POLLINATORS POLLINATION AND FOOD PRODUCTION

THE ASSESSMENT REPORT ON POLLINATORS, POLLINATION AND FOOD PRODUCTION
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3. THE STATUS AND TRENDS IN POLLINATORS
AND POLLINATION
(increases, decreases, no change) found among countries
within continents (well established). On the other hand,
the status of shifts in abundance and distribution of wild
honey bees (Apis mellifera and other Apis species) is largely
unknown, with the exception of some records on the spread
of the Africanized honey bee in the Americas (established
but incomplete) (3.3.2).
Trade in and movement of the managed western
honey bee, Apis mellifera, has led not only to it being
a global presence (Antarctica excluded), but also
to spillover of pathogens and parasites. Particularly,
the shift of the varroa mite (Varroa destructor), originally
a parasite of the Asian honey bee Apis cerana, to the
western honey bee has led to severe loss of beehives and
makes beekeeping more difficult and costly in many regions
(established but incomplete). The Varroa mite is associated
with viruses, such as the deformed wing virus, which is now
spreading to bumble bees and wild bees with yet unknown
consequences (unresolved). The impact of the invasion
of honey bees, such as the Africanized honey bee in the
Americas, on native bee communities and animal-pollinated
plants remains largely unclear (unresolved) (3.4.2, 3.4.3).
Commercial management, mass breeding, transport
and trade in pollinators outside their original ranges
have resulted in new invasions, transmission of
pathogens and parasites and regional extinctions of
native pollinator species (well established).Recently
developed commercial rearing of bumble bee species for
greenhouse- and field-crop pollination, and their introduction
in other continents outside of their original ranges, have
resulted in numerous cases of biological invasion, pathogen
transmission to native species and the decline of congeneric
(sub-)species (established but incomplete). A welldocumented
case is the severe decline in and extirpation
from many areas of its original range of the giant bumble
bee, Bombus dahlbomii, since the introduction and spread
of the European B. terrestris in southern South America (well
established) (3.2.3, 3.3.3, 3.4.2, 3.4.3).
More food is produced every year and global
agriculture’s reliance on pollinator-dependent crops
has increased in volume by more than 300 per cent
over the last five decades (well established). Because
the degree of yield dependency on pollinators varies greatly
among crops, pollinators are responsible, in a direct way
(i.e., the production of seeds and fruits we consume),
for a relatively minor fraction (5-8%) of total agricultural
production volume (well established). However, pollinators
are also responsible for many indirect contributions, such
as the production of many crop seeds for sowing but
not consumption (well established). The small fraction
of total agricultural production that depends directly on
pollinators has increased four-fold during the last five
decades, whereas the fraction of food production that does
not depend on pollinators has only increased two-fold.
Therefore, global agricultural is now twice as pollinatordependent
compared to five decades ago, a trend that has
been accelerating since the early ‘90s (well established).
Agricultural production, in terms of volume, of some
Mediterranean and Middle East countries is particularly
dependent on pollinators because of the cultivation of a
large variety of temperate and subtropical fruit and seed
crops. Rapid expansion of many of these crops in other
countries (e.g., China) and cultivation of some geneticallyengineered
and moderately pollinator-dependent crops, like
soybean (e.g., Argentina, Paraguay, Uruguay, and Bolivia)
and canola (oilseed rape) (Canada) are responsible for
the large increase in the pollinator dependency of global
agriculture (established but incomplete) (3.7.2, 3.7.3).
Decreased crop yield relates to local declines
in pollinator diversity (well established), but this
trend does not scale up globally (established but
incomplete). At the local scale, yield of many pollinatordependent
crop species is positively related to wild
pollinator diversity. As a consequence, reductions in crop
yield have been found in agricultural fields with impoverished
bee faunas despite high honey bee abundance (well
established). While pollination efficiency varies considerably
between species and crops, wild bees as a group have
been found, on average, to increase crop yield twice as
much as honey bees on a per-visit basis (well established).
A Global analyses of FAO data did not show slowing in yield
growth of pollinator-dependent crops relative to pollinatorindependent
crops over the last five decades (1961-2007)
(established but incomplete), although the trend in declines
of some native bees may change this situation (3.8.2, 3.8.3).
Globally, yield growth and stability are, between
1961-2008, negatively associated with the increasing
dependency of crops on biotic pollination (well
established). Despite no sign of deceleration in average
yield growth among pollinator-dependent crops over time,
FAO data revealed that yield growth, and yield stability are all
negatively related to increasing crop pollinator-dependency
(well established) (3.8.3).
Cultivation of pollinator-dependent crops largely
accounts for the 30% expansion of the global
cultivated area occurring during the last fifty years
(well established). FAO data revealed that crops that
largely depend on pollinators have experienced the fastest
global expansion in cultivated area (well established).
However, these crops exhibited the slowest average
growth in yield and highest inter-annual yield variability (well
established) (3.7.3, 3.8.3).