Banca de DEFESA: RICARDO DE OLIVEIRA BARBOSA BITENCOURT

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : RICARDO DE OLIVEIRA BARBOSA BITENCOURT
DATE: 15/03/2022
TIME: 13:00
LOCAL: Google Meet
TITLE:

Larvicidal effect of entomopathogenic fungi: interaction, ultrastructural changes and immunological response in Aedes aegypti

KEY WORDS:

biological control, Metarhizium anisopliae, Beauveria bassiana, mosquitoes

PAGES: 97
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SUMMARY:

The thesis aimed to: 1) evaluate and compare the larvicidal effect of blastospores and conidia of B. bassiana CG 206, and M. anisopliae ARSEF 2211 strains; 2) evaluate and compare the larvicidal effect of blastospores and conidia of both fungal strains, combined or not with mineral oil; 3) observe the route of interaction for both fungal propagules combined or not with mineral oil; 4) observe the effect of both fungal strains propagules, combined or not with mineral oil, under larval growth; 5) hemocytes indentification in healthy mosquito larvae; 6) observe the effect of both propagules, under the hemocytes dynamic and quantification in mosquito larvae; 7) comparing the phenoloxidase (PO) activity in larvae exposed to the both propagules of the fungal strains; 8) observe the fungi-hemocytes interaction in mosquito larvae exposed to both fungal strains. Mosquito larvae were immersed in fungal suspensions or emulsions and larval survival was monitored daily for 7 days. Transmission (TEM), scanning (SEM) and histopathology (HP) microscopies of larvae were performed after 24 or 48 hours of exposure. To assess the cellular response and phenoloxidase activity, the larvae were exposed to fungal suspension. The hemolymph was collected for the  hemocytes identification, and total quantification, as well as to perform the hemocytic dynamics and SEM. The PO activity experiments was conducted in supernatant from larvae homogenate. Here, the blastospores and conidia had similar larvicidal activity, being dose-dependent and formulation-dependent (i.e., the larvae were more susceptible to the fungal in higher doses or based-on mineral oil). Both propagules took the digestive tract and respiratory as the route of infection in addition, enterocytes were damaged by the presence of the fungal propagules. The larvae grew more when exposed to blastospores of both strains than the control group, in addition M. anisopliae conidia also induced the larval growth. Prohemocytes, plasmatocytes, granulocytes, adipohemocytes, oenocytoids and thrombocytoids were identified. B. bassiana propagules reduced the hemocytes quantification after 24h, and M. anisopliae affected the hemocytes quantification only 48h post-exposure. In general, the rate of granulocytes, and oenocytoids increased in 24h post-exposure to conidia of B. bassiana. In larvae exposed to M. anisopliae, only the rate of oenocytoids increased in 24h post larval-exposure. Both propagules of the fungal strains increased the rate of the oenocytoids in 48h post larval-exposure; plasmatocytes rate was similar regardless of the time of exposure to both fungal strains. The levels of the PO activity increased in larvae within 48h of exposure to both propagules of B. bassiana or M. anisopliae blastospores. The interaction of hemocytes (such as nodulation) with both fungal propagules, and PO activity increased within 48h of fungal exposure was observed. In conclusion, both propagules of B. bassiana CG 206 and M. anisopliae ARSEF 2211 had potentital as biolarvicide against A. aegypti, and the mineral oil demonstrated to be a candidate develop a fungal formulations. Even after the cellular immune system and PO activity of the larvae were stimulated by the propagules, the fungi were able to interact with the host, mainly through the digestive and respiratory pathways, and reduce the larvae survival.

BANKING MEMBERS:
Presidente - 2860277 - ISABELE DA COSTA ANGELO
Interno - 3701492 - HUARRISSON AZEVEDO SANTOS
Externa ao Programa - 3241766 - MARIANA GUEDES CAMARGO
Externo à Instituição - EVERTON KORT KAMP - UFG
Externo à Instituição - NICOLÁS PEDRINI
Externo à Instituição - JOSE LUIZ RAMIREZ
Externo à Instituição - RICHARD IAN SAMUELS - UENF