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THIABENDAZOLE RESISTANCE IN FIELD POPULATIONS OF HAEMONCHUS CONTORTUS
Author(s) -
Jambre L.F. LE,
Martin P.J.,
Webb R.F.
Publication year - 1979
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.1979.tb15263.x
Subject(s) - haemonchus contortus , biology , veterinary medicine , strain (injury) , resistance (ecology) , anthelmintic , zoology , helminths , ecology , medicine , anatomy
SUMMARY: Six populations of H. contortus were selected for a study of thiabendazole resistance from a collection of 40 populations made during a survey of the efficiency of thiabendazole on the Northern Tablelands of New South Wales. Based on survey results, 3 of these populations were considered susceptible and the remaining 3 were considered resistant. However, when these populations were compared with a known susceptible strain on the ability of their eggs to hatch in a solution containing thiabendazole and 0.1% NaCI all 6 had significantly greater LC 50 'S. The resistance ratios of the LC 50 for each of the 6 populations to that of the known susceptible strain were 5.1, 4.3, 3.2, 3.1, 2.3 and 1.6 respectively. Following dosing of their host with 44 mg/kg thiabendazole the resistance ratios of the survivors increased to 5.4, 5.1, 4.7, 4.4, 3.1 and 2.4. Eggs produced by the F 1 generation of the worms surviving 44 mg/kg thiabendazole did not revert back to the lower LC 50 's of the unselected parents. Rather the LC 50 remained at a level near that of a known highly resistant strain of H. contortus .