Dear Sirs,

This letter serves as a formal rebuttal to the manuscript entitled “Simultaneous determination of residues in pollen and high-fructose corn syrup from eight neonicotinoid insecticides by liquid chromatography–tandem mass spectrometry” by Mei Chen, Erin M. Collins, Lin Tao, and Chensheng Lu published November 2013 in the journal Analytical and Bioanalytical Chemistry 405(28): 9251–64 (doi:10.1007/s00216-013-7338-7) [1]. The claim that the product flonicamid is a neonicotinoid, and therefore toxic to honeybees and other pollinators, is completely unsubstantiated and incorrect.

According to the Insecticide Resistance Action Committee (IRAC) [2], neonicotinoids are in IRAC Group 4A with the mode of action being nicotinic acetylcholine receptor (nAChR) agonists, requiring strong evidence that action at one or more of this class of protein is responsible for insecticidal effects. This includes the following IRAC subgroups:

  • IRAC Group 4A: Neonicotinoids including acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, thiacloprid, thiamethoxam

  • IRAC Group 4B: nicotine

  • IRAC Group 4C: sulfoxaflor

Flonicamid is a selective homopteran feeding blocker in IRAC Group 9C, and is the only compound in this chemical subgroup. Flonicamid has no effect on the nAChR and according to both the IRAC and the EPA, flonicamid is not a neonicotinoid by classification or mode of action [2, 3].

Furthermore, the EPA-EFED (Environmental Protection Agency – Environmental Fate and Effects Division) has concluded that flonicamid (Beleaf 50SG/Carbine 50WG) has low risk to bees (LD50 > 50 μg a.i./bee) which is confirmed in numerous publications and is widely recognized [3–6]. Therefore, the claim that flonicamid is a neonicotinoid and toxic to pollinators is incorrect.