Thiamethoxam : A neonicotinoid precursor converted to clothianidin in insects and plants

摘要: Neonicotinoid insecticides act agonistically on insect nicotinic acetylcholine receptors (nAChRs). Like imidacloprid (IMI), all neonicotinoids bind with high affinity (I 50 -values ∼ 1 nM) to [ 3 H]IMI binding sites nAChRs. One notable omission is thiamethoxam (THIAM), showing affinities up 10,000-fold less potent than other neonicotinoids, using housefly head membrane preparations. Clothianidin (CLOTHI) exhibits activity as an agonist isolated neurons at concentrations low 30 nM. Pharmacokinetic studies in different species revealed that THIAM was rapidly metabolized CLOTHI, which shows nAChRs both assays and whole cell voltage clamp studies. When applied cotton plants, also quickly metabolized, CLOTHI being the predominant neonicotinoid planta briefly after application, indicated by LC-MS/MS analyses. Our show likely be a precursor for not active itself.