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Table 2 Main features of major trichostrongylid nematodes of sheep and environmental influences on survival; adapted from[28]

From: Impact of gastrointestinal parasitic nematodes of sheep, and the role of advanced molecular tools for exploring epidemiology and drug resistance - an Australian perspective

Nematode species Life cycle stage    
  Unembryonated egg Embryonated egg Pre-infective larvae Infective larvae
H. contortus High susceptibility to cold and desiccation. High mortality at < 10°C. Susceptible to cold and desiccation. Low hatching in the abscence of moisture and/or at < 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 at < 5°C. Intermediate susceptibility to cold. Low susceptibility to desiccation. Susceptible to cold and desiccation. High mortality at < 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 at < 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.