Empirical evaluation of the lone star tick’s theoretical niche through experimentation
Presentation Type
Oral Presentation
Keywords
Invasion, Distribution and Range Limits, Mediterranean Habitat
Department
Biology
Major
Biology
Abstract
In the last 60 years the Lone Star Tick (LST, Amblyomma americanum) has rapidly expanded from its historical southeastern range as far north as Maine and Michigan and as far west as Oklahoma. Although LST has been expanding westward, a recent correlative model predicts a stable western range boundary around central Texas and western Oklahoma due to the dry conditions found west of this region. Despite its generally dry climate, Southern California has several vegetation types, such as riparian woodland and chaparral, which create microclimates that are cooler and more humid than the surrounding areas, and may be suitable habitat for LST. We conducted two experiments to test how climatic factors influence the survival and behavior of LST and thus affect LST expansion into relatively dry areas like Southern California where LST expansion has been considered very unlikely. In the first experiment, we placed adult ticks at four different field sites to assess their survival rate in Southern California microclimates. In the second experiment, we placed adult ticks in questing arenas within environmental chambers set at 40, 35 and 30 ◦C to assess how temperature affects LST questing behavior. In the field experiment, LST survived significantly longer in shaded sites than in sunny sites. We observed a significant difference in relative humidity between shaded and sunny locations, which likely explains why survival rates differed. In the laboratory experiment, LST questing frequency at 40 ◦C was significantly higher than at lower temperatures. Questing height did not change with temperature. Our experiments compel us to reevaluate the theoretical niche of LST
Faculty Mentor
Javier Monzon
Funding Source or Research Program
Academic Year Undergraduate Research Initiative, Summer Undergraduate Research Program
Presentation Session
Session C
Location
Plaza Classroom 188
Start Date
24-3-2017 4:15 PM
End Date
24-3-2017 4:30 PM
Empirical evaluation of the lone star tick’s theoretical niche through experimentation
Plaza Classroom 188
In the last 60 years the Lone Star Tick (LST, Amblyomma americanum) has rapidly expanded from its historical southeastern range as far north as Maine and Michigan and as far west as Oklahoma. Although LST has been expanding westward, a recent correlative model predicts a stable western range boundary around central Texas and western Oklahoma due to the dry conditions found west of this region. Despite its generally dry climate, Southern California has several vegetation types, such as riparian woodland and chaparral, which create microclimates that are cooler and more humid than the surrounding areas, and may be suitable habitat for LST. We conducted two experiments to test how climatic factors influence the survival and behavior of LST and thus affect LST expansion into relatively dry areas like Southern California where LST expansion has been considered very unlikely. In the first experiment, we placed adult ticks at four different field sites to assess their survival rate in Southern California microclimates. In the second experiment, we placed adult ticks in questing arenas within environmental chambers set at 40, 35 and 30 ◦C to assess how temperature affects LST questing behavior. In the field experiment, LST survived significantly longer in shaded sites than in sunny sites. We observed a significant difference in relative humidity between shaded and sunny locations, which likely explains why survival rates differed. In the laboratory experiment, LST questing frequency at 40 ◦C was significantly higher than at lower temperatures. Questing height did not change with temperature. Our experiments compel us to reevaluate the theoretical niche of LST