Banca de DEFESA: GUILHERME MOTA MACIEL DO REGO BARROS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : GUILHERME MOTA MACIEL DO REGO BARROS
DATE: 25/02/2025
TIME: 09:00
LOCAL: Banca híbrida - LQEPV/DPA/IV/UFRRJ - https://meet.google.com/omx-aehs-bnn
TITLE:

Molecular and Toxicological Characterization from Ctenocephalides felis felis to Fipronil. 

KEY WORDS:

parasitic resistance; ectoparasites; phenylpyrazole; endosymbiont

PAGES: 48
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUMMARY:

The flea is an important ectoparasite that can cause diseases in domestic animals. Ctenocephalides felis felis is the most common species found in these animals, and Fipronil, a phenylpyrazole, acts on chloride channels activated by GABA (gamma-aminobutyric acid), leading to flea death through hyperexcitation. Given the potential for Fipronil resistance in C. felis felis, it is necessary to monitor this issue. Thus, the objective of this study was to characterize, through bioassays, the susceptibility of C. felis felis to Fipronil in a laboratory strain. Additionally, the study aimed to detect the possible presence of mutations in the Rdl (Resistance to Dieldrin) gene in both a laboratory strain and a field strain. Another objective was to investigate the presence of Rickettsia felis, an important bacterium for veterinary medicine, whose primary host is C. felis felis. For the laboratory strain, lethal concentration (LC) values were determined for C. felis felis, with LC50 at 10.39 ppm and LC90 at 23.71 ppm. Molecular analyses revealed that 94.73% (36/38) of the fleas from the laboratory strain were homozygous for the resistance mutation in the Rdl gene. In the field strain, the same genotype was found in 90.83% (109/120) of the fleas. Furthermore, 5% (6/120) of the fleas from the field strain were heterozygous for the mutation, while 4.16% (5/120) were homozygous for alleles without the resistance-associated mutation. The presence of R. felis DNA was detected in 94.73% (36/38) of the fleas from the laboratory strain and in 27,50% (33/120) of the fleas from the field strain. Compared to other toxicological studies, the laboratory colony was characterized as susceptible to Fipronil, despite the predominance of the resistance genotype in the Rdl gene. In the field strain, this genotype was also predominant. Based on these results, it can be concluded that the Rdl gene mutation alone is not sufficient to confer resistance to Fipronil in C. felis felis. In this study, the presence of R. felis may have played a role in the susceptibility of C. felis felis to the insecticide. Additionally, it was observed that this mutation is predominant in both laboratory and field flea populations.

COMMITTEE MEMBERS:
Presidente - 2929889 - THAIS RIBEIRO CORREIA AZEVEDO
Interno - ***.088.737-** - DIEFREY RIBEIRO CAMPOS - UFRRJ
Externa ao Programa - ***.783.337-** - TASSIA TORRES FURTADO - UFRRJ
Externa à Instituição - ROVANIA LAUREANO DOYLE
Externo à Instituição - LIVIO MARTINS COSTA JUNIOR