Banca de DEFESA: JULIE RHANNA TAVARES FERREIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : JULIE RHANNA TAVARES FERREIRA
DATE: 27/10/2021
TIME: 09:00
LOCAL: Internet - Zoom
TITLE:

Histopathological analysis and lipid profile of Rhipicephalus microplus ovaries submitted to treatment with Beauveria bassiana and Eugenol

KEY WORDS:

Biological control, Cattle tick, essential oils, entomopathogenic fungi.

PAGES: 97
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Doenças Parasitárias de Animais
SUMMARY:

Rhipicephalus microplus tick has a significant impact on Brazilian cattle raising, being responsible for economic losses estimated at 3.24 billion dollars per year. Excessive use of chemical acaricides leads to tick resistance, in addition to affecting non-target organisms and the environment. Entomopathogenic fungi and essential oils have been shown to be effective in controlling bovine ticks. Here, the effect of the isolate of Beauveria bassiana CG 479 and the plant compound eugenol, alone or combined at different concentrations, against bovine ticks were evaluated. Initially, the germination rate of B. bassiana was evaluated at 1 × 10⁶ con/mL combined or not with eugenol at 0.18 mg / mL or 0.75 mg / mL. Regardless of the dose, eugenol was not able to reduce fungus germination. As well, the impact of both bioagents on the biological and reproductive parameters of engorged females of R. microplus were analyzed. Bioassays were conducted according to Bennett (1974), as a result, B. bassiana at 1 × 10⁸ con/mL combined with eugenol at 0.18 mg / mL or 0.75 mg / mL demonstrated the best control potential as well, how it reduced all reproductive parameters by about 50%. For evaluation by light microscopy, the ovaries of female ticks (24 and 72 hours after exposure to the fungus and/or eugenol) were collected and stained with hematoxylin and eosin, and histopathological analysis was performed to identify the morphological changes in the tissues ovaries. In general, regardless of time, oocyte vacuolization, pedicel hypertrophy and disorganization of oocyte membranes were observed in ovaries of R. microplus females exposed to B. bassiana at 1 × 10⁸ con/mL combined with eugenol at 0.18mg/mL or 0.75 mg/ml. Ovarian lipid profile was evaluated by thin layer chromatography according to Bligh & Dyer (1959) and Angelo (2013). The results obtained demonstrate that fatty acid and cholesterol were only affected by B. bassiana combined with eugenol at 72 hours post-exposure. The changes caused in reproductive parameters, such as the 47.5% reduction in total posture, which led to a control percentage of up to 56.48%, can be explained by the changes observed in the ovaries and lipid profile of treated females, and demonstrate the potential of the entomopathogenic fungus combined with eugenol as an alternative to control bovine ticks and reduce the reproductive efficiency of R. microplus.

 

BANKING MEMBERS:
Presidente - 2860277 - ISABELE DA COSTA ANGELO
Interna - 1282902 - KATIA MARIA FAMADAS
Interna - 2929889 - THAIS RIBEIRO CORREIA AZEVEDO
Externo ao Programa - 058.965.206-03 - CAIO MÁRCIO DE OLIVEIRA MONTEIRO - UFG
Externa à Instituição - RENATA SILVA MATOS - UFSCAR