Field Trials to Evaluate the Efficacy of Natural Products for the Control of the

Township Of Freehold, Freehold NJ

Investigators

Abstract

Project Summary The Freehold Area Health Department proposes a multi-faceted approach designed to evaluate the efficacy of selected plant-derived natural products to control tick vectors of Lyme disease, the most common tick-borne illness in the United States. Identification of all-natural, low toxicity chemicals extracted from botanical sources that are toxic to nymphal Ixodes scapularis (Objective 1) through comprehensive reviews of pertinent literature and collaboration with the Department of Forest Products, Oregon State University and the Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention (CDC). Nootkatone showed promise in New Jersey field trials and will be the initial plant-derived acaricide (PDA) tested, but other candidate compounds with proven acaricidal activity and practically available quantities from commercial sources adequate for field testing/bioassay within the time frame of the FOA may be added. Formulation of natural products into water soluble or emulsified compounds that can be applied to vegetation and leaf litter in Lyme disease endemic regions (Objective 2) will be addressed through collaboration with Legacy BioDesign, LLC, Loveland, CO and the CDC. Field studies will test a formulation of a nootkatone-based PDA applied against host- seeking nymphal I. scapularis and Amblyomma americanum using two methods (low pressure vs. high pressure hydraulic sprayers) (Objective 3). Combined dragging and walking survey estimates of tick abundance will be compared between treated plots and untreated edge areas to evaluate whether efficacy is due to direct toxicity or spatial repellency (Objective 4). Trials in the second year of the study will test the relative effectiveness of single vs. multiple applications, the efficacy of additional PDAs, and/or testing of different dosage rates and formulations. The third year of the study will examine the potential role of PDAs in an integrated tick management (ITM) program. A comparative cost analysis will be included in the final year of the study. Assessment of the repellent activity of selected PDAs against host-seeking I. scapularis and A. americanum (Objective 5) will be made in field trials comparing repellency of nootkatone and commercially available products containing deet and permethrin. Treated tick drags and coveralls will be exposed along 100-m transects in known tick-infested habitat during the activity periods of all post-embryonic stages of host-seeking I. scapularis and A. americanum. Project Narrative Lyme disease is the most common tick-borne illness in the United States, with over 181,000 confirmed cases reported since 19901 and over 3,372 cases reported in New Jersey during 2005 (representing a case rate of 38.58 cases/100,000 population3 and a 25% increase in cases over that reported in 2004). While conventional chemical control directed against host- seeking ticks has proven to be the most reliable means of suppressing tick populations,16-26 the use of habitat-targeted "hard" acaricides is generally viewed by the public as having undesirable environmental impacts, including adverse health risks on humans and pets, ground and surface water contamination, and effects on non-target organisms.22,27-29 Development of PDAs and all- natural repellents that are effective against both of these medically-important ticks will provide the public and public health agencies alternatives to conventional chemical control as a means of reducing human-tick encounters and the incidence not only of Lyme disease, but the transmission of other emerging tick-borne pathogens.