Insecticidal and growth inhibiting action of the supercritical extracts of Melia azedarach on Spodoptera frugiperda

This study evaluates the effects of supercritical carbon dioxide extracts obtained from the fruit of Melia azedarach L. (Meliaceae) on the development of Spodoptera frugiperda J.E. Smith, 1797 (Lepidoptera: Noctuidae), from the larval period until the insect adulthood. For this purpose, a laboratory-scale extraction unit was operated at 60 °C and 200 bar. Larval mortality increased by raising the extract concentration tested: the value of LC50 calculated by Probit analysis was 376.74 mg kg-1, and at a concentration of 5000 mg kg-1, the mortality was 100%. The extract exhibited insect growth inhibitory activity in the higher concentrations (500 mg kg-1, 1000 mg kg-1 and 5000 mg kg-1), due to antifeedant action, resulting in larvae and pupae with mass and body length significantly smaller than the control. At the lowest concentration tested (100 mg kg-1), bioactive effects from the adult stage of the insect were observed, with low viability pupal and adults presenting morphological deformities, hence indicating chronic toxicity effect. Ação inseticida e inibitória de crescimento de extratos supercríticos de Melia azedarach sobre Spodoptera frugiperda