Banca de DEFESA: BRUNA REICH MARTINATTI
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.STUDENT : BRUNA REICH MARTINATTI
DATE: 28/03/2024
TIME: 09:00
LOCAL: Videoconferência
TITLE:
Evaluation of Persistence and Larvicidal Activity of the Fungus Metarhizium anisopliae (Metschnikoff, 1879) Sorokin, 1883 in the Control of Aedes (Stegomyia) aegypti Linnaeus, 1762 in artificial breeding sites under semicampo conditions
KEY WORDS:
Entomopathogenic fungus, mosquitoes, biological control
PAGES: 68
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUMMARY:
Aedes (Stegomyia) aegypti is involved in the dissemination of various arbovirus, representing a challenge for Public Health. Faced with increasing resistance to chemical insecticides and concerns about environmental contamination, it becomes crucial to explore more sustainable control approaches. The aim of this study was to evaluate the persistence of Metarhizium anisopliae CG 153 on A. aegypti larvae under semi-field conditions over 3 weeks, following the weekly introduction of a new batch of larvae, and its impact on the offspring, through the adaptation of the World Health Organization's guidelines for laboratory and field testing of mosquito larvicides. Conidia were extracted from rice medium and suspensions were adjusted to 1×106 and 1×108 conidia/mL. Five types of containers, of different sizes and shapes, were used to simulate artificial breeding sites, each type (N=6) containing 100 to 400 mL of conidial suspension or 0.03% Tween 80, with 25 to 100 larvae (L2). Larval survival was assessed daily for 7 days, with a new batch of larvae introduced every 7 days. Virulence persistence was evaluated for 21 days, with a 10 μl aliquot of suspensions taken from the breeding sites every 7 days for conidial viability monitoring and re-isolation. Dead larvae were removed weekly and subjected to fungal re-isolation and scanning electron microscopy. Surviving larvae were removed after 7 days and pupae transferred to cages, where adults emerged and were fed with a 10% sugar solution and blood for oviposition. Eggs were quantified, offspring counted, and their survival assessed daily for 7 days. Temperature and relative humidity were monitored daily. The concentration of 1×108 conidia/mL was the most virulent over the three weeks, reducing almost 100% of larval survival in all types of containers: large pot, significant reduction in larval survival was observed in the first (χ2= 552.5; P<0.0001), second (χ2= 462.4; P<0.0001), and third weeks (χ2= 313.5; P<0.0001); clay pot, significant reduction in the first week (χ2= 609; P<0.0001), as conidial suspensions and 0.03% Tween solution evaporated; small pot, reduction in larval survival in the first (χ2= 263.8; P<0.0001), second (χ2= 496.8; P<0.0001), and third weeks (χ2= 407.5; P<0.0001); flowerpot and small plate containers were monitored for two weeks as suspensions/solutions evaporated. In both, statistical differences were observed in the first (χ2= 1.362; χ2= 350.9; P<0.0001) and second (χ2= 540.7; χ2= 432.8; P<0.0001) weeks, respectively. The average viability of conidial suspensions decreased over the weeks. Fungal re-isolation in treated larvae showed green colonies, characteristic of M. anisopliae. Scanning electron microscopy revealed M. anisopliae conidia on the larvae's cuticle/natural openings. Therefore, M. anisopliae CG 153 was able to persist in artificial breeding sites and maintain its virulence on A. aegypti larvae under semi-field conditions for 21 days, demonstrating potential for bio-prospecting and field application in the biological control of A. aegypti larvae.
COMMITTEE MEMBERS:
Presidente - 2860277 - ISABELE DA COSTA ANGELO
Interna - 2221855 - PATRICIA SILVA GOLO
Externo à Instituição - EVERTON KORT KAMP - UFG
Externo à Instituição - RONALDO ALVES PEREIRA JUNIOR - UFU