Action of pesticides on earthworms. Part I: The toxicity of cholinesterase‐inhibiting insecticides to earthworms as evaluated by laboratory tests

Abstract

AbstractThe action of seven cholinesterase‐inhibiting pesticides [aldicarb, carbaryl, carbofuran, oxamyl, paraoxon (diethyl 4‐nitrophenyl phosphate) parathion and trichloronate], the organochlorine insecticide, gamma‐HCH, and the nematicide potassium N‐hydroxymethyl‐N‐methyl(dithiocarbamate) (PHMD) on four earthworm species was investigated by laboratory toxicity tests. Eisenia foetida was the most tolerant species to the pesticides tested. Aldicarb was the most toxic pesticide to this species, causing severe dehydration prior to death or at sublethal concentrations. Aldicarb was also toxic to the other species (Allolobophora caliginosa, A. chlorotica and Lumbricus rubellus), while oxamyl, the other oxime carbamate, was not toxic to any of them. Carbaryl and carbofuran at low concentrations were lethal to A. caliginosa, A. chlorotica and L. rubellus, but E. foetida could tolerate high concentrations without dying, although low concentrations severely affected its ability to work the soil or to disappear from the soil surface. Paraoxon, parathion, trichloronate and gamma‐HCH were moderately toxic with low lethal effect to all species. The ability to work the soil was moderately affected by parathion, trichloronate and gamma‐HCH. PHMD was toxic to all the species. The lethal and non‐lethal effects of the pesticides are discussed in relation to their possible biochemical mode of action in earthworms, and the data are compared with published information from field trials.