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Previous issue date: 2007-02-28 === Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico === 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 32?; 36? and 37? 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. === Este trabalho teve como objetivo avaliar par?metros biol?gicos de Rhipicephalus (Boophilus)
microplus (= Boophilus microplus) mediante infesta??es expermentais em eq?inos. Foram
utilizados quatro eq?inos infestados individualmente com aproximadamente 40.000 larvas,
obtidas de f?meas de R. (B.) microplus alimentadas em bovino, sendo realizadas tr?s
infesta??es em dois destes equinos. No local de fixa??o das larvas notou-se desenvolvimento
de uma intensa rea??o pruriginosa e as larvas envolvidas em um exsudato seroso. Foi
observada uma mortalidade larval de aproximadamente 90%, com um pequeno n?mero larvas
mudando para o est?gio de ninfa. A mortalidade de ninfas ocorreu em torno de 60%, com
redu??o da rea??o pruriginosa, e no est?gio adulto notou-se mortalidade de aproximadamente
30%. Quanto ? susceptibilidade, observou-se que dois eq?inos foram resistentes, um
moderadamente resistente e um sens?vel ao estabelecimento da infesta??o por R. (B.)
microplus. No eq?ino considerado sens?vel, foram realizadas as observa??es de fase
parasit?ria e n?o parasit?ria deste ixod?deo. Em rela??o aos par?metros da fase parasit?ria de
R. (B.) microplus, nas tr?s infeta??es, o dia de in?cio do desprendimento das f?mas ocorreu
entre 28 e 31 dias, durando 12 dias na primeira infesta??o e 20 dias na segunda e terceira
infesta??es, apresentando dia modal no 32?, 36? e 37? dia respectivamente, ap?s as infesta??es
com as larvas. Foram recuperadas 179 f?meas de R. (B.) microplus na primeira infesta??o,
187 na segunda e 358 na terceira infesta??o, correspondendo a uma taxa de recupera??o entre
0,90 e 1,79%. O per?odo m?dio da fase parasit?ria aumentou entre a primeira e terceira
infesta??es, ocorrendo entre 33,27 e 38,51 dias, verificando-se f?meas com peso m?dio de
90,0mg na primeira infesta??o, 81,5mg na segunda e 109,4mg na terceira infesta??o,
considerando-se todas as f?meas recuperadas. Para o estudo da fase n?o parasit?ria foram
selecionadas respectivamente 20, 49 e 71 f?meas de cada infesta??o que apresentaram peso
m?dio, respectivamente, de 151,8mg; 121,1 mg e 147,8mg. Observou-se um per?odo m?dio
de pr?-postura entre 2,8 e 3,5 dias. O per?odo m?dio de postura foi de 13,6; 11,7 e 13,4 dias,
respectivamente, entre as infesta??es, com pico de postura ocorrendo no 3? dia ap?s seu
in?cio. Verificou-se um peso m?dio de postura entre 57,3 a 80,6mg, nas infesta??es, o que
corresponde ? produ??o m?dia de ovos entre 1.146,9 e 1.611,0. O per?odo m?dio de incuba??o
dos ovos das f?meas estudadas de R. (B.) microplus, durou entre 23,7 e 29 dias, apresentando
uma taxa de eclos?o m?dia decrescendo de 67% na primeira infesta??o, para 54,7% na
terceira infesta??o. O ?ndice m?dio de efici?ncia reprodutiva tamb?m decresceu ente as
infesta??es de 35,5%, para 26,9% na ?ltima infesta??o. Verificou-se que o per?odo m?dio
entre a data de infesta??o e o in?cio da eclos?o larval ocorreu entre 60 e 64,9 dias. Estes
resultados demonstram que, a partir de infesta??es experimentais em eq?inos, R. (B.)
microplus ? capaz de completar seu ciclo biol?gico por pelo menos uma gera??o, resultando
em um n?mero de larvas suficiente para infestar parstagens.
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