Moisture Stress Effects on Survival of Infective Trichostrongylus colubriformis Larvae

Water was evaporated from infective Trichostrongylus colubriformis larvae suspended in tap, distilled, and triple-distilled water, and the nematodes were then exposed to 50% and 70% relative humidity (RH) at 20 and 30 C. Sample groups were rehydrated for 4 h daily in similar quality water, observed for motility and counted, then returned to the same RH and temp and re-desiccated. Desiccation and rehydration were repeated until all motility ceased. Longest survival was 30 days at 20 C and 70% RH. In all temp and RH combinations, control (nondesiccated) and desiccated larvae survived longer in distilled or triple-distilled water than in tap water.