Efeito in vitro do monoterpeno carvacrol sobre estágios não ingurgitados de Amblyomma dubitatum Neumann, 1899 (Acari: Ixodidae)

Abstract

Amblyomma dubitatum plays an important role as an vector of rickettsia in nature. The aim of this essay was to valuate the acaricial activity of the carvacrol on unengorged larvae and nymphs of A. dubitatum. The process of experiments happen through the packet test of larvae and nymphs, being pu in the center of the filter paper, folded in half, closed on the sides with binder clips and moistened with 90 μL of the solution to be tested on each side. The groups were kept in climate-controlled chamber (27±1°C and RH >80±10%) individuals. The concentrations tested were of 2,5; 7,5; 10; 15 e 20 mg/mL, with ten repetitions for larvae and seven for nymphs per treatment. Were formed two control groups for each stage: water and etanol 70% (larvae) and water and DMSO 3% (nymphs). The mortality of unengorged larvae treated with a lowest concentration of carvacrol was 45,7%, being similar statistically (p>0,05) to the control group. The was difference statistic (p<0,05) from the concentration 7,5 mg/mL in relation to group control. The mortality percentual of 100% was obtained from the concentration of 15 mg/mL, but it was statiscally similar (p>0,05) the concentration7,5 mg/mL. For the nymphs unengorged the lowest concentration did't resulted in mortality, reaching mortality percentual of 65,7% in concentration of 20 mg/mL. From concentration of 10 mg/mL there was difference statistic of (p<0,05) in relation the group controle. In the determination of CL50 for unengorged larvae and nymphs were observed values of 2,81 mg/mL and 14,57 mg/mL, respectively. The results obtained indicate that carvacrol has acaricidal activity on unengorged larvae of A. dubitatum.