Aspectos biológicos de Boophilus microplus (Acari: Ixodidae) mediante infestações experimentais em eqüinos

Abstract

This work aimed the evaluation of biological parameters of parasitic and non-parasitic phases of Rhipicephalus (Boophilus) microplus (= Boophilus microplus) in equine. Four equines were individually infested with approximately 40,000 larvae obteined of R. (B.) microplus females engorged in bovines, being in two of them established three infestations. In the place of larvae fixation, it was noticed development of an intense itchy reaction and the larvae involved in a serum exudates. A larval mortality of approximately 90% was observed, with a small number of larvae changing to nymph stage. The mortality of nymphs was around 60%, with reduction of the itchy reaction, and in the adult stage was observed approximately 30% of mortality. As for the susceptibility, it was observed that two equine were resistant, one moderately resistant and one sensitive to the establishment of infestation by R. (B.) microplus. In the equine considered sensitive, were made observations of parasitic and non-parasitic phase of this ixodid. According to the parameters of the parasitic phase of R. (B.) microplus, of the three experimental infestations, the day at the beginning of detachment of females occurred among infestations were 28 and 31 days, during 12 days at first infestation and 20 days at second and thirst infestation, presentin modal day at 32º; 36º and 37º day, respectively. Were recovered 179 females of R. (B.) microlus at first infestation, 187 and 358 at the second and thirst infestation, corresponding to a mean recovery rate between 0.90 and 1.79%. The means periods of parasitic phase increase among infestations, during between 33. 27 and 38.51 days, being obteined females with mean weight of 90.0mg at the first infestation, 81.5 mg at second and 109.4mg at thirst infestation, considering all females recovered. For the estudy of the non-parasitic phase were selected form each infestation 20, 49, 71 females, presenting means weights of 151.8; 121.1 and 147.8 mg, respectively. The means periods of pre-posture were between 2.8 and 3.5 days. The means periods of posture were of 13.6; 11.7 and 13.4 days, respectively, with pick of posture occurring at the 3rd day after the beginning at three infestations. The means weights of posture were verified between 57.3 and 80.6mg corresponding to 1,146.9 and 1,611.4 eggs produced. The means periods of incubation of eggs produced by R. (B.) microplus studied females occurred between 23.7 and 29 days, presenting hatch means rates decreasing of 67% in the first infestation to 54.7% at the thirst infestation. The means of reprodutive efficiency index also decreased among infestations of 35.5% to 26.9% at the last infestation. It was verified that the means periods between the infestation date and the beginning of the larval appearance were between 60.0 and 64.9 days. These results demonstrate that, starting from experimental infestation in equine, R. (B.) microplus is able to complete the biological cycle for at least one generation, resulting in a number of larvae enough to infest pastures.