Direct measurement of dispersal of Dictyocaulus viviparus in sporangia of Pilobolus species.

Dispersal of Dictyocaulus viviparus larvae by Pilobolus sporangia was studied on 29 faecal pats deposited between the end of June and late October 1988. Faecal pats were covered daily from day 3 to 4 after deposition with a large petri dish to measure the numbers of sporangia released and the numbers of larvae carried. The yield of both was variable. Dispersal of lungworm larvae was lowest on over-grazed pasture or when Pilobolus growth was very poor. When faecal pats were sheltered by a long sward, 17 per cent or more of larvae present at deposition were transported in this manner. In July and August, peak dispersal of lungworm larvae was on day 5, in September on day 6 and in October on day 7, the increasing time intervals being probably associated with decreasing temperature.