Bumblebees can identify pollen quality based on floral features like petal colour in an attempt to pick the right flowers, according to a new study by the University of Exeter.

Until now, bees' ability to form associative relationships between physical features of a flower and the pollen quality remained unclear.

For the study, researchers tested bumblebee foragers under controlled conditions to determine whether they learn about flowers during pollen collection or not. In the experiments, they manipulated the quality of pollen by diluting the samples. The researchers presented four different coloured discs containing stronger and less diluted pollen to record preferences and change of preferences over time. The researchers only let the bees smell and see the pollen rather than probing it.

The researchers found that bumblebees can evaluate pollen samples and can quickly form preferences for a particular type of pollen. The pollen foraging behaviour involves learning and individual decision-making that allows bees to quickly decide which flowers provide the most nutritious pollen for nurturing their young.

"There is still very little known about how bees decide which flowers to visit for pollen collection. Easily learning floral features based on pollen rewards, without needing any nectar rewards, is a fast and effective way to recognise those flower species which bees have previously experienced to be the best ones," Dr Natalie Hempel de Ibarra, Senior Lecturer in Neuroethology, said in a statement.

Dr Elizabeth Nicholls, a Post Doctoral Research Fellow at the University of Sussex, said that since bumblebees don't eat pollen while foraging, the researchers were intrigued to know how they are able to judge the quality.

"Here we've shown that they are able to detect differences in pollen, even before landing, which means they may be able to tell, just from the colour of the petals, which flowers are worth visiting,"

The finding is published in the Journal of Experimental Biology.