Without a crucial ingredient, more bees won’t help the world’s farms

Pollinator biodiversity has wide-ranging benefits for farms.

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Scientists have warned for years about the importance of protecting bees and other pollinators, which play a critical role in helping our food grow. But pollinator populations are declining worldwide, raising grave questions about what the future of food will look like without the insects we depend on to pollinate our crops. And unfortunately it’s not just about getting more insects out into the world.

While there’s strength in numbers, big populations alone may not yield the best outcomes, says a study published Wednesday in the journal Science Advances: Species diversity has its own important role to play in farm productivity. And there are some simple things that can be done to encourage this diversity.

The team behind this research looked at dozens of studies from locations around the world to uncover trends in how, exactly, pollinators and other “service-providing organisms” fit into agricultural ecosystems.

Those species “work for humans at no cost,” lead author Matteo Dainese, Ph.D., senior researcher at Eurac Research’s Institute for Alpine Environment in Italy, tells Inverse via email.

“In many ways, nature is an outstanding service provider for agriculture,” Dainese says. “For example, wild bees pollinate fruit trees and other crops, while predatory ladybugs eat pests that would otherwise damage or even destroy crops.”

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Species richness, Dainese’s team found, benefits those human-feeding ecosystems “in addition to and independent of” high population numbers. That could have major implications for shaping the future of agriculture across the world.

“We show that agricultural fields with a greater diversity of these ‘beneficial’ insects are better protected from harmful insects, promote pollination, and produce higher yields,” Dainese says.

Dramatically altering land for agriculture, called landscape simplification, can kill off pollinators’ food and resources, alter their species pool, and even change their interactions.

As a result, Dainese points out, monocultures — vast fields of the same crop — deplete diversity and abundance of “useful insects,” making crops less productive.

The researchers measured the damages of landscape simplification on pollinators and found that biodiversity loss may account for 50 percent of those negative effects.

Loss of species richness accounts for half of the negative outcomes associated with intense land clearing.  

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Real-world ecosystems tend to have a handful of highly abundant species that dominate, as well as many rare ones. Understanding the dynamics of both can help farms become more productive, and therefore sustainable, Dainese’s team says.

On farms, “richness and total and relative abundance are not mutually exclusive but concurrently contribute to support pollination and pest control services,” Dainese says.

The findings add to the conversation around land-use change and management. In a recent report, the Intergovernmental Panel on Climate Change warned that humans need to overhaul our land management practices, particularly related to agriculture and livestock, in order to avoid the worst outcomes of climate change.

The IPCC recommends protecting agricultural systems against biodiversity loss and land degradation, saying that “locally appropriate policies and governance systems” will be key to preventing these harms.

Dainese agrees: “Diversification could be as simple as adding wildflower strips, trees or hedgerows along the edges of fields, giving these beneficial species places to live,” he says.

“Humans must ensure the greatest possible biodiversity to develop a more sustainable food production globally.”

Abstract: Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield–related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.
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