Efeito do extrato e da lectina de cladódios de Opuntia ficus-indica (L.) Mill (Cactaceae) na biologia e fisiologia digestiva de Plutella xylostella (L.) (Lepidoptera: Plutellidae)

Abstract

Plants produce a wide variety of metabolites that are linked to defense mechanisms. These organic compounds may exhibit a potential insecticide and have become an important alternative to the use of insecticides. The chemical defense mechanism of plants also includes the production of proteins. The objective of this study was to investigate the effect of cladodes extract of Opuntia ficus-indica (forage palm) on the biology (survival, fertility and oviposition behavior) of Plutella xylostella (Lepidoptera: Plutellidae) and determine if lectin active principle of the extract. Extracts of cladodes were evaluated on the activity of digestive enzymes; structural organization and intestinal histochemistry of P. xylostella larvae are described. The results showed that O. ficus indica extract contains lectins (specific hemagglutinating activity: 178), and secondary matabolites such as flavonoids, cinnamic derivatives, terpenes, steroids and reducing sugars. The viability of P. xylostella eggs (33%) was significantly reduced (F =11.34, P <0 001) by the cladode extract at 7.2% (m / v) when compared to the control group (95%). When first-instar larvae were treated with the extract at 7.2%, the results showed a significant reduction (F4,45 = 11.32; P <0.0001) of the percentage of larvae (53.00%) that reached the pupal phase in relation to the control (80.00%). OfiL did not modify the viability of larvae and pupae. However, lectin and cladode extract caused inhibition of protease activity in larval gut, epithelial disorganization, and increased expression of neutral carbohydrates and proteins.