The effects of temperature and humidity on Rhipicephalus sanguineus survival

Rhipicephalus sanguineus Latreille, the brown dog tick, is able to establish populations both indoors and outdoors. Indoors, ticks are not always visible to residents due to small size and development in refugia. Residents may think the infestation is eliminated until ticks reappear after molting and start questing. Early in residential infestations, each tick stage may appear synchronously. Later, synchrony breaks down and multiple tick stages are visible simultaneously. This may result from different developmental and survival times of brown dog ticks under variable residential environmental conditions. Brown dog ticks can survive for long periods when hosts are not available. The survival times of unfed ticks vary among life stages and are affected by environmental factors, such as temperature and humidity. In this study, larval, nymphal, and adult survival times of three brown dog tick strains were evaluated under environmental combinations of five temperatures and four humidities. Survival times were recorded weekly and were analyzed by fitting survival models followed by assessing differences between treatments in model parameters. Primary results indicated that tick survival was sensitive to both temperature and humidity. Adult lifespans were longest at low temperatures and high humidity. Larvae at low humidity had the shortest survival time. The results will be used to develop an individual-based model to improve our understanding of phenology and visibility of brown dog ticks during residential infestations.