title: Investigation of activity of monoterpenes and phenylpropanoids against immature stages of Amblyomma cajennense and Rhipicephalus sanguineus (Acari: Ixodidae).
abstract: The objective of this study was to assess the acaricidal activity of carvacrol, thymol, eugenol, and (E)-cinnamaldehyde on unengorged larvae and nymphs of Amblyomma cajennense and Rhipicephalus sanguineus, using the modified larval packet test. Carvacrol, eugenol, and (E)-cinnamaldehyde were tested at concentrations of 2.5, 5.0, 10.0, 15.0, and 20.0 μl/ml, while thymol was tested at concentrations of 2.5, 5.0, 10.0, 15.0, and 20.0 mg/ml, in all cases with 10 repetitions per treatment. For the A. cajennense larvae, mortality rates caused by carvacrol, thymol, eugenol, and (E)-cinnamaldehyde at the lowest concentration were 45.0, 62.7, 10.2, and 81.6%, respectively, reached 100% at the concentration of 5.0 μl/ml for carvacrol and (E)-cinnamaldehyde and 5.0 mg/ml for thymol, while this mortality was observed at 15.0 μl/ml for eugenol. For the nymphs of this species, carvacrol and thymol caused 100% mortality starting at a concentration of 5.0 μl/ml and 10.0 mg/ml, respectively, while eugenol caused 100% mortality at 20.0 μl/ml and the mortality caused by (E)-cinnamaldehyde did not exceed 64%. In the tests with R. sanguineus larvae, the lowest concentration of carvacrol and (E)-cinnamaldehyde resulted in 100% mortality, while this percentage was observed starting at 10.0 μl/ml for eugenol. For nymphs, carvacrol and thymol at the smallest concentration caused 100% lethality, unlike the results for eugenol and (E)-cinnamaldehyde, where 100% mortality was only observed starting at the concentration of 10.0 μl/ml. The results obtained indicate that the tested substances have acaricidal activity on unengorged larvae and nymphs of A. cajennense and R. sanguineus.
authors.affiliation: Pós-Graduação em Ciências Biológicas - Comportamento e Biologia Animal, Universidade Federal de Juiz de Fora, Juiz de Fora, Brasil, tatiosouza@ig.com.br.
authors.forename: Tatiane Oliveira Souza
authors.initials: TO
authors.lastname: Senra
authors.forename: Fernanda
authors.initials: F
authors.lastname: Calmon
authors.forename: Viviane
authors.initials: V
authors.lastname: Zeringóta
authors.forename: Caio Márcio Oliveira
authors.initials: CM
authors.lastname: Monteiro
authors.forename: Ralph
authors.initials: R
authors.lastname: Maturano
authors.forename: Renata
authors.initials: R
authors.lastname: da Silva Matos
authors.forename: Diego
authors.initials: D
authors.lastname: Melo
authors.forename: Geovany Amorim
authors.initials: GA
authors.lastname: Gomes
authors.forename: Mario Geraldo
authors.initials: MG
authors.lastname: de Carvalho
authors.forename: Erik
authors.initials: E
authors.lastname: Daemon
mesh_terms: D056810:Acaricides / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D026863:Ixodidae / Q000187:drug effects*; D007814:Larva / Q000187:drug effects; D039821:Monoterpenes / Q000008:administration & dosage / Q000494:pharmacology*; D020005:Propanols / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D056810:Acaricides; D039821:Monoterpenes; D020005:Propanols