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Fitness of benzimidazole-resistant and -susceptible worms of Teladorsagia circumcincta, a nematode parasite of small ruminants

Published online by Cambridge University Press:  01 December 1998

L. ELARD
Affiliation:
INRA, Station de Pathologie Aviaire et de Parasitologie, 37380 Nouzilly, France
C. SAUVE
Affiliation:
INRA, Station de Pathologie Aviaire et de Parasitologie, 37380 Nouzilly, France
J. F. HUMBERT
Affiliation:
INRA, Station d'Hydrobiologie Lacustre, BP 511, 74203 Thonon Cedex, France

Abstract

We compared, some fitness-related traits of benzimidazole resistant (rr) and susceptible (rS, SS) worms of Teladorsagia circumcincta, a gastrointestinal parasite of the small ruminants, under laboratory conditions. PCR was used to determine the genotypes (rr, SS, rS) and the fitness of each was compared within the same strain. There was no significant difference in egg production, development rate from egg to infective larvae stage, establishment of these larvae in the host or the survival of adult worms and infective larvae for the 3 genotypes. The same results were obtained for the establishment rate of larvae in the host and the production of infective larvae under conditions of strong competition between resistant and susceptible worms. The fact that there were no differences in fitness suggests that the installation of benzimidazole resistance in a worm population is irreversible. This agrees with field observations.

Type
Research Article
Copyright
1998 Cambridge University Press

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