Effect of methyl-β-cyclodextrin (MβCD, 2.25 mM) on resistance to thiabendazole (lethal dose 50% or LD₅₀), for each isolate. MβCD treatment increased the LD₅₀ of thiabendazole (TBZ) but the effect was significant only for the two resistant isolates (p < 0.05). The values reported are means ± SD of three replicates. *Significant effect (p < 0.05). Symbols: (grey rectangles) control eggs and (black rectangles) MβCD treatment. HcS-WB: Haemonchus contortus susceptible Weybridge, HcS-Ca: Haemonchus contortus susceptible Canada, HcR-WR: Haemonchus contortus resistant White River, and HcR-G: Haemonchus contortus resistant Guadeloupe.