Designing an Intervention Trial of Human-Tick Encounters and Tick-Borne Diseases in Residential Settings Using 4-Poster Devices to Control Ixodes scapularis (Acari: Ixodidae): Challenges for Site Selection and Device Placement

Abstract

Blacklegged ticks, Ixodes scapularis Say, transmit Lyme disease spirochetes and other human pathogens in the eastern United States. White-tailed deer (Odocoileus virginianus) are key reproductive hosts for I. scapularis adults, and therefore control methods targeting deer have the potential for landscape-wide tick suppression. A topical acaricide product, containing 10% permethrin, is self-applied by deer to kill parasitizing ticks when they visit 4-Poster Tick Control Deer Feeders (hereafter, 4-Posters) Previous 4-Poster intervention studies, including in residential settings, demonstrated suppression of I. scapularis populations but did not include human-based outcomes. To prepare for a proposed 4-Poster intervention trial in residential areas of Connecticut and New York that would include human-tick encounters and tick-borne diseases as outcomes, we sought to identify areas (study clusters) in the 80–100 ha size range and specific locations within these areas where 4-Poster devices could be deployed at adequate density (1 device per 20–25 ha) and in accordance with regulatory requirements. Geographic Information System-based data were used to identify prospective study clusters, based on minimum thresholds for Lyme disease incidence, population density, and forest cover. Ground truthing of potential 4-Poster placement locations was done to confirm the suitability of selected clusters. Based on these efforts, we failed to identify more than a few residential areas fulfilling all criteria for a treatment cluster. We, therefore, reconsidered pursuing the intervention trial, which required inclusion of >30 treatment clusters to achieve adequate statistical power. The 4-Poster methodology may be more readily evaluated in natural or public areas than in residential settings in NY or CT.

Community-based integrated tick management programs: cost and feasibility scenarios

“…While effective against tick species where at least 1 postembryonic stage feeds on deer, 4-Posters are ideally suited for use against A. americanum (Williams et al 2021). However, the use of 4-Posters faces some regulatory constraints, not least concern that the concentration of foraging deer may facilitate disease transmission, as well as habitat damage (Stafford and Williams 2017, Eisen and Stafford 2021, Connally et al 2022). The major disadvantage of all of the host-targeted technologies is that they have an inherent delay in efficacy based on the muti-year life cycles of I. scapularis and A. americanum , but this can be addressed by initially using them in conjunction with other tick control methods having immediate impacts on the ticks (Schulze et al 2007, 2008b).…”

“…Impediments or barriers to implementing ITM programs within residential communities are discussed. These include most homeowners not willing to pay more than $100–150 per year for tick control (Gould et al 2008, Niesobecki et al 2022), reluctance to use effective synthetic chemical control agents (Gould et al 2008, Beck et al 2022), and logistical challenges for the implementation of some control approaches (Stafford and Williams 2017, Connally et al 2022).…”

Operational Considerations for Using Deer-Targeted 4-Poster Tick Control Devices in a Tick-borne Disease Endemic Community

“…Care was taken to place 4-Posters at least 91 m (300 ft) from locations where children may play and therefore not requiring protective fencing around devices 54. The distance between devices was 0.66 to 1.5 km with a theoretical treatment area of 63 hectares or 1 device per 21 hectares (210 000 m 2 ) 40. Per the US Environmental Protection Agency regulations,54 a Connecticut-licensed pest control operator (PCO) installed and maintained the 4-Posters.…”

“…4-Posters attract deer using corn bait, and acaricide is passively applied to feeding deer via treated rollers 29–41. When deployed at a minimum density of 1 device per 20-25 hectares, 4-Posters have demonstrated up to 91% suppression of I scapularis 29,39 and 85% suppression of A americanum 39.…”

“…Tickicide (10% permethrin solution) is the only acaricide currently approved by the US Environmental Protection Agency for 4-Poster use, which can limit device placement due to label restrictions. Previous studies noted challenges to device use, including finding suitable placement locations given regulatory restrictions,39,40 operational and logistical difficulties, damage by wildlife,39,46–48 high costs,46,47,49 concerns about safety to people and animals,41 and reduced efficacy due to alternate food sources 41…”