Identificação e quantificação de hemócitos de fêmeas ingurgitadas de Boophilus microplus inoculados com fungos Metarhizium anisopliae, Beauveria bassiana, Penicillium corylophilum e Fusarium oxysporum. / Identification and quantification of hemocytes obtained from engorged females of Boophilus microplus (Canestrini, 1887) (Acari: Ixodidae) inoculated with Metarhizium anisopliae, Beauveria bassiana, Penicillium corylophilum and Fusarium oxysporum

Sandra Borges da Silva

Biological control of the tick Boophilus microplus with Metarhizium anisopliae and Beauveria bassiana has been evaluated by several researchers. The selection of specimens resistant to chemical products is a mechanism used by arthropods for survival and maintenance in the environment. It is already known how fungi penetrate the host and their pathogenic potential at different phases of their biological cycle, however, ticks immune response against these agents need more detailed studies. The present work had as objectives: to identify and quantify the cellular types involved in the cellular response of B. microplus inoculated with entomopathogenic (M. anisopliae and B. bassiana) and non-entomopathogenic fungi (Penicillium corylophilum and Fusarium oxysporum). In this study 60 engorged females of B. microplus were used, representing six treatment groups with 10 specimens each. Ticks were inoculated with aqueous suspension of conidia. There were two control groups: in the first one ticks were inoculated with Tween 80 0,1% aqueous solution (negative control), in the second one ticks were not inoculated (testimony group). Fungi suspension or Tween 80 solution were applied in the back part of the idiosoma of the tick. The hemolinfa samples were collected during the whole period of life of the specimens, beginning 24 hours after inoculation. The haemolymph samples were fixed in methanol and stained with Giemsa. In all studied periods, cells like pro-hemocytes, plasmatocytes, granulocytes, spherulocytes and oenocytoids were observed in the specimens of all groups. Prohemocytes, plasmatocytes and spherulocytes were the most numerous cells observed in the hemolinfa. Hemocytes were absent in the group inoculated with B. bassiana 72 hours after inoculation. After this period, specimens inoculated with entomopathogenic fungi were dead. The absence of cells suggests the immune-suppressor effect of the fungi on this tick species. It was not observed when ticks were treated with M. anisopliae due to accentuated mortality caused by this fungus species. The nonentomopathogenic fungi did not affect the life cycle of this tick, being quickly eliminated of the organism. It was suggested based on the absence of conidia during sampling.

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