Environmental Engineering Reference
In-Depth Information
Several field trials have been done to assess effects of CPY on citrus on honey
bees (Atkins and Kellum 1993 ). Lorsban 4E was sprayed on unreplicated blooming
1.2 A citrus plots at 2.2 kg ha −1 in the morning or in the evening. Colonies in plots
treated with Lorsban in the morning had “moderate to light” mortality (274 dead
bees over 4 d), with 33% fewer dead bees than colonies in plots treated in the eve-
ning (395 dead bees over 4 d), which was classified as “moderately hazardous”.
This rate of bee deaths is not expected to affect the long-term colony survival and
the authors concluded that Lorsban could be applied to citrus as an evening or early
morning treatment without causing serious honey bee kills.
In a second trial in citrus, honey bee colonies were placed in 10-A plots of
blooming citrus and sprayed in the evening with Lorsban 4E at 1.7 kg ha −1 (Atkins
and Kellum 1993 ). Treatment suppressed visitation by 64% for approximately 2 d
and killed an average of 904 bees colony −1 over 1.5 d, suggesting a moderate to high
overall hazard, based on the expert opinion of the authors. In another trial, unrepli-
cated 2-A (0.81 ha) plots of citrus in full bloom were aerially treated with Lorsban
at 1.7 kg ha −1 in the morning or evening using a helicopter. In contrast to what might
be predicted, the night treatment of CPY was moderately hazardous to bees, whereas
the morning application of CPY was rated as having a low hazard (Atkins and
Kellum 1993 ).
Despite short-term lethal effects on honey bees, colonies should be able to sur-
vive such exposure with few long-term effects. The risk is reduced or eliminated if
application is not made when flowers are open, since CPY is not systemic and is not
translocated to newly opened flowers. Non- Apis pollinators with females that annu-
ally establish nests that are much smaller than that of the honey bee, are likely to be
more sensitive to CPY exposure.
4.4
Other Studies on the Effects of CPY
Toxicity from exposures via beeswax . The potential effect of exposure to CPY
contaminated beeswax on honey bees has not been studied extensively. One
study reported concentrations of 39 pesticides found in frames of brood comb
from hives from the Pacific Northwest, and from colonies provided by the
USDA-ARS honey bee laboratory that were suspected to have died from Colony
Collapse Disorder (Wu et al. 2011 ). Worker bees were reared in brood comb
containing concentrations of known pesticides that were considered to be high,
and in relatively uncontaminated brood comb used as the control. CPY was detected
in some comb samples, but no effects were reported where CPY was present
(Wu et al. 2011 ).
Effects on virus titres . In a study with bee colonies placed in field cages large enough
to allow foraging in a controlled area but still contain the bees, the frequency of
occurrence and titer of viruses in nurse bees, royal jelly, and various life stages of
queen bees reared in colonies fed only almond pollen from trees previously treated
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