Six flower species can quickly boost insect numbers

NEWS

POLICY & LEGAL

Heleen Kommers, Tuesday 18 August 2026

92 sec

Greater variety needed for the return of rare wild bees

Flower-rich dykes can make an important contribution to biodiversity. A wide variety of flowers is particularly beneficial to wild bees and other pollinators. Research by ecologist Constant Swinkels at Radboud University Nijmegen shows that six to seven flower species already make a major difference to insect numbers. However, even greater variety is needed for the most vulnerable wild bees.

Value of flower-rich dykes demonstrated (Image for illustration, generated with AI)

For his research, Swinkels spent hundreds of hours on various dykes around Nijmegen. He studied which flowers were present and which wild bees and bumblebees were attracted to them. He also analysed pollen grains on the insects' legs to see which flowers were popular and how different pollinator species divide the available food.

With six or seven flower species, more than half of the increase in insect numbers can already be achieved

More flowers quickly produce results

The research shows that even a relatively small increase in the number of flower species can have a major effect. At locations with six or seven different flower species, more than half of the total increase in insect numbers was already visible. Plants such as knapweed, red clover, dandelion and buttercup can make a significant difference.
Flower-rich locations had two to three times as many insects as sites with little plant diversity. Variation in flower shape and flowering period is particularly important, because it gives different insect species access to suitable food.

Vulnerable wild bees need a greater variety of plants

Rare species need greater diversity

For wild bees, the benefits do not stop with more flowers. At a certain point, the numbers of common species increase less rapidly, but this is precisely when more room emerges for rarer species. Swinkels found that threatened wild bees often have more specific habitat requirements. They are more selective about their food and need specific places to nest.
When a greater variety of flowers is available, pollinators can divide the available food more effectively. Bees are more likely to choose their preferred plants, reducing overlap in food use between species. This creates more opportunities for species on the Red List.

Dykes can form green corridors between natural areas

Dyke management as an opportunity for biodiversity

According to Swinkels, dykes can play an important role in restoring wild bee populations. They provide space for flowers, while their warm slopes are suitable for larval development. When several dykes are managed to encourage flower-rich vegetation, they can also serve as corridors between natural areas.
For municipalities and land managers, the research shows that targeted management of dyke grasslands can quickly have an effect. Greater vegetation diversity not only creates a more attractive landscape, but also provides more space for pollinators and vulnerable insect species.

This article was previously published on 17 August 2026 on the website of Stad + Groen.

Radboud Universiteit

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