MIDGUT OF Rhipicephalus sanguineus SENSU LATO (ACARI: IXODIDAE) FEMALES FED FOR 2 AND 4 DAYS: ACID PHOSPHATASE DETECTION AND MORPHOPHYSIOLOGY OF EPITHELIAL CELLS

Ticks are ectoparasites of medical and veterinary importance. The Rhipicephalus sanguineus sensu lato complex deserves particular attention for its distribution in all the continents, parasitizing mainly the domestic dog as well as man. The primary function of the ticks gut is to conduct and digest blood, and its digestion occurs preferably in the interior of the midgut cells, through the fusion of endosomes and lysosomes, organelles containing hydrolytic enzymes, such as acid phosphatase. The present study detected and posteriorly evaluated the presence of this enzyme in the midgut cells of R. sanguineus s. l. fed for 2 and 4 days on rabbit hosts. The results showed that all the cell types responded positively to the acid phosphatase activity, with variations in intensity and location. Digestive cells showed weak or strong staining, and the generative cells were strongly stained in the 4-day fed. The strong positive staining for acid phosphatase was observed in the different midgut cells, especially in the generative ones (stem cells) that reinforces the multifunctionality of the digestive/secretory cells. In the feeding period of 2 days, it was observed secretory cells in the midgut of the R. sanguineus s.l. females. Thus, the presence of acid phosphatase, both in generative and digestive/secretory cells, places this enzyme as an important target for further studies aiming to find new strategies to control ticks, considering the fundamental role of the midgut in the absorption and digestion of the host’s blood, ensuring the survival of the ectoparasites and their offspring as well (nutrients for the oogenesis).