Bioatividade e perfil fitoquímico de extratos de Ludwigia spp. sobre Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae)

Abstract

The Brassicaceae family contains numerous plant species used in human food. However, pests such as Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) are responsible for damages that affect productivity in a quantitative and qualitative way. Faced with the evolution of resistance to several synthetic insecticides, the use of botanical extracts has proved to be an alternative for the control of this pest. Therefore, we verified the bioactivity of Ludwigia tomentosa (Cambess.) H. Hara, Ludwigia longifolia (DC.) H. Hara, Ludwigia sericea (Cambess.) H. Hara and Ludwigia nervosa (Poir.) H. Hara, through aqueous and ethanolic extracts, on development, feeding and oviposition of P. xylostella; and we perform phytochemical screening of the extracts. The aqueous extracts of L. tomentosa and L. longifolia prolonged the larval phase and reduced the pupae weight of P. xylostella. L. tomentosa caused higher larval mortality and reduced the fecundity and fertility of P. xylostella eggs, and L. sericea reduced egg viability. From the use of ethanolic extracts, L. tomentosa was responsible for reducing the weight of P. xylostella pupae, and L. sericea negatively influenced egg fertility. The foliar consumption reduced from the use of the aqueous extract of L. tomentosa, while L. longifolia and L. nervosa stimulated larvae feeding. Ethanol extracts were classified as phagodetergent, with the exception of L. nervosa, that was phagostimulant. All extracts were classified as oviposition deterrents in P. xylostella females, regardless of the solvent used. In addition, phytochemical screening showed that the aqueous and ethanolic extracts of the plants contained phenolic compounds, flavonoids, condensed tannins and alkaloids, substances capable of inhibiting food consumption and interfering with the morphology and physiology of larvae, pupae and adults. However, the use of L. nervosa extract is not recommended, as it did not cause significant changes in the development and oviposition of P. xylostella, in addition to being a phagostimulant for the larvae. The extracts of L. tomentosa, L. longifolia and L. sericea caused severe biological alterations, negatively affecting the development, feeding and reproduction of P. xylostella.