Banca de QUALIFICAÇÃO: HAIKA VICTÓRIA SALES MOREIRA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : HAIKA VICTÓRIA SALES MOREIRA
DATE: 28/10/2025
TIME: 13:30
LOCAL: Videoconferência
TITLE:

Development of different in vitro and semi-field control methods for Aedes aegypti using the entomopathogenic isolate Metarhizium anisopliae CG 153

KEY WORDS:

Entomopathogenic fungi, Aedes aegypti, coconut oil, CMC, HPMC

PAGES: 51
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SUMMARY:

Due to frequent arbovirus outbreaks, novel control strategies for Aedes aegypti are crucial. Entomopathogenic fungi have been formulated with adjuvants, such as coconut oil and biopolymers, to enhance their virulence, stability, and ease of application. This research aimed to evaluate the efficacy of formulations based on Metarhizium anisopliae CG 153 against A. aegypti larvae under in vitro and semifield conditions. Initially, the compatibility of the fungus with coconut oil and the polymers carboxymethylcellulose (CMC) and hydroxypropyl methylcellulose (HPMC) was assessed by counting colony-forming units (CFU) and measuring radial colony growth. Subsequently, a physicochemical characterization of the CMC and HPMC biofilms was performed using conformation tests and Scanning Electron Microscopy (SEM). For the in vitro bioassays, coconut oil was tested at of 0.01%, 0.03%, 0.1%, 0.5%, 1%, and 1.5%. Fungal suspensions at 1×106 and 1×107 conidia/mL were then combined with 0.1%, 0.5%, and 1% coconut oil (N=30), and under semifield conditions, a 1×106 conidia/mL suspension was combined with 0.1% coconut oil (N=60). Coconut oil at 0.1% (P=0.0067) and 1% (P<0.0001) increased the number of CFUs compared to the control group. Larvae exposed to 1.5% (χ2=171.4, P<0.0001) and 1% (χ2=79.13, P<0.0001) coconut oil exhibited the greatest reductions in survival. All in vitro fungal concentrations (1×106 and 1×107 conidia/mL), both with and without coconut oil, reduced larval survival more than the control group (χ2=371.5, df=8, P<0.0001). The combination of 1×106 conidia/mL with oil significantly reduced larval survival compared to the fungus alone (χ2=79.26, df=3, P<0.0001). Under semifield conditions, M. anisopliae CG 153, with or without coconut oil, also reduced larval survival (χ2=384, df=2, P<0.0001). Physicochemical analyses revealed bioproducts with a pH around 7.0, a green color in the presence of the fungus, 5 cm of diameter, 0.01 of thicknesses mm, and 0.4 g of average weights. A significant reduction in the swelling degree of HPMC biofilms combined with the fungus was observed. SEM imaging confirmed the presence of intact conidia on the biofilm surfaces. The CMC and HPMC biofilms were tested against A. aegypti larvae (N=60) under in vitro and semifield conditions. The HPMC biofilm was compatible with M. anisopliae CG 153 (P=0.3696), whereas the CMC biofilm was incompatible (P<0.0001) based on CFU counts. A slight difference was also observed after 14 days in the radial growth of colonies for the HPMC (P=0.0104 and P=0.0062) and CMC (P=0.0338 and P=0.0338) groups, respectively, compared to the control. Both CMC (χ2=665.4, df=3, P=0.1110) and HPMC (χ2=501.1, df=3, P<0.0001) biofilms displayed larvicidal activity. The median survival time (S50) for larvae treated with control CMC, CMC combined with M, anisopliae CG 153, control HPMC, and HPMC with M. anisopliae CG 153 CG 153 biofilms was 4, 3, 1, and 1 day, respectively. On the other hand, it was not possible to determine the S50 for the control group. In semifield bioassays, all biofilms showed larvicidal activity compared to the control group (χ2=700.4, df=5, P<0.0001). Notably, the HPMC biofilm with M. anisopliae CG 153 reduced larval survival time to 1 day, the same as the control CMC and CMC with M. anisopliae CG 153 biofilms. Our results demonstrate that these formulations are promising adjuvants to enhance the viability of entomopathogenic fungi as biocontrol agents.

COMMITTEE MEMBERS:
Presidente - 2860277 - ISABELE DA COSTA ANGELO
Interna - 2221855 - PATRICIA SILVA GOLO
Interna - 1700427 - YARA PELUSO CID
Externo à Instituição - GABRIEL MOURA MASCARIN