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

.
24 hr contact et al 2009
The lowest LD50 reported for each study are shown in Table 6 for contact toxicity and Table
7 for oral toxicity. These data suggest that the contact toxicity is generally within an order of
magnitude of the A. mellifera for imidacloprid and thiamethoxam whereas N perilampoides is
several orders of magnitude more sensitive following contact exposure to thiacloprid. Table 7
shows the toxicity of oral exposure to acetamiprid but this should be interpreted with care as
the exposure profile differed significantly with the Bombus species exposed ad libitum to
treated sucrose for 48 hrs and Apis only for 2-4 hrs. .
Table 6: Summary data using lowest contact LD50 for each reported study (µg/g bee)
imidacloprid
thiacloprid
A
mellifera
(India)
B A
T
N
terrestris
0.025indica
A florea irridipenis perilampoides
0.19 0.036 0.077 0.53 0.13 0.028 0.81
A
mellifera
thiamethoxam 0.082 0.191 1.34 0.49 0.066 0.24
Table 7: Summary data using lowest oral LD50 for each reported study (µg/g bee)
4 hrs access
to treated
48hrs access to treated sucrose
sucrose
Neonicotinoid pesticides and bees Page 27 of 133
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0.85
B ignitus B hypocrite B patagiatus Bterrestris A mellifera
acetamiprid 0.01 0.013 0.01
Conclusions
0.022-
0.095 145
In general, LD50 values are lower for oral exposure than for contact exposure, except for
acetamiprid which is the reverse; this may be explained by low hydrophobicity and poor
penetration through the cuticle of these compounds. The chloronicotinyl insecticides
(thiamethoxam, clothianidin, imidacloprid) are more toxic than the cyano substituted
(thiacloprid, acetamiprid)
The oral toxicity of imidacloprid, which has been extensively reported within the literature; is
highly variable with 48 hour oral LD50 values ranging from 3.7 to as high as 400 ng/bee.
including bumble bees, other Apis species and non-Apis species.
Data across pesticides generally suggests that the toxicity to Apis mellifera reflects that in
other bee species when it is expressed on a weight basis and is supported by data for the
chloronicotinyl insecticides but there are far less robust data for the cyano substituted
neonicotinoids.
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