Presentation Title

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

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Mar 24th, 4:15 PM Mar 24th, 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