or may not, create evolutionary 'pressures' on the colours and patterns that flowers have evolved.

"Our findings suggest that flowers don't need to evolve too many different petal colours, because they can use patterns to diversify their displays so bees can tell them apart from other flowers."

One consistent feature identified in the study is that the outside edges of flowers usually contrast strongly with the plant's foliage – while the centre of the flower does not have such a strong contrast with the foliage colour.

This could help bees quickly identify colour differences and navigate to flowers.

While flowers may be beautiful to humans, Professor Hempel de Ibarra stressed that understanding more about bees – and the threats they face – meant we need to see the world "through the eyes of a bee and the mind of a bee".

The research, by a team including the Free University of Berlin and the University of Auckland, was funded by the Biotechnology and Biological Sciences Research Council (BBSRC).

The paper is entitled: "The role of colour patterns for the recognition of flowers by bees."

It is published in a special issue of the journal Philosophical Transactions of the Royal Society B, edited by Professor Hempel de Ibarra, alongside Dr Ayse Yilmaz and Professor Almut Kelber, both from Lund University, entitled: "Understanding colour vision: molecular, physiological, neuronal and behavioural studies in Arthropods."

It highlights the latest advances in research that unravels the diversity of colour-vision systems found in invertebrates, demonstrating many interesting adaptations to their different life styles and to their diurnal and nocturnal habitats.