Acaricidal activity of thymol against larvae of Rhipicephalus microplus (Acari: Ixodidae) under semi-natural conditions

Abstract

This is the first study to investigate the activity of thymol on Rhipicephalus microplus larvae under semi-natural conditions. For this purpose, tests were conducted in pots with Brachiaria decumbens seedlings containing cattle tick larvae. Thymol, diluted in ethanol 50° GL, was tested at concentrations of 2.5, 5.0, 10.0, 15.0, and 20.0 mg/mL, along with the control group treated with the solvent alone. Each treatment was composed of five pots (1 pot = a repetition). The experiment was performed in three steps. On the first day, the larvae were applied at the base of the signalgrass. Twenty-four hours later, approximately 25 mL of the solution was applied with thymol on the top of the vegetation in each pot. The survival of the larvae was measured 24 h after application of the solutions. Each pot was analyzed individually, and the grass fillets contained larvae were cut with scissors, placed in Petri dishes, and taken to the laboratory to count the number of living larvae. At the highest concentrations (10, 15, and 20 mg /mL), the number of live larvae declined by more than 95 % in relation to the control group. The lethal concentration 50 % (LC50) and LC90 values were 3.45 and 9.25 mg/ml, respectively. The application of thymol in semi-natural conditions starting concentration of 10 mg/mL significantly reduced the number of living R. microplus larvae.

Acaricidal efficacies of Lippia gracilis essential oil and its phytochemicals against organophosphate-resistant and susceptible strains of Rhipicephalus (Boophilus) microplus

“…A plant identified to have acaricidal properties against the SCFT is Lippia gracilis Schauer (Verbenaceae), which is found in well-drained, semi-arid regions of northeastern Brazil where it is produced on a large scale (Pessoa et al, 2005;Cruz et al, 2013). The essential oil of L. gracilis has high content of carvacrol and thymol, which are toxic to the SCFT (Cruz et al, 2013;Senra et al, 2013;Araújo et al, 2015). However, the spectrum of acaricidal activity by L. gracilis essential oil, or its major constituents carvacrol or thymol against SCFT that are resistant to commercially available acaricides remains to be determined.…”

Pharmacological Properties and Molecular Mechanisms of Thymol: Prospects for Its Therapeutic Potential and Pharmaceutical Development

“…Thymol possesses antibacterial (Didri et al, 1994), antifungal (Mahmoud, 1994), anti-inflammatory (Aeschbach et al, 1994), antioxidant (Yanishlieva et al, 1999), anti-mutagenic (Zahin et al, 2010), larvicidal (Pavela, 2009), analgesic (Ozen et al, 2011), anti-microbial (Karpanen et al, 2008), acaricidal (Araujo et al, 2015), anticonvulsant, antiepileptogenic (Sancheti et al, 2014), wound healing (Riella et al, 2012), anti-hemolytic (Alinezhad et al, 2013), antiphlogistic (Anamura, 1989), antileishmanial (Robledo et al, 2005) and radioprotective (Archana et al, 2011a) properties. Thymol improves digestion by relaxing smooth muscles, prevents menstrual cramps, attenuates respiratory problems and is an active ingredient used in food flavorings, topical ointments, various soaps, toothpastes, shampoos, deodorants and mouthwashes (Shapiro et al, 1994; Manou et al, 1998).…”

Biocidal potential of Eugenia pyriformis essential oil in the control of Rhipicephalus (Boophilus) microplus in the free-living cycle

“…(B.) microplus larvae, reducing more than 95% the number of live larvae (Araújo et al 2015), thus indicating the efficiency of the protocol established by this author.…”

“…Essential oil activity on Rhipicephalus (Boophilus) microplus. Acaricidal activity of "uvaia" EO was determined by the adult immersion test (AIT) (Drummond et al 1973) and the larval packet test (LPT), recommended by the Food and Agriculture Organization (FAO 2004), whereas larvicidal activity was verified in the free-living cycle (Araújo et al 2015).…”