Acaricide and ovicide activities of thymol on engorged females and eggs of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

Abstract

The present work had the objective of evaluating the influence of different concentrations of thymol on the biological parameters of engorged females of Rhipicephalus (Boophilus) microplus and also its ovicide activity on eggs of this tick. In order to carry out the work, four groups were formed, each containing 20 engorged females, which were immersed for 5 min in different concentrations of thymol (1.0%, 1.5%, and 2.0%) and a control group (water + dimethylsulfoxide). The following biological parameters were observed: initial weight (mg); egg mass weight (mg); pre-oviposition, oviposition, and survival period (days); hatching percentage (%HP); egg production (%EPI) and nutritional (%NI) indexes; and the percentage of control (%C). In order to perform the second stage, thymol solutions were sprayed on the egg masses (50 mg). The parameters' initial weight and pre-oviposition did not present significant differences (p>0.05) among the groups. Thymol caused alterations in the parameters egg mass weight, oviposition, survival period, hatching percentage, EPI, and NI, presenting highly significant differences between the treatments and the control group (p<0.01). The control efficacy was higher than 95% in all the treatments, reaching 99% in the concentration of 2.0%. In the ovicide test, the hatching percentage was not affected in any of the treatments (p>0.05). In the second experiment, when eggs were treated directly, the thymol did not affect significantly this parameter. These results demonstrate that thymol showed deleterious action on most of the analyzed parameters; thus, it is possible to conclude that, in laboratorial conditions, this monoterpene was efficient in the control of engorged females of R. (B.) microplus.

Toxic and repellent activity of selected monoterpenoids (thymol, carvacrol and linalool) against the castor bean tick, Ixodes ricinus (Acari: Ixodidae)

“…Thymol and carvacrol are strictly biogenetically correlated monoterpene phenols (Dall'Acqua et al, 2017), with molecular formula C10H14O, occurring in essential oils from aromatic and medicinal plants such as oregano (Origanum vulgare L.), thyme (Thymus vulgaris L.), savory (Satureja montana L.) and ajwain (Trachyspermum ammi (L.) Sprague) where they constitute the major oil fraction (Vitali et al, 2016;Benelli et al, 2017;Morshedloo et al, 2017;Nabavi et al, 2015). Both carvacrol and thymol were reported to have broad acaricidal activity against a number of arthropod pests of medical and veterinary importance (Barimani et al, 2016;Concepción et al, 2013;Senra et al, 2013;Tabari et al, 2015;da Silva Mendes et al, 2011;Daemon et al, 2009;de Oliveira Monteiro et al, 2009;de Oliveira Monteiro et al, 2010;Masoumi et al, 2016). Linalool is a linear monoterpene alcohol, with molecular formula C10H18O, reported to be the main volatile component of the essential oils of several aromatic species such as lavender (Lavandula angustifolia Mill.…”

Histopathological changes in the liver and thyroid of mice (Mus musculus) caused by the acaricides: fipronil and thymol

“…Among the chemicals extracted from plants, thymol is a volatile monoterpene present in the essential oils of Apiaceae, Lamiaceae and Verbenaceae plants and has acaricide action when applied to different stages and species of ticks [19]. Thymol chemical structure contains a hydroxyl group that enables permeability to the cell membrane and causes damages to the cells and tissues, killing ticks [20].…”

“…Thymol chemical structure contains a hydroxyl group that enables permeability to the cell membrane and causes damages to the cells and tissues, killing ticks [20]. Also, thymol have been proven to be efficient and less harmful to the environment and nontarget organisms [19].…”

“…Thymol, obtained from Sigma-Aldrich with 99% purity, in formulations, at the concentration of 2%, via dilution in hydroethanolic solution at 30% (v/v), based on the lethal concentration for R. (Boophilus) microplus [19].…”

The role of flavor and fragrance chemicals in TRPA1 (transient receptor potential cation channel, member A1) activity associated with allergies

“…Thymol is a well-known naturally occurring chemical with strong biological activities, including antibacterial [ 71 ], larvicidal [ 72 ], anti-inflammatory [ 73 ], nematicidal [ 74 ], acaricide [ 75 ], antifungal [ 76 ] and antioxidant [ 40 ] activities. When TDI-sensitized rats were exposed to vapor phase thymol, various biological effects, including sneeze suppression, inhibition of an increase of calcitonin gene-related peptide, and appearance of nerve growth factor in nasal lavage, were observed [ 77 ].…”