By planting flower strips, using pesticides more carefully and restoring natural areas around their farms, smallholder farmers can harness nature’s free pollination service. This is according to an international study on pollinators, which asserts that attracting more wild honeybees to such lands could result in an increase in yield of up to 24%.
The project stems from the Global Action on Pollination Services for Sustainable Agriculture Project (GPP), funded by the Global Environmental Facility and co-ordinated by the UN’s Food and Agricultural Organisation. Amongst the pollination experts and ecologists who co-authored the study was ecological entomologist Dr Ruan Veldtman of the South African National Biodiversity Institute (SANBI) and Stellenbosch University.
The study, which commenced in 2010, collected data from 344 croplands and orchards in smallholdings and large farms in Argentina, Brazil, Colombia, Ghana, India, Indonesia, Kenya, Nepal, Pakistan, South Africa and Zimbabwe.
It noted the number and variety of pollinators in each land and the yield of each crop over a five-year period. It also recorded the resources needed – such as plants that produce pollen and serve as forage – to ensure that local populations of wild bees remained healthy enough to provide free pollination services.
The South African data was collected by SANBI scientists in a sunflower seed-producing area in Limpopo. The GPP fully or partially funded the postgraduate research of two masters students and two doctoral students at Stellenbosch University’s faculty of agricultural sciences on the pollination of apples and hybrid seed onions and forage to support managed honey bees.
“Pollinators are an all-important link in the cycle of food production,” says Dr Veldtman, who explains that most flowering plants, including many that are used for food, produce seeds only with the help of animal pollinators.
“We need to treasure our wild bee populations as well as the managed honey bees that our beekeepers set out in orchards and lands to ensure that pollination takes place.”
As a result of the influence of habitat transformation, injudicious pesticide use, and diseases and parasites introduced with global trade, pollinating insects are on the decrease. In addition, forage available to managed and wild bees is continually on the decline as landscapes are being transformed.
Smallholders benefit the most
According to study leader Prof Lucas Garibaldi of Argentina’s National University of Rio Negro, the effectiveness of ecological intensification through pollination services is greater in smallholdings than larger farms.
The study found that increasing the numbers of wild insects that pollinate flowering crops has the highest effect on production when the land is smaller than 2ha. In such cases, yield can be increased by up to 24%.
The study further suggests that large-scale crops may benefit less from wild pollinator density because these tend to be pollinated by flower visitors with longer foraging ranges. These are usually generalist species, such as honey bees.
The study defined a farm as large if it had more than 2ha of planted crops. (The average was 14ha.) Such farms often occur adjacent or near to other similar-sized farms, creating vast areas of transformed landscapes, with only a few small patches of natural growth in between. These can support only a handful of different types of wild pollinators – not enough to adequately pollinate adjacent crops.
“Using managed bees provided by beekeepers will therefore remain an important part of commercial farmers’ operations, despite the free services that wild pollinators could offer,” says Veldtman.
Increasing yield on typically large commercial farms is therefore not simply a matter of attracting more, and a greater variety of, wild pollinators. Yield can only increase if commercial farmers ensure adequate visitation by enough pollinators across all their lands or orchards. In practice, this means that they need to set out enough managed beehives on their land.
This article is based on the article, ‘Mutually beneficial pollinator diversity and crop yield outcomes in small and large farms’, which appeared in the 22 January 2016 issue of the journal Science.
For more information on the Global Pollination Project, visit www.fao.org/pollination/en.
Phone Dr Ruan Veldtman on 021 808 9441 or email him at [email protected].