Banca de DEFESA: FRANCISCO BERNARDO DE BARROS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : FRANCISCO BERNARDO DE BARROS
DATE: 21/06/2023
TIME: 14:00
LOCAL: PLATAFORMA VIRTUAL GOOGLE MEAT
TITLE:

Insecticidal activity of monkfish seed extracts (Enterolobium contortisiliquum
(VELL.) Morong) on Aedes aegypti (Diptera: Culicidae)

KEY WORDS:

Mosquito vector; plant extracts; Phytochemistry; Secondary metabolites.

PAGES: 69
BIG AREA: Outra
AREA: Ciências Ambientais
SUMMARY:

Synthetic chemical insecticides are the main way to control Aedes aegypti. However, its use has several limitations, including environmental toxicity, risk to human health and selection of insecticide-resistant insect populations. Such factors favor the growing search for natural substances with insecticidal properties. This study evaluated the insecticidal activity of crude extracts of Enterolobium contortisiliquum (Vell.) seeds on eggs and larvae of A. aegypti and verified the phytochemical profile and the presence of lectins in the extract. E. has a wide geographic distribution in Brazil. Its seeds are known for their toxicity, medicinal properties and bioactive proteins, so the extraction of bioactive compounds was performed in 0.15 M NaCl saline solution, due to its ability to solubilize these molecules. To prepare the crude extract, twenty grams of the powder obtained from crushing the seeds were homogenized for 4 hours at 25º, in 200 mL of saline solution. A. aegypti eggs were obtained by capture with ovitrap-type traps. After hatching, the larvae were kept in a B.O.D. (Biochemical Oxygen Demand) with a temperature of 25±1°C, relative humidity of 70±10% and a 12-hour photophase. For tests with eggs and larvae of A. aegypti, the crude extract was used in raw form (Raw Crude Extract - RCE) and boiled (Boiled Crude Extract - BCE) at 100º C for 5 min. Concentrations of 4.68; 9.37; 18.75; 28.13; 37.13 and 46.89 mg/mL, with distilled water as a negative control. Assays were performed in triplicate. Larvicidal activity tests were performed in the B.O.D. The results were submitted to analysis of variance, Shapiro-Wilk Test, Tukey Test and Log-Probit analysis to determine CL50 and 90. The ECB presented better results on the eggs than the RCE, managing to prevent the hatching of the larvae of 81 .66% ± 10.40 of treated eggs, at a concentration of 46.89 mg/mL. Increased concentration improved the ECB's results against eggs. The respective LC50 and 90 were set at 35.95 and 52.67 mg/mL, respectively. In tests with larvae, concentrations of 46.89 and 37.13 mg/mL, for CER and BCE, caused 100% mortality in 24 hours of exposure. Increased concentration improved CER and ECB action. Larval mortality at other concentrations increased with increasing exposure time to 48 h. Concentration (p < 0.001) and time (p < 0.001) are significant factors for the larvicidal activity, as well as the interaction between time and concentration, which proved to be a significant factor for the larvicidal action of the extracts (p < 0.001) . Due to its better total efficiency (E = 72.77), RCE, with 48 h of exposure, is the most promising extract on larvae. 10.86 mg/mL of ROSC after 48 h of exposure is the lowest dose capable of killing 90% of the larvae (CL90). In RCE, the presence of lectins and secondary metabolites: flavonoids, xanthones and phenols, were detected. Lectins and flavonoids have proven action on insects. The results demonstrate the potential of E. contortisiliquum seed extracts in ovicidal and larvicidal action on A. aegypti.

BANKING MEMBERS:
Externo à Instituição - Carlos Henrique Morais de Alencar
Interna - ESTELITA LIMA CANDIDO
Presidente - FRANCISCO ROBERTO DE AZEVEDO