Molting and Survival of the Brown Dog Tick (Acari: Ixodidae) under Different Temperatures and Humidities1

Engorged larval and nymphal brown dog ticks, Rhipicephalus sanguineus (Latreille), were held at different combinations of constant temperature (10–35°C) and relative humidity (15–95%) for molting. Engorged larvae and nymphs were able to molt (86 and 98% success, respectively) at desiccating conditions (35°C and 35% RH) as well as at all other combinations of temperature and humidity above 10°C. Unfed nymphs were less tolerant of desiccating conditions (35°C and 35% RH) than unfed adults (LT50 = 1.4 weeks survival compared with 6.9 weeks survival) and low temperatures (20°C) and higher humidities (>85%) favored survival of both stages. The tolerance of the brown dog tick for desiccating conditions is a major factor that allows it to live under more arid conditions than the lone star tick, Amblyomma americanum (L.).