Assessing the Impact of Nano-Encapsulated Repellent Application to Cattle Ears on Rhipicephalus Appendiculatus Infestation

Abstract

East Coast Fever (ECF), also referred to as theileriosis, is a tick-borne disease caused by Theileria parva, posing substantial challenges to livestock farming and food security in numerous developing nations. The primary transmitter of ECF is Rhipicephalus appendiculatus. Previous studies have indicated that adult R. appendiculatus tend to feed predominantly around and within the ears of their hosts. Through a combination of a repellent blend from the anal region and an enticing blend near the ears, researchers have identified inherent "push" and "pull" mechanisms that steer ticks towards their preferred feeding sites. Initial research utilizing a crude repellent blend from the anal region resulted in tick confusion, prompting many to detach from the cattle. Further investigations revealed 4-methylguaiacol as the primary compound in bovine anal odor, demonstrating strong repellent properties against R. appendiculatus. Study of 4-methylguaiacol analogues identified 4-propylguaiacol as the most potent variant. Comparative analysis of the release rate of 4-propylguaiacol in ethylcellulose, polyvinylpyrrolidone, and β-cyclodextrin revealed β-cyclodextrin microcapsules as the most efficient. The aim of this research was to evaluate on-host the effect of microcapsules of 4-propylguaiacol polymers towards tick infestation and to assess their duration of protection. 0.5g of the microcapsules was tagged to one and two ears of the bovines respectively. The ticks were released from different body parts, and their behavior was assessed. Application of the treatment to both ears ensured 100% protection for seven days, showcasing superior efficacy compared to single-ear application. The β-cyclodextrin complex demonstrated a protracted "push" effect, effectively repelling ticks over an extended duration. These findings indicate the potential of the complex as a valuable tool in safeguarding cattle against brown ear ticks.