GRADO DE INFECCIÓN Y MORTALIDAD EN LA GARRAPATA DEL CABALLO Anocentor nitens (ACARI: IXODIDAE) NATURALMENTE INFECTADA POR EL PROTOZOA Babesia caballi (APICOMPLEXA: BABESIIDAE) Infection Degree and Mortality in the Horse Tick Anocentor nitens (Acari: Ixodidae) Naturally Infected by the Protozoan Babesia Caballi (Apicomplexa: Babesiidae)

One hundred and sixty Anocentor nitens infected with Babesia caballi from a horse, naturally infected by B. caballi, were analyzed for the purpose of evaluating both percentage and degree of infection by Babesia caballi, as well as mortality in ticks. Four groups (A, B, C, and D) of 40 females each were conformed . The groups were evaluated at 5, 10, 15 and 20 th days after the natural detachment of the ticks from the host. B. caballi sporokinetes were observed in 49.62% of the ticks. Percentage of infection for the groups A, B, C, and D were 67.5, 55.0, 55.0 and 20.0% respectively. Mortality in the infected ticks reached 85.1, 50.0, 59.1 and 25.0%, whereas in the uninfected ones, the values were 7.7, 50.0, 77.8 and 65.6% for groups A, B, C, and D respectively. The number of B.caballi sporokinetes in the haemolymph decreased during the trial. This fact can be related to the migration of the sporokinetes from the haemolymph to other tissues. The data allows us to confirm the fact that the tick A. nitens is susceptible to parasitism by B. caballi, expressed by adverse effects on the longevity and the reproductive potential of this species.