ABSTRACT
The tick Rhipicephalus microplus is a vector of infectious agents that causes great economic loss in the productivity of cattle herds. Several studies have sought natural compounds with acaricidal activity to control ticks, without allowing the development of resistance, without causing environmental damage, and without presenting toxicity to the hosts. The activity of ozone on the natural biomolecules of living beings has been studied as an alternative to control arthropods and acaricidal effects were shown on ticks. The aim of the present study was to assess the acaricidal effect on larvae and engorged females of R. microplus according to ozone dose. Larvae (n = 377) were distributed in 10 groups and engorged females (n = 284) were distributed in 14 groups. One group was used as control (not exposed to ozone) and the other groups were exposed to ozone gas for 5-105 min. Ozone had a dose-dependent acaricidal effect on both larvae and engorged females. Dosages between 355 and 2130 mg/L min had a delayed acaricidal effect (12-180 h), leading to the death of all engorged females before laying eggs, whereas doses between 3195 and 7455 mg/L min showed immediate acaricidal effect (5 min to 4 h). Doses between 1775 and 6390 mg/L min had an immediate (up to 5 min) acaricidal effect on the larvae of this species. Further studies should consider longer follow-up times during the assessment of the acaricidal activity against ticks.
Subject(s)
Acaricides , Rhipicephalus , Female , Animals , Cattle , Acaricides/pharmacology , LarvaABSTRACT
The objective of this study was to characterize macroscopically and microscopically the liver of the collared lizard Tropidurus torquatus, using two adult females and two adult males, captured on the banks of Marambaia Isle in Sepetiba Bay in the state of Rio de Janeiro. Fragments of liver were fixed in Bouins liquid and submitted to routine histological techniques. Sections were cut by a rotary microtome to 5 mm thickness and stained by with HE, PAS, Gomori Trichrome and Gomoris reticulin impregnation. The liver this lizard is a large, speckled dark brown organ composed of a right and left lobe. The gallbladder is located on the visceral surface of the right lobe. The lobules are polyhedral in shape and separated by a thin layer of interlobular connective tissue, forming trabeculae. These contain bile ducts, branches of portal vein and of hepatic artery. The hepatocytes are also polyhedric and have varied sizes. The majority of these cells have nuclei offset toward the periphery, and the cytoplasm is highly vacuolated and was not well evidenced by the histological techniques utilized. The hepatic parenchyma is supported by delicate reticular fibers surrounding hepatocytes and sinusoids. Large quantities of melano-macrophage centers are present in the parenchyma.
