influence of habitat transformation,
injudicious pesticide use and various diseases and parasites introduced with global trade. In addition forage available to managed
and wild bees are continuously on
the decline because landscapes are
being transformed.
The Science study found that increasing the numbers of wild insects that pollinate flowering crops
on smallholdings has the most pronounced effect on production volumes when the land is smaller than
two hectares. In such cases yield
can be increased by up to 24%.
“The effectiveness of ecological intensification through pollination
services is greater for smallholdings,
rather than larger farms,” notes
study leader Prof Lucas Garibaldi of
the National University of Rio Negro
in Argentina.
The authors further suggest that
large-scale crops may also 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.
This study defines a farm as large if
it is planted with more than two
hectares of crops (was on average
14 ha). Furthermore, such farms
often occur adjacent or near to other similar-sized farms. This creates
vast areas of transformed landscapes with only a few small patches of natural growth in between.
These can only support a handful of
different types of wild pollinators,
which are 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 Dr Veldtman.
Increasing yield on typically large
commercial farms is therefore not
simply a matter of attracting a
greater variety and more wild pollinators. Yield can only increase if
commercial farmers ensure ade-
quate visitation by enough pollinators to their entire operation, across
all the hectares of flowers that need
pollination. In practice this means
that they need to set out enough
managed bee hives on their land.
Acknowledgement:
This article is based on Garibaldi,
L.A. et al (2016). Mutually beneficial pollinator diversity and crop
yield outcomes in small and large
farms. Science 351(6271): 388-391.
Additional information
For more information on the Global
Pollination Project: www.fao.org/
pollination/en/
OR
South African National Biodiversity
Institute honeybee forage project
Contact:
Dr Ruan Veldtman
Researcher of the South African
National Biodiversity Institute and
Stellenbosch University
[email protected]
021 808 9441