Dichlorvos

Dichlorvos is an organophosphate insecticide and inhibitor of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE; IC₅₀s = 269 and 44 nM, respectively).¹ It also binds to the M₂ muscarinic receptor in rat heart homogenates.² Dichlorvos is lethal to 4-week old German cockroach (B. germanica) nymphs (LD₅₀ = 0.108 μg per insect) and silkworms (B. mori) in third instar (LC₅₀ = 6.63 mg/L) after 24 hours.^3,4 It is lethal to zebrafish (D. rerio) embryos (LC₅₀ = 39.75 mg/L after 24 hours) and decreases swimming activity of larvae 6 days after fertilization when administered at a concentration of 25 mg/L in tank water.⁵ Dichlorvos (150 ppm for 80 weeks) also increases the incidence of benign and malignant neoplasms in male rats from 47 to 88% as compared to controls.⁶

1.Petroianu, G.A., Schmitt, A., Arafat, K., et al.Weak inhibitors protect cholinesterases from stronger inhibitors (dichlorvos): In vitro effect of tiaprideInt. J. Toxicol.24(2)79-86(2005) 2.Silveira, C.L., Eldefrawi, A.T., and Eldefrawi, M.E.Putative M2 muscarinic receptors of rat heart have high affinity for organophosphorus anticholinesterasesToxicol. Appl. Pharmacol.103(3)474-481(1990) 3.Qian, K., Wei, X., Zeng, X., et al.Stage-dependent tolerance of the German cockroach, Blattella germanica for dichlorvos and propoxuJ. Insect Sci.10(1)201(2010) 4.Zhang, Z.-Y., Wang, D.-L., Chi, Z.-J., et al.Acute toxicity of organophosphorus and pyrethroid insecticides to Bombyx moriJ. Econ. Entomol.101(2)360-364(2008) 5.Si?man, T.Dichlorvos-induced developmental toxicity in zebrafishToxicol. Ind. Health26(9)567-573(2010) 6.Reuber, M.D.Carcinogenicity of dichlorvosClin. Toxicol.18(1)47-84(1981)