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Abstracts - Sonia Cristina J Gualtieri

INSECTICIDAL ACTIVITY OF FRACTIONS AND COMPOUNDS ISOLATED FROM LEAVES OF TITHONIA DIVERSIFOLIA (HEMLS.) A. GRAY AGAINST Spodoptera frugiperda (J. E. SMITH)

Maria Augusta F.M.Miranda*, Paula Novaes2, Andreia P Matos3, and Sonia Cristina J Gualtieri4

  1. UFSCar; gutaagro@yahoo.com.br

  2. USP; paulanovaes.botanica@gmail.com UFSCar; aprereiramatos@gmail.com

  3. UFSCar; aprereiramatos@gmail.com

* UFSCar; Correspondence: soniacristina3012l@hotmail.com

The search for insect pest control methods based on natural products has become an alternative to conventional control. Therefore, this work aimed to evaluate the toxicity of the ethyl acetate fractions of Tithonia diversifolia leaf extract on Artemia salina and their insecticidal effect against the fall armyworm, Spodoptera frugiperda. We evaluated the toxicity of fractions A (20% MeOH), B (40% MeOH), C (60% MeOH) and D (80% MeOH) and E (100% MeOH) and the compounds tagitinin A, tagitinin C and 1β-methoxydiversifolin, isolated from fraction A, at the concentrations 1000, 500, 250, 150 µg.mL-1 on Artemia salina. The EtOAc fractions and compounds, dissolved in DMSO, were added on microplate containing A. salina and after 24 h of incubation at 25 ° C were performed to estimate the percentage of death. Most tested fractions and compounds showed toxicity to A. salina. Fraction C was more toxic (LC50 = 308.8 μg.mL-1), followed by the fraction B (LC50 = 439.1 μg.mL-1) and the fraction A (LC50 = 481.2 μg.mL -1). The lowest LC50 values ​​were obtained for compounds 1β-methoxydiversifolin (185.5 μg.mL-1) and tagitinin C (293.8 μg.mL-1). The most active fractions and compounds were further tested on S. frugiperda. Therefore, the fractions were incorporated in artificial caterpillar food at 100 mg.Kg-1 and the compounds at 100, 50, 10 and 5 ppm. S. frugiperda larvae were added to test tubes containing artificial food + extracts or the controls (MeOH or only the artificial food, as positive controls). We evaluated the length of larval and pupal stages, pupal weight and mortality in the larval and pupal stages (%). A significant reduction was observed in the caterpillar pupal mass at the fraction A, compared to the control containing only the artificial food, indicating a suppressive effect of caterpillars feeding caused by this fraction. Fractions B and C yielded a significant difference in the larval caterpillar stage, and the fraction C increased the duration of larval stage at 2.03 days. In the presence of the compounds, especially 1β-methoxydiversifolina, the larval stage was reduced compared to the two positive controls. Other parameters were not affected by the tested compounds.

Refs.

1. Miranda, M. A. F. M. et al. Phytotoxins from Tithonia diversifolia. Journal of Natural Products, 2015. (Published online: april 2015). DOI: 10.1021/acs.jnatprod.5b00040