Induction of traps byOstertagia ostertagilarvae, chlamydospore production and growth rate in the nematode-trapping fungusDuddingtonia flagrans

Abstract

AbstractBiological control of parasitic nematodes of domestic animals can be achieved by feeding host animals chlamydospores of the nematode-trapping fungusDuddingtonia flagrans. In the host faeces,D. flagransdevelop traps that may catch nematode larvae. In experiments on agar,D. flagranshad a growth rate between 15 and 60 mm/week at temperatures between 20 and 30°C. The presence of nematodes induces the fungus to produce traps. The rate of trap formation inD. flagranshas an optimum at 30°C, producing 700–800 traps/cm2/2 days, when induced by 20 nematodes/cm2on agar. Approaching 10 and 35°C the ability to produce traps is gradually reduced. The response of chlamydospore production on agar to changes in temperature is the same as that for trap formation. On agar, at 10, 20 and 30°CD. flagransloses its trap inducibility after 2–3 weeks. During the ageing process, increasing numbers of chlamydospores are produced up to a certain limit. The time for reaching maximum chlamydospore concentration coincided with the time for loss of induction potential. The implications of these results in relation to biological control in faeces are discussed.