Effect of the antiparasitic drugs fenbendazole and ivermectin on the soil nematode Pristionchus maupasi.

Abstract

Pristionchus maupasi, a soil nematode, was used to elucidate the potential ecotoxic effect of the two anthelmintics fenbendazole and ivermectin in cattle dung. The population growth of P. maupasi was greater in faeces from cattle harbouring active Panacur- or Ivomec-boli, which are releasing fenbendazole and ivermectin to the rumen, respectively, compared to the growth in control faeces. In dose-response experiments it could be shown that the pure chemical compound of fenbendazole was increasingly nematocidal to P. maupasi in concentrations from 10 to 20 microg/g faeces (ww, i.e. wet weight) and the pure compound of ivermectin was effective above 3 microg/g faeces (ww). The results indicate that neither fenbendazole nor ivermectin have any acute toxic effect on P. maupasi in naturally excreted concentrations of the pure drugs, together with their metabolites in faeces from bolus-treated cattle. Both drugs are excreted in concentrations that are non-toxic to P. maupasi.