POLLINATORS POLLINATION AND FOOD PRODUCTION

THE ASSESSMENT REPORT ON POLLINATORS, POLLINATION AND FOOD PRODUCTION
CHAPTER 3
THE STATUS AND TRENDS
IN POLLINATORS AND POLLINATION
EXECUTIVE SUMMARY
Many wild bees and butterflies have been declining
in abundance, occurrence and diversity at local and
regional scales, as it has been recorded in North
West Europe and North America (established but
incomplete). Loss of pollinators has negative impacts
on the reproduction of wild plants (established but
incomplete). In agricultural systems, the local abundance
and diversity of wild bees have been found to decline
strongly with distance from field margins and remnants
of natural and semi natural habitat at scales of a few
hundred metres (well established) (3.2.2, 3.2.3). At larger
spatial scales, declines in bee diversity and shrinkage of
geographical ranges, e.g. of bumble bees, have been
recorded in highly industrialized regions of the world,
particularly Europe and North America, over the last century
(well established). Beyond records of species-specific
population declines, e.g. Franklin’s bumble bee (Bombus
franklini) in Western USA and the giant bumble bee (Bombus
dahlbomii) in Southern South America, trends are mainly
unknown for other regions and continents because of a
lack of baseline datasets and monitoring schemes (3.2.3).
Declines have been also recorded in other insect pollinator
groups, such as butterflies and moths, and among some
vertebrate pollinators, particularly hummingbirds and
bats (established but incomplete) (3.2.1, 3.2.2). Local
declines in pollinator abundance and diversity have been
linked to decreasing trends in wild plant pollination and
seed production in habitat fragments (well established),
and to declines in the diversity of pollinator-dependent
wild plant species at regional scales (established but
incomplete) (3.6.3).
The International Union for Conservation of
Nature (IUCN) Red List assessments indicate
that
16.5 per cent of vertebrate pollinators are threatened
with global extinction (increasing to 30 per cent
for island species). There are no global Red List
assessments specifically for insect pollinators.
However, regional and national assessments indicate
high levels of threat for some bees and butterflies. In
Europe, 9% of bees and butterfly species are threatened
and populations are declining for 37% of bees and 31% of
butterflies (excluding data deficient species, which includes
57% of bees). Where national Red List assessments are
available, they show that often more than 40 per cent of bee
species may be threatened (3.2.1, 3.2.3).
Large and well-connected plant-pollinator networks,
i.e., those with many links between the plants and
pollinators, are needed to guarantee satisfactory
levels of pollination for wild plants and crops, as
well as sufficient availability of food for pollinators
(established but incomplete). Wild and domestic
pollinators involved in crop pollination also require floral
resources provided by wild plants (well established).
Therefore, large, and well-connected plant-pollinator
networks are associated with viable populations and diverse
communities of pollinators (established but incomplete).
Habitat disturbance tends to lead to loss of interaction links
and species from plant-pollinator networks (established but
incomplete) (3.5.2, 3.5.3).
There is a loss of indigenous and local knowledge
and sustainable bee management practices within
local communities (established but incomplete). Shifts
in social systems, cultural values, and accelerated loss of
natural habitats have been associated with a decrease in
the transfer of knowledge within and between generations.
This has led to a decline in stingless bee husbandry in the
Americas and Africa and changes in habitat management
for wild honey bee species in Asia by local and indigenous
communities (established but incomplete). Whether this has
led to loss of pollination of crops and wild flowering plants
remains unknown (3.9.1).
The number of managed western honey bee hives
is increasing at the global scale, although seasonal
colony loss is high in some European countries and
in North America (well established). FAO data show
that the number of western honey bee hives has increased
globally by about 50% over the last five decades, despite
a temporary drop during the 1990s after the dissolution of
the Soviet Union and Eastern-European Soviet Bloc (well
established). It is unknown whether this decline is an artefact
of how data were collected and reported, or the result of
a true decrease in honey bee hives that resulted from the
political and economic disruption caused by the Soviet
collapse (unresolved). FAO data also show that national
trends vary widely among countries, with contrasting trends
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3. THE STATUS AND TRENDS IN POLLINATORS
AND POLLINATION