Developmental arrest of Haemonchus contortus larvae in lambs given larval inoculum exposed to different temperatures...

The temperature (15 or 30 C) at which Haemonchus contortus larvae were allowed to develop to the infective (3rd) stage and the temperature at which they were subsequently stored (4, 15, or 30 C) had no effect on the occurrence of developmental arrest (larval impasse) of the larvae in infected lambs. If a large inoculating dose (10,000 larvae) was given to the lambs, a smaller percentage of nematodes was retained (14.2%) then if a small dose (1,000 larvae, 25.8% retention) was given, but the percentage of larvae in developmenttal arrest was greater (7.7% of the retained nematodes vs 0.02%). The temperatures of larval development and storage had no effect on the sex ratio of the adults that developed (46.3% male nematodes).