The bee is not at all good for biodiversity

If bees die, humans will follow within two years, Albert Einstein once said. Although it is doubtful that the statement can be attributed to the famous scholar, it contains a grain of truth. Many crops, and indeed many plants in nature, depend on pollinators for their reproduction, insects that transfer pollen from flowers to stigmas.

It’s the work of the bee, many people think. Species of cultivated bee present almost exclusively in the hives of beekeepers. But that’s only half the story. Wild bees and bumblebees, butterflies and hoverflies play at least as important a role in plant pollination. Crops on the ground or in orchards cannot do without these wild pollinators.

In addition, the bee may have a reputation, it is actually only a moderate pollinator, wrote Wednesday American ecologists in the specialized journal. Proceedings of the Royal Society. Honey bees, unlike wild bees, are much more likely to stick to the flowers of a plant. As a result, the plant pollinates itself, which produces poorer fruit and seeds, the Americans found.

Become a healthy plant

The conservationists had already noticed typical bee foraging behavior in the rich wilderness around their university in San Diego. Moreover, previous research had shown that these bees played a predominant role in pollination in this nature reserve. The researchers therefore feared that the native plants would die by self-pollination.

Over several weeks, they peated three plant species to see which pollinator visited the flowers and how often each bee or bumblebee visited the same plant. They then studied the quality of the seed: how well it matured and how often it became a healthy plant.

Seeds from flowers fertilized by wild pollinators were two to five times better than the work of honey bees. This must be due to self-fertilization, they conclude. If they manually fertilized an individual plant with its own pollen, the result was two to ten times worse than cross-pollination.

Armed against monotony

We already suspected that the bee was not such a good pollinator, says David Kleijn, professor of plant ecology and nature conservation at Wageningen University. “But previous studies seemed to indicate that wild bees transferred more pollen. This research clearly shows that this is due to self-pollination.

What is less clear is what this result means for nature. Americans fear that the vegetation around San Diego is suffering from bee dominance. Especially because this bee does not exist naturally and therefore plants have not developed a defense against its behavior. But in Europe? The ancestor of the honey bee came from Africa, but it’s possible that similar types once buzzed here. Perhaps the plants here are better armed against its monotony.

Rather, the question is whether cultivated honey bees are replacing their wild counterparts. There are studies that indicate this, says Kleijn. “The further you go from the hives, the more wild bees you find. But the magnitude of this effect is difficult to study. Each area you study has a different number of flowers, honey bees, and wild pollinators. »

This does not change the fact that wild pollinators play a major role, explains Theo Zeegers of Eis Kenniscentrum Insecten. “Even if the beekeeper is involved, nature still does half the work on a rapeseed field. The ultimate question is therefore: is the bee necessary? And then I say: maybe for honey, but not for pollination. Although beekeepers disagree with this.

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