[The effect of different strains Babesia bovis (Babes, 1888) on tick of Boophilus microplus (Canestrini, 1887)]. / Efeito de diferentes amostras de Babesia bovis (Babes, 1888) em carrapatos Boophilus microplus (Canestrini, 1887).

Two samples (modified and no-modified) of Babesia bovis, were used to evaluate the effect on engorged females of Boophilus microplus Babesia spp - free. For so much, were used three holstein breed bovine, males with 6 months of age, (BH1, BH2 and BH3), coming of the Plateau of Itatiaia, Rio de Janeiro, Brazil. Each calf was infested with 0.2g of B. microplus larvae Babesia spp- free, for 10 consecutive days. They were inoculated in the calves BH1 and BH2, modified and no modified sample, respectively. After natural fall of adults ticks from the vertebrate host, 100 engorged females of each host (BH1, BH2 and BH3) were incubated in BOD, with superior Relative Humidity up 80%, Temperature of 28 degrees C, were appraised daily until the 12th day post incubation (dpi.). In the group of the engorged females obtained of calf BH1, infection of ticks was not observed, to the haemolymph exam and oviposture. The sporokinets absence in these samples was related with the successive passages in splenectomized calves and the criopreservation of the sample. In engorged females from BH2 it was observed rates of infection of 100% and 82% of mortality in 7th dpi. and 100% until 12nd dpi., as the oviposture, 70% did not make oviposition and 30% made it until 7th dpi.

[Morphologic characterization and biological aspects of evolutive forms of Babesia bigemina (Smith and Kilborne, 1893) (Protozoa: Babesiidae) in Boophilus microplus (Canestrini, 1887)]. / Caracterizçã morfológica e aspectos biológicos das formas evolutivas de Babesia bigemina (Smith; Kilborne, 1893) (Protozoa: Babesiidae) em Boophilus microplus (Canestrini, 1887).

The development of Babesia bigemina in Boophilus microplus were studied in experimental conditions, using crossed-breed bovine from free-area of these parasites. Stages of the hemoparasites were observed in the tick vector, starting from the infected red-blood cells observed in the gut of engorged females, from the first 24 hours after detachment to the emergence of sporokinets in the larvas. In the period from 24 to 48 hours after detachment of the engorged females (DEF), the presence of some infected red-blood cells was verified, beside the occurrence of ray bodies and of vermiculars forms, known as oocynets. Since 72 hours after the DEF, the of okinets presence was observed in the cytoplasm of the epithelium cells besides of great sporokinets number in development. At same period, the presence of sporokinets of B. bigemina in the hemolymph samples was observed inside the hemocytes. After the fourth day of incubation beside the presence of the sporokinets was also verified in the Malpighi's tubes and ovaries. As well as in the ticks eggs from the sporokinets were also observed ticks eggs from the fourty day after the natural detachment of the engorged females of the host.