Evaluation of methanol extracts of Zanthoxylum alatum as a topical repellent against terrestrial leech (Haemadipsa montana) in rabbits

Abstract

In the present study, methanolic extracts of Zanthoxylum alatum fruits prepared into petroleum jelly-based ointments were evaluated for its leech repellent effect on New Zealand white rabbits. A widely prevalent terrestrial leech species of the humid forest areas, Haemadipsa montana, known to parasitise animals and humans, causing blood loss, skin irritation, and secondary infections in animals due to prolonged bleeding from bite wounds, was used for the study. There exist concerns regarding long-term use of synthetic leech repellents for environmental safety and toxicity. Plant-based repellents provide a promising alternative because of traditional use and eco-friendliness. Three concentrations of the extract at 10%, 20%, and 30% (w/w) incorporated into ointments were investigated on 20 rabbits randomly distributed into five groups, including a negative (plain petroleum jelly) and a positive (19% DEET ointment) control. Abdominal fur of the rabbits was shaved, and test ointments were applied. Ten terrestrial leeches per rabbit were then allowed to attach onto the prepared site and attachment behaviour, time to attachment, feeding success, and post engorgement weight were recorded. Results showed that the methanolic extracts had a dose-dependent leech repellent effect against H. montana. The highest concentration (30%) showed best repellence. No adverse skin reactions were noted in any treatment group. These findings support the efficacy of Z. alatum extracts as effective leech repellents. The study validates the traditional use of the plant and suggests its potential for developing natural, safe, and sustainable topical repellents for veterinary use.