Eficácia dos extratos vegetais do cerrado contra larvas de Rhipicephalus microplus e Amblyomma sculptum (Acari: Ixodidae)

Abstract

The Cerrado is a rich source of plant biodiversity, offering a potential that has yet to be fully explored for the development of natural products. One of the most promising applications is the control of agricultural pests that cause significant damage to livestock, including the tick Riphicephalus (Boophilus) microplus, which harms cattle farming through its hematophagy process and the transmission of pathogens to host animals, and Amblyomma sculptum, the main vector of Brazilian Spotted Fever, which can cause varying severity in humans and animals and can lead to death. Given the difficulties in controlling these parasites, we designed an evaluation of the larvicidal activity of leaf extracts of Ximenia americana, Piptadenia viridiflora, and Caryocar brasiliense against R. microplus and A. sculptum. Larvae aged 14 to 21 days were exposed to aqueous (AE) and ethanolic (EE) leaf extracts at concentrations of 25, 50, 75 and 100 mg ml-1, with a negative control containing distilled water and a positive control containing synthetic commercial acaricide, with three replicates per treatment. As a result, AE and EE of X. americana, P. viridiflora, C. brasiliense achieved 70% efficacy against R. microplus larvae at concentrations of 25 to 100 mg mL-1. For A. sculptum, the AE and EE of X. americana and C. brasiliense showed 90% efficacy at concentrations of 75 and 100 mg mL-1. The larvicidal activity of the ethanol and aqueous extracts of these plants is attributed to the presence of bioactive compounds such as tannins and flavonoids, identified by high-performance liquid chromatography. The results demonstrated that the extracts, both in water and in alcohol, were highly effective in eliminating tick larvae, especially at higher concentrations, offering a more sustainable and less harmful alternative to the environment compared to synthetic acaricides.