Development and survival of Haemonchus contortus and Trichostrongylus sp. on pasture in Cameroon.

The development and survival of Haemonchus contortus and Trichostrongylus sp. on pasture at Bamenda, Cameroon were studied by spreading faeces containing strongyle eggs from mixed infections on 12 experimental grass plots from April 1988 to March 1989. Development of eggs to infective larvae during the rainy season (April to October) took place within one week. The infective larvae of H. contortus survived for 11 +/- 2 weeks (with a range of 7 to 13 weeks) during this period while those of Trichostrongylus sp. survived for 9 +/- 2 weeks (with a range of 6 to 12 weeks). No larvae were recovered from eggs spread on pasture during the dry season, except in December when unseasonal rains fell within 9 days of spread of the faeces. Rainfall was identified as the most important climatic condition affecting the development and survival of infective larvae on pastures at Bamenda.