Acaricidal efficacy against cattle ticks and acute oral toxicity of Lippia javanica (Burm F.) Spreng.

In search for low-cost, safe and environmentally benign plant-based alternatives to commercial pesticides, the efficacy of Lippia javanica aqueous leaf extracts in controlling ticks on cattle, acute oral toxicity in mice and phytochemistry were evaluated. L. javanica aqueous leaf extracts at 10% and 20% w/v were effective at controlling cattle ticks but not as good as an amitraz-based acaricide Tickbuster. However, they can provide an effective tick control option where synthetic products are unavailable or unaffordable, particularly in remote parts of southern Africa. Peripheral blood samples collected showed no haemoparasites in treated cattle implying that animals did not suffer from clinical tick-borne diseases. The leaf aqueous extracts of L. javanica were tested for toxicity in BALB/c mice. While anecdotal evidence suggests L. javanica has low mammalian toxicity, within 48 h all mice fed with the L. javanica leaf aqueous extract at 12.5-37.5% v/v were lethargic, and overall mortality was 37.5% (n = 24). Thus, despite their apparent safety, water extracts of L. javanica leaves may have deleterious health implications on humans and animals if consumed at very high doses. Many compounds have been identified from L. javanica including an array of phenolic glycosides, flavonoids and essential oils but none of these are known to have acute toxic properties.