POLLINATORS POLLINATION AND FOOD PRODUCTION

THE ASSESSMENT REPORT ON POLLINATORS, POLLINATION AND FOOD PRODUCTION
suggest that the effects of artificial night lighting may cause
not only declines in moth populations – due to their negative
influence on reproduction and development – but might, as
a result, also cause potential changes in the composition of
moth assemblages and possibly in the ecosystem functions
they provide (MacGregor et al., 2015). Further studies are
needed to evaluate the extent of light pollution effects on
nocturnal pollinators.
2.3.5 Conclusions
It is clear that pollinators may be exposed to a wide range of
pesticides in both agricultural and urban environments. The
risk posed by pesticides is driven by a combination of the
toxicity (hazard) and the level of exposure; the latter being
highly variable and affected by factors including crop type,
the timing, chemical type, rate and method of pesticide
applications, as well as the ecological traits of managed and
wild pollinators. Insecticides are toxic to insect pollinators
and their exposure, and thus the risk posed, is increased
if, for example, labels do not provide use information to
minimise pollinator exposure or the label is not complied
with by the pesticide applicator. In addition, there is good
evidence from laboratory and in-hive dosing studies that
insecticides have the potential (depending on exposure
level) to cause a wide range of sublethal effects on individual
pollinator behaviour and physiology, and on colony function
in social bees, that could affect the pollination they provide.
However, significant gaps in our knowledge remain as most
sublethal testing has been limited in the range of pesticides,
exposure levels and species, making extrapolation to
managed and wild pollinator populations challenging. For
example, there is considerable uncertainty about how the
level, time course and combination of sublethal effects
recorded on individual insects in the laboratory might affect
the populations of wild pollinators over the long term. The
interaction between pesticides and other key pressures on
pollinators in realistic combinations and scales of stressors
(land-use intensification and fragmentation, climate change,
alien species, pests and pathogens) is little understood.
The GMOs (Genetically Modified Organisms) most used
in agriculture carry traits of IR (Insect Resistance), HT
(Herbicide Tolerance) or both. Though pollinators are
considered non-target organisms of GMOs, they can be
subject to direct and indirect effects. Direct effects of insect
pollinators’ exposure to IR-crops show that Bt-toxins are
non-lethal to Hymenoptera and Coleoptera, and can be
lethal to Lepidoptera pollinatoros. Sub-lethal effects on the
behavior and learning in honey bees have been reported in
one study. IR-crops result in a global reduction of insecticide
use, which in turn impact positively the diversity of insects.
Because of the use of herbicides, HT-fields harbor reduced
number of the weeds attractive to pollinators, what can lead
to a reduction of pollinators in GM-fields. Introgression of
transgenes in wild relatives (e.g. canola, cotton and maize)
and non-GM crops has been shown, but there is a lack
of evidence on the effect of these events on pollinators,
pointing to the need for more studies on this topic.
Pollutants pose a potential threat to pollinators. There
are numerous papers using honey bees and their hive
products as good indicators of environmental pollution
levels, indicating that honey bees can be directly exposed to
pollutants. Yet, detailed studies are still lacking concerning
the effects of various forms of pollution on bee biology.
Invertebrate models suggest that susceptibility of various
species of insects to industrial pollutants, like heavy metals,
can vary greatly due to various strategies used to cope with
such contamination. Some pollutants can bioaccumulate,
especially through plants and their products, like nectar
or pollen, and affect the level of exposure depending on
the pollinator species’ ecology. Large, between-species
differences in susceptibility and various plant-pollinator
dependences make it difficult to foresee the effect of a given
pollutant to the environment without direct field studies.
2.4 POLLINATOR DISEASES
AND POLLINATOR
MANAGEMENT
2.4.1 Pollinator diseases
Bee diseases by definition have some negative impacts at
the individual bee, colony or population level. As such, they
can be pointed to as potential drivers of pollinator decline
(Potts et al., 2010; Cameron et al., 2011a; Cornman et
al., 2012). Parasites and pathogens can be widespread
in nature but may only become problematic when bees
are domesticated and crowded (Morse and Nowogordzki,
1990; Ahn et al., 2012). Additionally, stressors such as
pesticides or poor nutrition can interact to cause disease
levels to increase (Vanbergen and the Insect Pollinators
Initiative, 2013). Disease spread can be a consequence of
bee management (detailed in section 2.4.2) and has been
most studied in honey bees, somewhat in bumble bees
and much less in other bees. Bee diseases can spillover
or move from one bee species to another (e.g. Deformed
Wing Virus (DWV) between honey bees and bumble bees)
and even within a genus the movement of managed bees
to new areas can spread disease to indigenous species
(e.g. Apis and Varroa, Morse et al., 1990; and Bombus and
Nosema, Colla et al., 2006). In addition to parasites and
pathogens in bees, bats, birds and other pollinators can
suffer from disease and thus impact pollination (Buchmann
and Nabhan, 1997). Diseases can directly impact pollinator
health but can also interact with other factors, such as poor
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2. DRIVERS OF CHANGE OF POLLINATORS,
POLLINATION NETWORKS AND POLLINATION