Banca de DEFESA: ROXANNE MARINA DA SILVA ROQUE

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ROXANNE MARINA DA SILVA ROQUE
DATE: 27/02/2026
TIME: 08:30
LOCAL: Hibrida - Sala Laerte Grisi (GRISIUS-LQEPV) e Google Meet
TITLE:

Action of fluralaner on the reproductive efficiency and hemocyte response of engorged females of Rhipicephalus microplus: standardization of hemolymph collection and in vitro analysis

KEY WORDS:

control; in vitro; cattle tick; isoxazoline; hemolymph.

PAGES: 52
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUMMARY:

The cattle tick Rhipicephalus microplus represents one of the main obstacles to cattle ranching, generating significant economic losses and demanding the intensive use of acaricides, which has led to the selection of multi-resistant populations. Given this scenario, fluralaner, a systemic isoxazoline, emerges as a promising alternative. Considering the central role of hemocytes in ixodid homeostasis, the characterization of their kinetics and viability becomes a fundamental parameter to measure the biological response of these arthropods to exposure to new acaricidal molecules, as outlined in the following assays. The present study aimed to evaluate the effects of fluralaner on the cellular response of engorged R. microplus females, focusing on total count, differential count, and hemocyte viability. Initially, methodological standardization was performed by comparing the total hemocyte count in hemolymph pools and in individual samples. Although no statistical differences were observed in the final cell concentration (4,93 x 106 cél. /mL e 4,73 x 106 cél. /mL, respectively), individual collection showed greater variability. In the differential count, the cell types present in the hemolymph were identified, maintaining the stability of proportions in most treated groups, with the exception of a punctual reduction at the concentration of 0.5 μg/mL at 24 hours. Viability assays using the trypan blue exclusion test demonstrated that fluralaner, at the concentrations and times tested, did not induce immediate cytotoxicity to circulating hemocytes, suggesting that the molecule's mechanism of action on tick reproduction and survival may not be directly linked to primary hemocyte lysis. These results contribute to the cellular understanding of the tick under chemical stress and assist in the validation of experimental protocols for cellular physiology studies in ixodids.

COMMITTEE MEMBERS:
Presidente - 1173660 - FABIO BARBOUR SCOTT
Interno - ***.088.737-** - DIEFREY RIBEIRO CAMPOS - UFRRJ
Interna - 2929889 - THAIS RIBEIRO CORREIA AZEVEDO
Externo à Instituição - GEORGE REGO ALBUQUERQUE - UESC
Externo à Instituição - JOSE RECK JUNIOR - OUTRO