POLLINATORS POLLINATION AND FOOD PRODUCTION

THE ASSESSMENT REPORT ON POLLINATORS, POLLINATION AND FOOD PRODUCTION
108
2. DRIVERS OF CHANGE OF POLLINATORS,
POLLINATION NETWORKS AND POLLINATION
2.7.3 Case study 3: Bee nutrition
and stress from disease and
pesticides
Pollinators such as bees need an optimum balance of
nutrients across the individual and colony life-cycle to
support their growth and reproduction (Paoli et al., 2014).
Global environmental changes (land-use, climate, invasion
and pollution) have and continue to result in declines in the
diversity and abundance of flowering plants that provide
pollinators with pollen and nectar foods (Biesmeijer et al.,
2006; Carvalheiro et al., 2013; Carvell et al., 2006; Goulson
et al., 2008; Stevens et al., 2006) and with alterations
in their composition and quality (Barber and Gorden,
2014; Hladun et al., 2013; Lopezaraiza-Mikel et al., 2007;
Stout and Morales, 2009). These changes to pollinator
nutritional resources in contemporary landscapes may lead
to malnutrition of pollinator individuals and colony stress,
which in turn may increase their vulnerability to multiple
stressors such as pesticides and pathogens (Archer et
al., 2014; Goulson et al., 2015; Vanbergen and the Insect
Pollinators Initiative, 2013). Malnutrition in bees is known to
affect bee immune function and potentially the function of
enzymes used to break-down toxins in diet, so there is thus
a risk that this may exacerbate the individual and combined
impact of pesticides and pathogens on bees (Goulson et al.,
2015; Vanbergen and the Insect Pollinators Initiative, 2013).
Immune system activation has a metabolic cost to the
individual, and together with exposure to chemicals (section
2.3) and disease (section 2.4), can impair behaviours
important in locating floral resources, thereby intensifying
the underlying nutritional stress (Goulson et al., 2015;
Vanbergen and the Insect Pollinators Initiative, 2013).
2.7.4 Conclusion
Multiple pressures individually impact the health, diversity
and abundance of many pollinators across levels of
biological organisation spanning genetic to regional scales
(Cariveau and Winfree, 2015; González-Varo et al., 2013;
Goulson et al., 2015; Potts et al., 2010; Vanbergen and the
Insect Pollinators Initiative, 2013).
To date, evidence for a combined impact of different
pressures on pollinators and pollination is drawn from
relatively few laboratory experiments or correlative field
studies that only reflect a small subset of possible scenarios.
Doubtless, the precise interactions among different
pressures may vary with location, the balance of pressures
involved, and among pollinator species according to their
different genetics, physiology and ecology (Cariveau and
Winfree, 2015; Vanbergen, 2014). Nonetheless it is likely
that changes in pollinator biodiversity and pollination are
being driven by both the individual and combined effects of
multiple anthropogenic factors.
The potential consequences for future food security, human
health and natural ecosystem function mean it is crucial
that new experiments in field settings (e.g., Hoover et al.,
2012) are launched to disentangle the relative effects of
different drivers on pollinators and pollination (Cariveau and
Winfree, 2015; González-Varo et al., 2013; Potts et al.,
2010; Vanbergen and the Insect Pollinators Initiative, 2013).
Aside from this important challenge to advance knowledge
of the multifactorial pressure on pollinators and pollination,
there is an urgent need for decision makers to consider how
policy decisions are framed with regard to pollinators and
pollination. This may require joint framing across policy and
other sectors (e.g., science, business, NGOs) to capture
the individual and combined effects of different drivers.
The result may lead to more inclusive policy development,
taking into account the needs of various stakeholders and
advances in science.
2.8 INDIRECT EFFECTS
IN THE CONTEXT OF
GLOBALIZATION
Indirect drivers are producing environmental pressures
(direct drivers) that alter pollinator biodiversity and
pollination. Major indirect drivers relevant to this assessment
include the growth in global human population size,
economic wealth, globalised trade and commerce, the
less stringent environmental regulations in those nations
where other markets exist, and technological and other
developments, e.g., increases in transport efficiency, or new
impacts on land use and food production through climate
change adaptation and mitigation (Watson, 2014). These
have transformed the climate, land cover and management
intensity, ecosystem nutrient balance, and biogeographical
distribution of species, and continue to produce
consequences for pollinators and pollianation worldwide
(2.2-2.7).
Humans now exploit approximately 53% of the Earth’s
terrestrial surface. For example, croplands are expanding
at continental and global scales, with predictions of a net
forest loss associated with a 10% increase in the area of
agricultural land by 2030, mainly in the developing world.
Urban areas are also projected to expand with 66% (vs.
54% today) of the increasing global human population
expected to be living in urban areas by 2050 (Ellis et al.,
2010; Ellis, 2011; Foley et al., 2005; Foley et al., 2011;
Steffen et al., 2011). Increased incomes in emerging
economies have driven increased land devoted to pollinatordependent
crops (Monfreda et al., 2008).
International trade is an underlying driver of land-use
change, species invasions and biodiversity loss (Hill et al.,