Impact of Female Humidity Choice on Egg Viability in the American Dog Tick, Dermacentor variabilis

Abstract

By Hannah Mahoney, Biological Sciences; Kennan Owen, University of Cincinnati; Melissa Kelly, Univerity of Cincinnati; Joshua Benoit, University of Cincinnti

Advisor: Joshua Benoit

Presentation ID: 196

Abstract: Exposure to humidity is necessary to maintain water balance and is vital to tick survival and egg viability. In general, ticks prefer damp areas with high humidity, while dry conditions decrease the survival of ticks. Little is known about the detection of humidity in ticks and how this could impact subsequent egg survival. Based on our experiments, we confirm that the Haller's organs are responsible for humidity detection and interference with this appendage alters tick attraction to humidity. This was followed with studies to examine how exposure to low humidity might impact egg viability. Groups of 1, 5, and 50 eggs of Dermacentor variabilis were subjected to different humidities ranging from 33% to 100% and then viability of the eggs was assessed by examining larval emergence. Results show that egg survival decreases with humidity with very few eggs surviving at the lowest humidity (33% RH). The treatment group with a larger number of tick eggs resulted in a greater egg viability at all humidities. In summary, humidity detection is vital to tick egg survival by allowing females to deposit their eggs under favorable conditions. The results of this study can help improve our understanding of D. variabilis's preferred microhabitats, trends in reproduction, and new methods of control.