The impact of dehydration and starvation on tick questing behavior

Abstract

By Ethan Revis, Biological Sciences; Kennan Oyen, University of Cincinnati; Joshua Benoit, University of Cincinnati

Advisor: Joshua Benoit

Abstract: The American dog tick, Dermacentor variabilis, is a parasitic and hematophagous arthropod, native to regions of North America lying east of the Rocky Mountains. Similar to other hard-tick species, they have a relatively irregular feeding pattern. As blood feeding animals, they must find a host to obtain a bloodmeal. Between bloodmeals, ticks must survive long periods of starvation. As starvation progresses, ticks may increase their activity levels and questing behaviors to locate a host. Other factors such as changes in humidity will influence tick questing behavior, as ticks (being small in size) are particularly vulnerable to dehydration. However, information regarding how starvation and dehydration influences tick questing behavior is not extensive. As ticks are vectors for several disease-causing pathogens, understanding how abiotic conditions influence questing may provide insights into ticks as disease vectors. We measured the effect of dehydration and starvation on questing times of Dermacentor variabilis at 2 (un-starved) and 6 months (starved) post-ecdysis. Ticks were exposed to either 0% or 93% relative humidity for 24 hours proceeding questing trials. The time required to assume a questing pose was measured for both starved and un-starved ticks exposed to low and high humidity, following a host-cue. Our results show that starvation strongly influences the time to quest, with starved ticks assuming a questing pose significantly faster than un-starved ticks. Dehydration did not influence time to quest estimates for ticks, however, this could be due to the relatively short exposure time. Our results provide insights into the host-seeking behavior of ticks.