Adjacent habitat distribution and management of the lone star tick in Tennessee

Author

Christopher Glenn Morris

Date of Award

12-1999

Degree Type

Thesis

Degree Name

Master of Science

Major

Entomology and Plant Pathology

Major Professor

Reid R. Gerhardt

Committee Members

Jerome Grant, Craig Reinemeyer, Arnold Saxton

Abstract

A six-year treatment program involving the administration of ivermectin to whitetailed deer to manage a population of lone star ticks (LST) implicated in the transmission of Ehrlichia chaffeensis Anderson, Dawson, Jones & Wilson to humans in 1993 was performed in Fairfield Glade, TN, on the Cumberland Plateau from 1994 to 1999. Ehrlichia chaffeensis is the causative agent of human monocytic ehrlichiosis (HME). Two concentrations of ivermectin, 250 mg and 500 mg / 22.7 kg whole kernel corn, were administered from 1994 to 1996 and 1997 to 1999, respectively. Treatment was typically initiated in March and ended in July of each year in compliance with Food and Dmg Administration guidelines.

All free-living LST stages were sampled in the first treatment area (FTA) and non-treatment area (NonTA) from 1994 to 1999. These sites and an additional treatment area (NTA) were sampled from 1997 to 1999. In each of the three areas, three sites were selected, and wooded and open, grassy areas were sampled at each site. Cloth flags (1 m X 1 m were used to sample all free-living LST stages. In addition CO₂ traps (1 m x 1 m) were used to sample adult and nymphal LSTs.

Reductions in all stages of the LST population were observed in the FTA from 1994 to 1996 and the NTA from 1997 to 1999 relative to the NonTA. The effect of the two concentrations of ivermectin was equivalent on male and female LSTs. Natural fluctuations in the LST population and absence of 1999 larval mass data at the time of this publication make this estimate for LST nymphs and larval masses inconclusive.

Comparison of two sampling methods revealed that CO₂ traps placed in wooded habitats during spring captured LST males and females more frequently. Nymphal LSTs were captured more frequently by cloth flags in wooded habitats during summer and early fall. No comparison was possible for larval masses of LSTs, because CO₂ traps were not used to sample them.

Adjacent habitats of woods, ecotone and open, grassy areas were sampled to determine the most likely area one would encounter LSTs. Three sites were selected on the golf course that was the focus of the 1993 HME epidemic and three additional roadside sites were selected in the same area. Lone star tick larval masses were most abundant 5 and 10 m into the woods and nymphs were most abundant 10 m into the woods. No differences were found for LST nymphs and larval masses between golf and roadside sites. Few adults were captured on the six sites which prevented thorough statistical analysis. Fisher's exact test (FET) suggested that males were most abundant in the ecotone of both golf and roadside sites. Females appeared most abundant in the ecotone and 10 m into the woods on golf course sites, but in roadside sites they were most abundant 10 m into the woods.

Recommended Citation

Morris, Christopher Glenn, "Adjacent habitat distribution and management of the lone star tick in Tennessee. " Master's Thesis, University of Tennessee, 1999.
https://trace.tennessee.edu/utk_gradthes/6654