Systematic Review on the Use of Natural Products for Ectoparasite Control in Ruminants.

Introduction: Ectoparasites, including ticks, lice, fleas, and flies, represent a major challenge in livestock production because of their negative impact on animal health and their role as vectors of infectious diseases. Current control strategies mainly rely on synthetic ectoparasiticides; however, their extensive use has promoted the emergence of resistant strains and raised concerns regarding environmental safety and food quality. In this context, plant-derived compounds have attracted increasing attention as sustainable alternatives for ectoparasite management in ruminants. Therefore, this systematic review aimed to evaluate the efficacy of plant-based products against ectoparasites affecting ruminants.

Methods: A comprehensive literature search was performed in the PubMed database, including studies published between January 1993 and June 2023, using keywords related to phytochemicals, ectoparasites, and livestock species. Studies were selected according to predefined inclusion and exclusion criteria.

Results: A total of 615 records were identified, of which 66 studies met the inclusion criteria. Most studies focused on ticks (47/66), followed by flies (14/66) and lice (5/66), with the majority conducted in vitro (59/66). Publications increased markedly after 2014, reflecting growing interest in sustainable ectoparasite control. Overall, 136 plant species from 42 botanical families were evaluated, mainly essential oils and extracts, particularly from the Lamiaceae and Asteraceae families. Tea tree oil, cinnamon, and lemon eucalyptus showed notable insecticidal or repellent activity, likely related to bioactive terpenes and alkaloids. Plant-based products demonstrated promising activity against flies and lice, whereas efficacy against ticks was more variable, with only 45% of studies reporting ≥80% effectiveness. Repellent activity was generally short-lived.

Conclusions: Plant-derived products represent a promising strategy for sustainable ectoparasite control in livestock systems. However, further studies are needed to improve the standardization, efficacy, and field applicability of these compounds before large-scale implementation in veterinary practice.