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. 2013 Jul 19;83:267–333. doi: 10.1016/B978-0-12-407705-8.00004-5

Table 4.2.

Key features of major trichostrongylid nematodes of sheep and environmental influences on survival

Nematode species Life-cycle stage
Unembryonated egg Embryonated egg Pre-infective larvae Infective larvae
H. contortus High susceptibility to cold and desiccation.
High mortality < 10 °C.		 Susceptible to cold and desiccation.
Low hatching in the absence of moisture and/or < 10 °C.		 High susceptibility to cold and desiccation. Optimum survival under warm and moist conditions.
Poor survival in dry climates (warm or cool) and sub-freezing winter.
T. colubriformis Intermediate susceptibility to cold and desiccation.
High mortality < 5 °C.		 Intermediate susceptibility to cold. Low susceptibility to desiccation. Susceptible to cold and desiccation.
High mortality < 5 °C.		 Optimum survival under warm or cool moist conditions.
Poor survival over sub-freezing winters.
Te. circumcincta Low susceptibility to cold.
Intermediate susceptibility to desiccation.
High egg viability at 0–10 °C.		 Low susceptibility to cold and desiccation.
Hatching < 5 °C.		 Intermediate susceptibility to cold.
Susceptible to desiccation.		 Optimum survival under cool moist conditions and sub-freezing winters.
Poor survival under warm, dry conditions.