PS 14-180 - The Effects of Macroparasite Infection on Eastern Box Turtle Movement and Temperature Use

Abstract: Myiasis is a macroparasitic infection caused by flesh fly larvae that grow and feed on the tissue
of living vertebrates. As the wound increases in size from swelling and larval growth, myiasis
may influence the behavior and movement of the host. In ectothermic hosts, not much is known
about how myiasis infection affects temperature use or movement of its host. Recently, myiasis
cases (suspected to be caused by Cistudinomyia cistudinis) have been detected in Eastern Box
Turtles (Terrapene carolina carolina; referred to as EBT) at Joint Base Cape Cod in Barnstable,
Massachusetts. Our objectives were to assess macroparasitism effects on EBT temperature use
and movement. We used radio telemetry to track turtle movement for 13 weeks from May to
August 2022. We tracked turtles weekly and captured 40% of tagged turtles at least seven times.
At each capture, we recorded ambient air temperature as well as the turtle’s location, infection
status, and shell temperature. We used ANOVAs to investigate the relationship of myiasis status
with average distance moved per day and the difference between shell and ambient air
temperature. We found that infected and uninfected turtles traveled similar distances (F-statistic
= 0.694, df = 1, p = 0.406); infected turtles traveled about 10.75 ± 2.29 (mean ± standard error)
m per day and uninfected turtles traveled an average of 12.90 ± 1.34 m per day. Although
infected turtles moved slightly less per day than uninfected turtles, these results suggest that EBT
movement is not significantly affected by myiasis. This conclusion would benefit from further
research with a more comprehensive method of measuring movement and over longer periods of
time. We also found a trend towards infected turtles having a greater difference between shell
and ambient air temperature than uninfected turtles (F-statistic = 3.811, df = 1, p = 0.0522),
where the temperature difference for infected turtles was 4.81 ± 0.74 degrees and the temperature
difference was 3.32 ± 0.38 degrees for uninfected turtles. The larger temperature difference seen
in infected EBT could be attributed to myiasis in EBT being more likely to occur in warmer
microhabitats; or turtles may be moving to warmer microhabitats to regulate temperature in
response to myiasis infection. Future research is needed to explore the myiasis-temperature
relationship and other potential adverse effects of C. cistudinis infection on EBT, which could
help protect this Massachusetts state-listed species of special concern.