The quiet work of pollinators

Stand at the edge of a flowering orchard on a warm morning and listen. The hum is the sound of a service that no farmer invoices and no market prices.

Laisha's manual on ecosystem services and pollinators starts from a simple idea: farms are ecosystems. They depend on services that nature provides, from the bees that carry pollen to the soil organisms that build fertility, and they in turn produce food while changing the services that neighbours downstream, and people in the future, will receive.

Ecosystem services, the benefits people obtain from ecosystems, have been gathered into frameworks over the past three decades. The Millennium Ecosystem Assessment of 2005 sorted them into four families: provisioning services such as food, fibre, fuel and fresh water; regulating services such as climate regulation, flood control, pollination and pest control; cultural services such as recreation, heritage and a sense of place; and supporting services such as soil formation and nutrient cycling, which make the others possible. It found that about 60 per cent of the services it examined, 15 of 24, were being degraded or used unsustainably. Today the intergovernmental science-policy platform on biodiversity, IPBES, speaks of “nature's contributions to people”.

Regulating services are the ones most easily forgotten, because they are often invisible until they are lost. When wetlands are drained, floods do more damage. When hedgerows are removed, wind erosion and pest outbreaks rise. When pollinators decline, fruit set falls. Many of these services work at the scale of the landscape rather than the field, so one farmer's hedgerow helps the neighbours' pollination and pest control as well as their own.

The numbers behind pollination

The numbers behind pollination are striking. A widely cited global study from 2007 found that 87 of the 115 leading food crops, about three-quarters, benefit to some degree from animal pollination. Yet those crops make up only about a third of global food production by volume, because the great staple cereals do not need animals to carry their pollen. The IPBES pollination assessment of 2016 estimated that 5 to 8 per cent of global crop production is directly attributable to animal pollinators, and that pollinator-dependent crops supply much of the vitamin A, vitamin C and folate in human diets. Fruits, vegetables, nuts, oilseeds such as mustard and sunflower, coffee and cocoa all depend on pollinators, some a little and some completely.

There are more than 20,000 species of bee, and the managed honey bee is only one of them. Wild bees and other insects often pollinate more effectively, and a diverse community of pollinators raises fruit set even where honey bees are plentiful. The same assessment found that wild pollinators have declined in occurrence and diversity in many regions: 16.5 per cent of vertebrate pollinators, such as some birds and bats, are threatened with global extinction, and where regional assessments exist, often more than 40 per cent of invertebrate pollinator species, particularly bees and butterflies, are threatened. The drivers include lost habitat, monocultures and pesticides, parasites such as the Varroa mite, invasive species and a changing climate.

Pollinator-friendly farming

The good news is that pollinator-friendly farming is practical. Wildflower strips, flowering hedgerows, field margins and cover crops such as clover and mustard provide food through the season. Bare ground for ground-nesting bees, and dead wood and hollow stems for cavity nesters, provide homes. Integrated pest management, no spraying during flowering or while bees forage, less toxic products and margins protected from drift all reduce the risk from pesticides. Where pollinators have collapsed, the cost becomes visible: apple growers in parts of the Himalaya and south-west China have had to rent honey bee colonies or pollinate flowers by hand. In Luxembourg, this issue's country, old meadow orchards of tall fruit trees are treasured for their wildlife.

One farmer's hedgerow helps the neighbours' pollination and pest control as well as their own.

Is pollination limiting the harvest?

How does a farmer know whether pollination is limiting the harvest? The manual describes a simple, powerful experiment. Bag some flowers so no visitor can reach them, leave others open, and pollinate a third group by hand as fully as possible. The gap between open and hand-pollinated flowers is the pollination deficit; the gap between open and bagged flowers is what pollinators already contribute. Studies across Asia, Africa and Latin America, on crops from mustard and sunflower to pigeonpea, coffee and apple, have found that wild bees add substantially to yield and quality.

The other unpaid workforce

Pollinators share the field with another unpaid workforce: ladybirds, lacewings, ground beetles, spiders, birds and bats that eat pests, and tiny wasps and flies that lay their eggs in them. Flower strips, beetle banks, hedgerows, intercropping and fewer broad-spectrum insecticides all help these allies. In East Africa, the push-pull system plants maize with a legume, Desmodium, that repels stemborer moths, and borders it with a trap grass that draws them away; Desmodium also suppresses the parasitic Striga weed and fixes nitrogen. Results vary from place to place, the manual warns, so design for the system, then measure.

Soil, and counting what nature supplies

Beneath the crop, soil forms slowly, commonly well under a millimetre a year, while erosion on bare, sloping land can remove several millimetres a year; where erosion is high, soil is effectively non-renewable on a human time scale. Cover crops, reduced tillage, agroforestry and buffer strips keep soil in place and water clean.

The world is also learning to count these services. Since 2021 an international statistical standard, SEEA Ecosystem Accounting, has recorded the extent and condition of ecosystems and the services they supply, which GDP alone ignores, and food companies are beginning to assess how much they depend on pollination, water and healthy soil.

Global figures should never be applied to a single farm without local data, the manual cautions. But the direction is clear: every flower strip, every hedgerow and every season without an unnecessary spray pays back into the account that farming draws on.