ECOLOGY OF THE FREE-LIVING STAGES OF TRICHOSTRONGYLUS-VITRINUS

The ecology of the free-living stages of T. vitrinus was studied in western Victoria [Australia] in 1975-76. Where development of eggs (E1-E2) did occur, preinfective larvae (L1-L2) were recovered within 0-8 days, infective larvae (L3) in (ovine) feces within 10-39 days and on L3 herbage and soil within 4-26 days. The mean development time to L3 on herbage and soil was 12.5 .+-. 4.8 days and the mean development time to maximum yield of these was 37.9 .+-. 9.7 days. The mean percentage of L3 on herbage and soil actually on herbage was 70.8 .+-. 6.5%. L3 persisted in feces for up to 106 days and on herbage and soil for up to 208 days. Yields were highest from those eggs deposited in autumn-winter. No L3 were observed to survive over summer.