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

Table 1. Most publications have concentrated on oral and contact LD50 imidacloprid, but
other neonicotinoids are represented along with imidacloprid metabolites (Table 8); Contact
exposure can be from either of two methods; directly where the dose is applied to the body
of the bee, or indirectly where bees are exposed through contact with a contaminated
surface. All the studies have reported at the effects of neonicotinoids on worker bees and
have concentrated on Apis mellifera and its subspecies; however one study has looked at
toxicity in the Indian Honeybee (Apis cerana indica) (Jeyalakshmi et al., 2011). In general,
LD50 values are lower for oral exposure than for contact exposure, except for acetamiprid
which is the reverse. For imidacloprid this may be explained its low hydrophobicity and poor
penetration through the cuticle (Yamamoto et al., 1995). Residue data undertaken for the UK
Wildlife Incident Investigation Scheme suggests that there is only slow penetration of the
neonicotinoid active ingredients through the cuticle (Figure 1)
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