Biocidal activity of the extracts of Vernonia amygdalina against ticks responsible for livestock diseases

Abstract

Biocidal activity of Vernonia amygdalina was assessed on Rhipicephalus appendiculatus ticks responsible for livestock diseases in North and South-Kivu provinces. In vitro trials were conducted in the laboratory of Lwiro Research Center for Natural Sciences to determine the lethal dose for different days after ticks contact with extracts. Five different dosages of 1.25, 2.5, 5, 10, 20 g/mL were evaluated. Water was considered as positive control and Batycol as negative control. The phytochemical screening of extracts of Vernonia amygdalina plant shows that this plant contains several substances responsible for acaricidal activity, mainly saponins, terpenoids, steroids and tannins. The experiment shows a mortality rate that varies with the concentration of the extracts; the most fatal is 20 g/mL and decreases with exposure time. The aqueous extracts showed a progressive decrease in mortality compared to ethanol extracts. This is due to the dissolution of the substances responsible for this insecticidal activity. The study recommends the application of aqueous extracts of Vernonia amygdalina in the fight against cattle ticks. Indeed, this is a natural insecticide available and easier to prepare, non-toxic to humans and is rapidly degraded in the environment.