Wild bees visit different flowers to get a varied diet

Bees visit different flowers to keep their diet balanced

In the same way that us humans try to eat a balanced diet, it seems that bees need to do the same.

A new study has found that wild bees visit different flowers on purpose to get a balanced mix of protein, fats and carbohydrates.

Scientists recorded which flowers different species of wild bumblebees visited, then worked out what nutrients they were getting from the pollen.

The findings could help people design gardens which particularly meet bees' nutritional needs.

Scientists watched eight species of wild bumblebees over eight years in the Colorado Rocky Mountains, in the US.

After recording which flowers the bees visited, they then calculated the nutrients which were contained in the pollen.

The team of ecologists, led by Northwestern University and the Chicago Botanic Garden, found that instead of flitting from flower to flower randomly, the bees were making a decision on where to get their pollen based on the nutrient content of the flower.

The team collected pollen samples from around 35 different plant species and took them back to a lab to study.

There they were able to see how much carbohydrates, fat and protein was contained in each sample.

"All pollen contains protein, fats and carbs," lead author Justin Bain said. "But each type of pollen has a different mixture of these macronutrients. Some are very high protein like a steak. Others are more like a salad. So, the nutritional profiles are very, very different."

In some flowers, protein only made up 17% of the pollen, less than a quarter of the nutrients.

In other flowers, however, protein comprised as much as 86% of the total pollen which is very protein-rich.

What nutrients is this bee enjoying?

Researchers then compared each bee species' diet with their physical traits (like tongue length) and with what flowers were around during different seasons.

They found that there were some clear patterns.

Spring flowers, for example, have more protein-rich pollen, while late-summer flowers are richer in fats and carbohydrates.

This matches with the Queen bees which emerge in the Spring and collect protein-rich pollen.

The researchers also noticed the eight bumble bee species naturally divided into two groups.

Long-tongued species collected pollen with higher protein and lower fat and sugar.

Shorter-tongued species collected pollen with lower protein and higher sugar and fat.

The authors of the study say the findings highlight the need for conservation that focuses on nutritional diversity.

A mix of plants with different nutrition could help support the specific dietary needs of different wild bumblebee species.