Óleos essenciais e terpenos como estratégia de controle de carrapatos e nematoides

Abstract

Ticks and nematodes are widely distributed parasites of veterinary importance. The continuous use of synthetic acaricides and anthelmintics has resulted in increased resistance. Thus, therapeutic alternatives such as natural products have been considered. The parasitic activity of plant essential oils (EOs) and their components have been investigated against ticks and nematodes. This study aimed to evaluate essential oils and terpenes as a strategy to control nematodes and ticks. The action of essential oils (EOs) obtained from 16 cultivars of Ocimum basilicum, linalool, methyl chavicol, citral and eugenol was evaluated in vitro in the test of inhibition of the hatching of eggs of the nematode Haemonchus contortus. Additionally, the action of three cultivars was evaluated, which were simulated using a combination of the two main compounds of each one. For the tick studies, a shampoo containing carvacrol was formulated with sodium lauryl ether sulfate, cocoamidopropyl betaine, lauryl glucoside, carboxymethyl cellulose, methyl paraben and citric acid. The shampoo's sensory characteristics and pH were evaluated at 37, 25 and 5 °C. The effectiveness of shampoo containing carvacrol against R. microplus and R. sanguineus was evaluated by the larval immersion test. Regarding the tests on nematodes, the EOs from different cultivars of O. basilicum showed a concentration to inhibit 50% of the hatchability of eggs (IC50) of H. contortus, ranging from 0.56 to 2.22 mg/mL. The cultivar with the most significant inhibition of egg hatching, napoletan, consists mainly of linalool and methyl chavicol. Among the individual compounds tested, citral was the most effective (IC50 0.30 mg/mL). The best combination of compounds was obtained with 11% eugenol and 64% linalool (IC50 0.44 mg/mL). As a result of the assessments on ticks, the mortality of R. microplus and R. sanguineus was 100% after treatment with 0.15% shampoo containing carvacrol (1:19 dilution of shampoo in water). The shampoo with carvacrol was stable under the conditions analyzed. We conclude that different cultivars of O. basilicum have different efficacies against H. contortus, with the cultivars containing linalool and methyl chavicol being the most promising; we also conclude that the shampoo containing carvacrol has acaricidal efficacy and is a potential tick control agent.