Nematodiruslarvae on pasture in coastal Otago

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Abstract
Fluctuations of larvae of Nematodirus spp. on pasture which had been contaminated only in the spring and early summer (November 1962 to January 1963) were studied until May 1964 in the coastal Otago region. Infective larvae were present on the pasture at all times of the year, with greatest numbers occurring during the autumn of 1963, following deposition of the eggs. A peak also occurred during late July and August and a smaller one during November and December. There was no correlation apparent between changes in larval numbers and either minimum grass temperature or hours of bright sunshine. The nature of any seasonal factor influencing the availability of larvae was not evident from a single year''s observations. From a consideration of similar observations carried out in the Wellington district, it appears that climatic differences between that district and coastal Otago are not sufficiently marked to modify the pattern to any great extent. Small numbers of Nematodirus larvae continued to be present on the pasture 70 weeks after the last eggs had been deposited there.