title: 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.
authors.affiliation: Programa de Pós-graduação em Ciências Biológicas, Comportamento e Biologia Animal da Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, s/n - Campus Universitário, Bairro São Pedro, Juiz de Fora, MG, 36036-900, Brazil, laryssa_xa@hotmail.com.
authors.forename: Laryssa Xavier
authors.initials: LX
authors.lastname: Araújo
authors.forename: Tatiane Pinheiro Lopes
authors.initials: TP
authors.lastname: Novato
authors.forename: Viviane
authors.initials: V
authors.lastname: Zeringota
authors.forename: Renata Silva
authors.initials: RS
authors.lastname: Matos
authors.forename: Tatiane Oliveira Souza
authors.initials: TO
authors.lastname: Senra
authors.forename: Ralph
authors.initials: R
authors.lastname: Maturano
authors.forename: Márcia Cristina Azevedo
authors.initials: MC
authors.lastname: Prata
authors.forename: Erik
authors.initials: E
authors.lastname: Daemon
authors.forename: Caio Márcio Oliveira
authors.initials: CM
authors.lastname: Monteiro
mesh_terms: D056810:Acaricides / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007814:Larva / Q000187:drug effects; D048494:Rhipicephalus / Q000187:drug effects*; D013943:Thymol / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D056810:Acaricides; D013943:Thymol