Oral delivery of the systemic acaricide moxidectin to a confined Odocoileus virginianus (Artiodactyla: Cervidae) herd parasitized by Ixodes scapularis (Ixodida: Ixodidae).

This study evaluated efficacy of oral delivery of the systemic acaricide moxidectin to a confined, wild, white-tailed deer (Odocoileus virginianus Zimmermann; WTD) herd in late fall, when adult blacklegged ticks (Ixodes scapularis Say) are known to actively seek hosts in the northeastern United States. Moxidectin-treated corn was dispensed using timed-release feeders at a fenced study site in Connecticut during fall 2021 and 2022. White-tailed deer were captured and sampled four times each year to measure moxidectin levels in sera and assess adult I. scapularis burdens. Results documented that oral moxidectin delivery achieved sufficient dosing for targeting I. scapularis. Mean moxidectin concentrations in sera samples (11.7 ppb when detected) were at or above minimum lethal threshold to kill parasitizing ticks (5-8 ppb) in 66% of captured deer (n = 33) when treated feed was available. Use of timed-release feeders purposefully reduced overall corn consumption by an average of 40% compared to traditional ad libitum 4-poster device strategy, presumably minimizing intraspecific competition from hierarchical feeding behaviors as well as non-target consumption and excessive caloric supplementation. This study demonstrates that fall deployment of moxidectin-treated corn using timed-release feeders can be an effective and efficient method for the systemic treatment of WTD contributing to integrated tick management strategies for reducing tick-borne disease risk while minimizing caloric input.