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

contact LD50 as 445 ng/bee (2119 ng ai/ g bee) at 24 hours, 14.2 ng/bee (67.6 ng ai/ g bee)
at 48 hours and 5.3 ng/bee (25.2 ng ai/ g bee ) at 72 hours. The oral LD50 was 7.1 ng/bee
(33.9 ng ai/ g bee) at 24 hours, 5.3 ng/bee (25.2 ng ai/ g bee ) at 48 hours and 4.6 ng/bee
(22.0 ng ai/ g bee ) at 72 hours.
There is no readily available LD50 data available for acetamiprid but Horgan (2007)
compared the residual toxicity of a 20% formulation of acetamiprid at 100ppm to that of
50ppm imidacloprid and showed that the residue of acetamiprid was safe to B terrestris after
1 days whereas the imidacloprid formulation was still toxic after 3 days.
The toxicity of imidacloprid to the stingless bee N perilampoides (average weight 8.2
mg/bee) showed the contact LD50 after 24 hours was 0.0011 µg/bee (0.0008-0.0015) (0.13
µg/g bee) that of thiamethoxam was 0.004 µg/bee (0.003-0.006) (0.49 µg/ g bee), whereas
thiacloprid was 0.007 µg/bee (0.004-0.01) (0.85 µg/g bee) suggesting that the relative safety
of thiacloprid to honeybees was not reflected by stingless bees (Valdovinos-Nunez et al
2009).
Kumar and Regupathy (2005) reported the toxicity of thiamethoxam and imidacloprid to A
mellifera, A. indica (the Indian honeybee), A. florea (the little bee) and Trigona irridipenis (the
dammer bee) and reported these were similar or less toxic than in A mellifera in the same
laboratory (thiamethoxam 0.0666 µg ai/g bee and imidacloprid 0.0281 µg ai/g bee at 24
hours).
Scott-Dupree et al (2009) assesed the toxicity of imidacloprid and clothianidin to B.
impatiens, M rotundata and Osmia lignaria using treated surfaces. Unfortunately this
prevents assessment of the dose per bee as the LC50 was expressed as a treatment rate
(% solution wt/vol) on the surface of the arena. Based on this they assessed the toxicity
(LC50) of imidacloprid to B impatiens as 3.22 x 10 -3 %, to M rotundata as 0.17 x 10 -3 %, and
to O lignaria as 0.07 x 10 -3 %. The LC50 of clothianidin was B impatiens 0.39 x 10 -3 %, to M
rotundata as 0.08 x 10 -3 %, and to O lignaria as 0.10 x 10 -3 %.
The toxicity of fipronil to A. mellifera, the alfalfa leafcutter bee M. rotundata and the alkali
bee Nomia melanderi was reported by Mayer and Lunden (1999). The LD50 was highest in
N melanderi (1.13 µg/bee; 13.2 µg/g bee), intermediate in A mellifera (0.013 µg/bee; 0.103
µg/g bee ) and lowest in M. rotundata (0.004 µg/bee; 0.132 µg/g bee).
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