Acaricidal activity of plant-derived essential oil components against Psoroptes ovis in vitro and in vivo

Abstract

Background Treatment of Psoroptes ovis in cattle is limited to topical acaricides or systemic treatment with macrocyclic lactones. Treatment failure of macrocyclic lactones has been reported. The aim of this study was to evaluate a potential alternative treatment against P. ovis . Methods The acaricidal activity against P. ovis of four plant-derived essential oil components, i.e. geraniol, eugenol, 1,8-cineol and carvacrol, was assessed in vitro and in vivo . In vitro contact, fumigation and residual bioassays were performed. In addition, 12 Belgium Blue cattle were artificially infested and treated topically once a week for three successive weeks with carvacrol in Tween-80 (treatment group) or with Tween-80 alone (control). The efficacy of carvacrol was determined by the reduction in lesion size and mite counts. Six additional animals were topically treated with carvacrol to assess local adverse reactions. Results Three components showed a concentration-dependent acaricidal activity in a contact assay, with LC 50 of 0.56, 0.38 and 0.26% at 24 h for geraniol, eugenol, and carvacrol, respectively. However, 1,8-cineol showed no activity at any of the tested concentrations in a contact bioassay. In a fumigation bioassay, carvacrol killed all mites within 50 min after treatment, whereas geraniol, eugenol and 1,8-cineol needed 90 to 150 min. Following a 72 h incubation period in a residual bioassay, carvacrol killed all mites after 4 h of exposure to LC 90, while geraniol and eugenol killed all mites only after 8 h exposure. Based on these results, carvacrol was further assessed in vivo . Mite counts in the treatment group were reduced by 98.5 ± 2.4% at 6 weeks post-treatment, while in the control group the mite population had increased. Topical application of carvacrol only caused mild and transient erythema 20 min after treatment. No other side effects were observed. Conclusions Considering the strong acaricidal activity of carvacrol in vitro and in vivo and the mild and transient local side effects, carvacrol shows potential as an acaricidal agent in the treatment of P. ovis in cattle.

Nematicidal activity of essential oils of medicinal plants

“…No less relevant are the studies on the effect of essential oils on the vitality of Acari in the environment. Chen et al (2019) described the mortality level of Psoroptes ovis (Hering, 1838), mites, sheep parasites, exposed to four components of essential oil of plant origin (geraniol, eugenol, 1,8-cineole and carvacrol). A. suum, egg 0.0 ± 0.0 0.0 ± 0.0 -"-", effect of essential oil from plant on vitality is absent; < 0.001, reliability of differences between the control values and plant preparations according to ANOVA.…”

“…Currently, data on use of essential oils from medicinal plants against different stages of parasites and agricultural pests are appearing with increasing frequency. These oils are applied in different concentrations, both in vitro and in vivo (Kweka et al, 2011(Kweka et al, , 2012Rey-Valeirón et al, 2017;Chen et al, 2019;Martynov et al, 2019aMartynov et al, , 2019bZhou et al, 2019). Most often research focuses on mortality of parasites after exposing them to solutions of essential oils with exposure ranging 24-72 h. Lethal concentrations of essential oils, as well as exposure to their effective action against insects and Acari pests of agriculture and ectoparasites have been studied.…”

A value-added application of eugenol as acaricidal agent: The mechanism of action and the safety evaluation

“…Due to the volatileness, with the extension of treatment time, the concentration of eugenol was decreased, and the complex I was released. This hypothesis also explained the reason why the different tests existed the significant different acaricidal activity [12] , [13] , [14] . As Chen et al [12] claimed, the inconsistency of the results would be attributed to the different experimental design.…”

“…This hypothesis also explained the reason why the different tests existed the significant different acaricidal activity [12] , [13] , [14] . As Chen et al [12] claimed, the inconsistency of the results would be attributed to the different experimental design. In our assay, mites were placed into dishes to incubate with eugenol.…”

“…Eugenol (4-allyl-2-methoxyphenol), a major component of essential oils of several plants in the family Myrtaceae [5] , has attracted the attention of researchers with its remarkably broad spectrum of activities [6] , [7] , [8] , [9] , [10] . Recent studies have shown that eugenol and its analogs exhibit significant antiparasitic activity against various parasites in both humans and animals (includes cattle and rabbits), such as Leishmania infantum chagasi , Psoroptes ovis and Psoroptes cuniculi [11] , [12] , [13] , [14] . Knio et al reported that eugenol exhibited larvicidal activity against Ochlerotatus caspius [15] by reducing the mitochondrial membrane potential as shown in isolated rat liver mitochondria [16] .…”