Neonicotinoid Pesticides and Bees - The Food and Environment ...

colonies and therefore residues may be diluted. For pesticides (not acaracides) the residues
detected in the monitoring studies are lower than those reported in field studies.
Water is collected by honeybees to dilute thickened honey, to produce brood food from stored
pollen, to maintain humidity within the hive and to maintain temperature within the brood area.
Water is not stored in combs by temperate bee colonies. The amount of water required depends
on the outside air temperature and humidity, the strength of the colony and the amount of brood
present. The production of water by evaporation of nectar to form honey may address at least
some of this need. Water consumption by honeybee colonies has been assessed using confined of
colonies provided with a source of water within the hive. To date there have been no published
studies that demonstrate significant exposure of bees to guttating crops as a source of water in the
field. Guttation fluid is unlikely to be identified by honeybees as a source of sugar due to the low
levels present. Bees are less subject to dessication than most terrestrial insects due to their nectar
diet and high metabolic water production
Beeswax is produced by worker bees within the colony to house stores of nectar and pollen and for
brood production. Production begins when the worker is slightly less than one week old, peaking at
around two weeks and then reducing. It takes between 24 and 48 hours for any particular
honeybee worker to produce a moderate-sized wax scale. If unchanged by a beekeeper wax within
the colony may accumulate lipophilic residues over time both from contaminated pollen and nectar
brought into the hive and from chemicals used within the hive, e.g. varroacides. There are no
reports of neonicotinoids in beeswax from colonies
Propolis is collected by bees as resin from trees, e.g. buds, primarily poplars and pine trees and is
used within the hives to block small gaps and as a defense at the hive entrance against ants etc.
and also as an anti-bacterial antifungal agent within the hive. The main propolis plants in Europe
are poplar, birch, oak, alder, willow and hazel. Foragers collect the resin in their pollen baskets to
return it to the hive and can carry approximately 10 mg. The chemical composition of propolis
varies between sources but is a mixture of resins, terpenes and volatiles. Due to the range of
sources of propolis and storage within the hive it can contain a range of contaminants but only a
small number of reports exist of trace residues of pesticides present in propolis collected from
colonies and propolis tinctures prepared from this and no reports of neonicotinoid pesticides
There are three possible sources of inhalation exposure of bees to pesticides. During applications
of pesticides (is a similar manner to flying through spray), through vapour generated from residues
on the crop after application and from stored pollen and nectar within the hive (and potentially
water evaporated within the hive). There are no reports of exposure associated with inhalation of
neonicotinoid pesticide residues.
Neonicotinoid pesticides and bees Page 9 of 133
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