Invasive Plant Species as Risk Factors for Tickborne Disease in Humans and Livestock: A One Health Approach to Sustainable Agricultural Communities

Participants

Teresa L. Steckler, PhD (PI), IL Extension

Christopher Evans, MS (Co-PI), Department of Natural Resources and Environmental Sciences

Yvette Johnson-Walker, DVM, PhD (Collaborator), Department of Veterinary Clinical Medicine

Christopher M. Stone (Collaborator), Illinois Natural History Survey

Summary

The overall goal of this project is to improve agricultural productivity and safety by increasing our knowledge of the on-farm factors that influence the prevalence of tick-borne diseases.  Ticks are a major vector of human and livestock pathogens that can result in large economic losses impacting the agriculture and natural resource industries as well as lost wages, worker shortages, increased health-care costs, reduced productivity, and chronic disability in workers.  Specifically, we are going to investigate the relationship between different types of invasive plants and the prevalence and diversity of tick species and associated human and animal pathogens.  Understanding this relationship will help in developing recommendations of what practices farmers and landowners can do to lessen the prevalence of tick-borne diseases on the landscape.

Background

Reports of human tick-borne disease (e.g., Lyme disease, spotted fever rickettsioses, babesiosis, and anaplasmosis/ehrlichiosis) cases more than doubled from 2004 to 2016 in the US and this trend of increasing rates of tickborne diseases is also being reported in Illinois.  Recent research has shown that invasive plants can increase risk to human and livestock health by increasing the proliferation of disease-transmitting ticks. Infestations of invasive plant species, particularly woody invasive shrubs, can alter local conditions such as temperature and relative humidity to favor tick survival. However, not all invasive species may have the same effect. The impacts of invasive shrubs on human and livestock risk to tick-borne diseases is likely compounded by high deer densities, which favor the largely browse-resistant exotic shrubs over our more palatable native vegetation, increasing the severity of shrub invasion and allowing for drastic increases in tick populations.

Objectives and Approach

This research will investigate how changes in temperature and humidity due to infestations of invasive plants differ between species and how those changes influence tick populations and tick-borne disease carriage rates.  We will use bush honeysuckle, Japanese chaff flower, and Japanese stiltgrass as our test invasive plant species and use nearby uninvaded areas as a comparison.  Weather stations will be used to monitor climatic conditions and ticks will be collected using drag sampling transects every 3 weeks at each site.  These ticks will be identified to species and tested for the presence of pathogens.

In the long-term this research will serve as the baseline for understanding how invasive plant species influence ticks and tick-borne diseases and will be the foundation for the development of practical recommendations of how to manage and prioritize invasive plants to reduce the health risks related to tick-borne diseases.