An endogenous rhythm of trap formation in the nematophagous fungus Arthrobotrys oligospora.

In the predacious fungus Arthrobotrys oligospora Fres., the number and distribution of traps formed after the addition of living nematodes to the colonies were determined. At 21°C the traps were formed periodically; the mean period was 42.3±0.8 h. The periodicity was independent of light-dark (LD) cycles of 24 h (10:14). Temperature influenced the hyphal elongation but did not affect the periodic trap formation; at lower temperatures the peaks of trap formation were close together, showing partial overlapping. Induction of rhythmic mycelial growth and conidiation by chemical means was effective only in LD-cycles. The latter diurnal rhythm was weakly correlated with the trap formation and did not affect the endogenous period of approximately 42 h.