Maria Fátima das Graças Fernandes da Silva
Federal University of São Carlos, Brazil
Title: An environmentally friendly procedure to quantify and localize cedrelone in Spodoptera frugiperda after feeding with this limonoid
Biography
Biography: Maria Fátima das Graças Fernandes da Silva
Abstract
Our group investigated the effectiveness and safety of plant extracts as potential natural pesticides for use as possible alternatives for synthetic pesticides that are intensively applied in many plantations in Brazil. In bioassays with ethanol extracts from more than 50 plants, Toona ciliata (Meliaceae) was the most toxic against Spodoptera frugiperda in the lab. Chemical analysis revealed the presence of the active ingredient cedrelone in the stems. It was isolated and assayed against S. frugiperda and evaluated the Cumulative Mortality via the incorporation of this compound into the artificial diet. The activities were comparable to that of the synthetic insecticides. However, its primary modes of action remained unclear. It has been hypothesized that it may inhibit acetylcholinesterase enzyme activity. Cedrelone was observed to cause strong inhibition of the acetylcholinesterase enzyme from S. frugiperda. The purpose of this work was also to apply the mass and nuclear magnetic resonance spectroscopy, a green analytical method which require small amount of solvent, for determination of cedrelone in hemolymph, midgut, head and faeces from S. frugiperda. Cedrelone was detected in the head, intestine and in the excreted faeces. MS spectra showed the presence of intact cedrelone and indicated change in its structure. Quantitative analysis via MS/MS indicated that more than 50% of cedrelone was metabolized. From this study, we conclude that the acetylcholinesterase inhibition is likely the primary mode of action for insecticidal activity by cedrelone.