Molecular approaches to studying benzimidazole resistance in trichostrongylid nematode parasites of small ruminants

Molecular techniques are of growing importance in the study of anthelmintic resistance in trichostrongylid worm populations. A knowledge of the geneti c determinants of benzimidazole (BZ) resistance has made it possible to con struct a molecular tool for genotyping individual worms, in respect of muta tion of the beta -tubulin gene responsible for BZ resistance. This tool off ers new possibilities in the diagnosis of BZ resistance, and also in the st udy of anthelmintic use and other breeding management factors that can affe ct the selection of BZ-resistant alleles in worm populations. New molecular methods have also made it possible to study the origin and diversity of BZ -resistant alleles in trichostrongylid populations. The results demonstrate the value of a multidisciplinary approach to the study of anthelmintic res istance, combining molecular, ecological and epidemiological techniques. (C ) 2001 Elsevier Science B.V. All rights reserved.