Closing the food cycle: Diverse diets essential for honeybee nutrition, research reveals

06 Oct 2023 --- Honeybees play a crucial role in human food chains due to the delicious honey they produce and their pollination of essential crop plants.Therefore, the decisions bees make while collecting nectar and pollen are significant for their well-being as well as the health of humans.

A fresh perspective on bees’ plant-pollination preferences, enabled by DNA metabarcoding, was recently unveiled in the journal Scientific Reports.

While these insects have been traditionally viewed as generalists in selecting flowering plants and gathering nutrients from a broad spectrum of flora, the discoveries in this paper indicate that they are likely to be more selective eaters than previously believed.

“The study shows how to determine more precisely which crop and wild plants the honeybees use in a region at a time point, Helena Wirta, co-author of the study and a researcher from the faculty of forestry and agriculture at the University of Helsinki, Finland, tells Nutrition Insight. “This is done by identifying the floral sources honeybees use by DNA metabarcoding for both nectar and pollen.“

The eating habits of bees
Bee hives are found in various natural environments worldwide and the types of plants available to bees for pollination can directly influence their health. In particular, the insects thrive when they consume a balanced diet. Honeybees have been shown to enjoy a varied diet and the monocultures typical of modern agriculture are insufficient.

However, with modern agriculture rapidly taking over natural surroundings, monocultures are becoming the norm, and these cannot meet the nutritional needs of honeybees.

The researchers focused on 43 honeybee colonies and the species of plants flowering during this period, all found in Southern Finland in 2021.

“In the specific region, based on the relative abundance of DNA reads, honeybees used for both nectar and pollen by far the most rapeseed, brassica (the cabbage family), across the summer, and other cultivated plants used relatively most abundantly were pisum (peas) and trifolium (clovers),” says Wirta.

“Yet, other more relatively abundant ones were wild plants, such as filipendula, salix (willow), myosotis (forget-me-nots) and rubus (brambles).

The scientific paper explains that plants differ in their protein content, the composition of amino and fatty acids of pollen and the sugars in their nectar. Honeybees choose plants based on whether or not their pollen and nectar meet the insects’ nutritional needs.

Improving our understanding of the nutritional needs of bees is vital to ensure the appropriate flower selection is made available to them during the summer months.

“Overall, the study shows that honeybees dominantly use one cultivated plant and several wild plants, apparently to complement their diet. They contribute to the yield of cultivated plants by pollinating them. However, they need wild plants as well,” continues Wirta.

Pesticides stressing bees out
“Based on our results, honeybees are more selective than assumed, using only a fraction of available plants. Thus, to fulfill its nutritional needs, it is likely to need a wide selection of plants from which to select suitable ones,” Wirta further points out. Honeybees are vital pollinators of both crops and wild plants.

In addition, the study further reveals that honeybees’ appetite for varied sources of nutrients is especially noticeable when they experience stress. Meanwhile, one of the most significant stress factors for bees is exposure to pesticides that go hand in hand with modern agriculture.

Earlier this year, research in the EU revealed that the chemical glyphosate, commonly used in weedkillers, is particularly harmful to honeybees, as it damages their digestive systems, making them vulnerable to infections and other complications.

With mounting evidence about the harmful effects of pesticides on honeybees, such as the results of this recent study on bees’ feeding habits, the EU is set to vote on whether to reauthorize glyphosate.

These latest findings are particularly pertinent to the topical issue of food security, with bees being an important pollinator to crops and wild plants.

“To ensure food security, including a variety of plants with high nutritional value, we should consider these new findings,” Wirta says.

By Milana Nikolova

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