Too few flowering plants in agricultural landscapes often is among the reasons for the decline of pollinating insects.
Researchers at the University of Göttingen have now investigated how a mixture of crops of faba beans (broad beans) and wheat affects the number of pollinating insects. They found that areas of mixed crops compared with areas of single crops are visited equally often by foraging bees. Their results were published in the journal Agriculture, Ecosystems & Environment.
The researchers observed and counted foraging honeybees and wild bees in mixtures of wheat and faba bean and in pure cultures that only contained faba beans.
“We had expected that the mixed crops with fewer flowers would be visited less frequently by bees for foraging than single crops,” says PhD student Felix Kirsch from the Functional Agrobiodiversity research group, University of Göttingen.
“To our surprise, this was not the case.”
This could be due to several reasons.
“Our mixed cultures were less dense than pure cultures, which possibly increased the visibility of the flowers. This might have attracted the similarly large number of bees to the mixed cultures,” suggests Dr Annika Haß, postdoctoral researcher in the Functional Agrobiodiversity research group.
Professor Wolfgang Link, head of the group for Breeding Research Faba Bean, says reduced competition between the faba bean plants in mixed cultures could mean that they can invest more resources in the production of nectar and pollen to increase their attractiveness to bees
And Professor Catrin Westphal, Head of Functional Agrobiodiversity,says mixed cultivation of wheat and faba bean has other advantages for crop production.
For instance, yields per bean plant were higher in mixed crops than in pure cultures.
Dr Haß concludes that cereal crops can be ecologically enhanced by adding legumes such as beans or lentils. This can make a valuable contribution to increasing the abundance of flowers on the arable land and thus counteract pollinator decline.
- Felix Kirsch, Annika L. Hass, Wolfgang Link, Catrin Westphal. Intercrops as foraging habitats for bees: Bees do not prefer sole legume crops over legume-cereal mixtures. Agriculture, Ecosystems & Environment, 2023; 343: 108268