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Abstract:
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(En)
Examines the proposition that intraspecific differences in characteristics of the non-parasitic stages have evolved as a consequence of exposure to different climatic conditions, and that this indicates the adaptation of Haemonchus contortus populations to local environments. In field studies which defined the seasonal pattern of H. contortus populations on pasture at Albany, Western Australia, both egg development and larval survival were severely limited to dry conditions over summer. However, during s populations in cooler regions such as Albany, where hypobiosis (developmental arrest by parasitic larvae, to escape hostile external conditions) does not occur routinely. It is suggested that cold-tolerance by the free-living stages is an adaptive d
rs to be a significant factor which enables H. contortus to occupy a wide climatic range.
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