POLLINATORS POLLINATION AND FOOD PRODUCTION

THE ASSESSMENT REPORT ON POLLINATORS, POLLINATION AND FOOD PRODUCTION
60
2. DRIVERS OF CHANGE OF POLLINATORS,
POLLINATION NETWORKS AND POLLINATION
Of the separate incidents of honey bee mortality in Europe
where insecticides were detected (an incident may include
more than one coloniy or more than one apiary site), 27%
contained organophosphorus insecticides or carbamate
compounds, 14% contained organochlorine insecticide
(gamma-HCH (lindane), and dieldrin) and pyrethroid
insecticides were present in 7.8% of incidents; none were
associated with neonicotinoids (Thompson and Thorbahn,
2009). Between 1981 and 1991 around 65-70% of the 545
incidents in the UK were identified as due to farmers not
complying with label instructions and applying insecticides in
flowering beans, peas and oilseed rape, or crops containing
flowering weeds (Greig-Smith et al., 1994); of the remainder
3% were associated with aerial applications (no longer
permitted in the UK), 2% with use in feral bee control and
in the remainder of reported incidents the use often could
not be clearly identified from the information available.
These incidents have resulted in improved regulation and
enforcement in Europe (e.g. Directive 91/414 EEC) with
subsequent reduction in incidents as well as providing
information where uses according to the label require further
education of farmers (Thompson and Thorbahn, 2009). For
example, the reduction in the number of reported aphid
honeydew-related insecticide incidents in the Netherlands
from 119 in 2003 to 17 in 2006 was attributed to the
reduction in the aphid control threshold for insecticide use
in potatoes, which limited the availability of aphid honeydew
(a source of sugar) and thus attraction of honey bees to the
crop (Thompson and Thorbahn, 2009).
These experiences from countries with incident schemes
suggest that where there is no effective regulation or
enforcement of key mitigation (Heong et al., 2013), it is likely
that incidents of insecticide-associated honey bee mortality
FIGURE 2.3.4
Comparison of the risk index (HQ = application
rate/LD50) with the number of honey bee incidents
in which the pesticide was detected. Data are
from the UK, Germany and the Netherlands 1985-
2007. An HQ of 50 is used in risk assessments
for pesticides to identify those uses that require
further evaluation. Incidents may also contain
pesticides not related to bee mortality, e.g. 1)
fluvalinate used as a varroacide (to control the
Varroa mite) and 2) captan, a fungicide applied at
high rates (Thompson and Thorbahn 2009). The
circles highlight the groupings of incidents involving
different classes of insecticides. For reference
the HQ of the neonicotinoids imidacloprid,
thiamethoxam and clothiandin are >1000 but no
incidents were reported.
Number of honey bee incidents
700
600
500
400
300
200
100
are occurring; in the absence of honey bee impacts effects
on wild bees are unclear. Mitigation measures to protect
honey bees include only applying insecticides outside the
flowering period, and closing or removing beehives or
use of low-drift technology to reduce drift of spray onto
nearby flowering crops or hedgerows containing flowering
plants. To be effective, mitigation needs to take account of
local practices and also apply to other insect pollinators.
For example, beekeepers keeping native bees in Korea
have reported that impacts of pesticide spray cannot be
avoided because their hives cannot be moved (Park and
Youn, 2012).
These incident data have also been used to derive the
hazard quotient (application rate (g active ingredient/ha)/
LD 50
(µg active ingredient/bee)) threshold of 50 to identify
those uses of foliar applied pesticides with a risk of resulting
in acute honey bee mortality and requiring further evaluation
in the risk assessment, e.g., semi-field and field studies
(EPPO, 2010). A comparison of the hazard quotient (HQ)
with the number of incidents reported is shown in Figure
2.3.4. Although the HQ for pyrethroid insecticides is far
greater than 50 there is good evidence that, when applied
according to the label, particularly at lower application
rates, and not mixed with ergosterol biosynthesis-inhibiting
(EBI) fungicides (see pesticide mixtures section) honey
bee incidents are rarely observed due to the repellent
properties of some of this class of insecticide (Thompson
and Thorbahn, 2009). These national monitoring schemes
have shown a decrease in the overall number of incidents
reported over the last 20 years following reactive changes
to product registrations and stewardship, e.g. limiting
applications to non bee-attractive crops. However, high
profile incidents are still reported such as the off-label use of
HQ=50
Organophosphorus,
carbamate
insecticides
and gamma HCH
Pyrethroid
insecticides
0
1 10 100 1000 10000 100000
Risk index (HQ = application rate/LD50)