Activation of Organophosphorus Insecticides in the Central Nerve of Larvae of Spodoptera litura(Lepidoptera : Noctuidae)

Abstract

An O-ethyl S-propyl phosphorothiolate insecticide, TIA-230, is oxidatively activated in the central nerve of an insect to inhibit its acetylcholinesterase (AChE), and shows strong insecticidal activity. Activation experiments of various TIA-230 substituents and other organophosphorous insecticides were carried out in the isolated nerve cord of larvae of Spodoptera litura. Phosphorothiolates having O-ethyl S-propyl or O-ethyl S-butyl group were strongly activated in the nerve cord and showed potent insecticidal activity. Phosphorodithioates having O-ethyl S-propyl group and O, S-dimethyl phosphorothioates were not activated though they showed strong insecticidal activity. In these chemicals, activation sites other than the nerve tissue must function to exhibit AChE inhibition.