Microencapsulation of Annona muricata L. seed extract for the control of Plutella xylostella

Abstract

Insecticidal plants have stood out in Integrated Pest Management (IPM), associated with other control strategies, and therefore, the development of microencapsulated formulations, which make the active ingredient protected with slow and continuous release, becomes necessary. Thus, the present study aimed to develop, characterize and evaluate the lethal effect of the Microencapsulated Ethanolic Extract (MEE) from Annona muricata L. (Annonaceae) seeds on Plutella xylostella. MEE was developed in a B-290 BUCHI Mini Spray Dryer, using polymers starch, maltodextrin, gelatin and aerosil, and characterization was carried out through microparticle size and humidity, polydispersity index, morphologic analysis, Thermogravimetric analysis (TGA) and scanning electron microscope (SEM). MEE presented particle distribution with evident bimodal behavior, with diameters from 0.48 to 79.43 μm and polydispersity index equal to 6.414. Through SEM analysis, microparticles presented spherical and irregular shape, with smooth and rough/wavy, continuous, homogeneous surface, with variable size and external surface continuous in walls, with no apparent cracks. TGA demonstrated 5 decomposition stages, similar to the ethanolic extract. The estimated Lethal Concentrations (LC) for the ethanolic extract and MEE were: LC50 and CL99 of 0.204 and 5.675 g/L and 0.114 and 4.166 g/L, respectively. It could be concluded that the development of MEE was effective using the spray dryer method, with uniform microcapsules with insecticidal action able to be more soluble and persist the action of the active ingredient for longer times, improving its application in the field.