Microcápsulas de extrato de Annona muricata L. Annonaceae desenvolvimento, caracterização e aplicação no controle de Plutella xylostella L. Lepidoptera: Plutellidae.

Abstract

The search for alternatives to pest control of agricultural crops is of extreme importance, since these are difficult to control, often requiring the adoption of products with high residual power, becoming a limiting factor for crop management. One of the main factors limiting the production of brassicas is the occurrence of pests, with Plutella xylostella (L.) (Lepidoptera: Plutellidae), a great influence in reducing the commercial value of the species belonging to this botanical group. This study aimed to generate a natural commercial insecticide based on microencapsulated ethanolic extract of Annona muricata L. (Annonaceae) seeds for control of the crucifer's moth, a limiting pest in the production of several species of vegetables. The study was conducted at the Laboratory of Entomology: Alternative Pest Control - CECA / UFAL, in Rio Largo / AL and Natural Resources Research Laboratory of the Institute of Chemistry and Biotechnology and Laboratory of Technology for Drug Control - UFAL, Campus Maceió / AL. The BUCHI Mini Spray Dryer B-290 model with the polymers amido, maltodextrin, gelatin and aerosil was used for the development of the microencapsulate. The characterization was performed through particle size analysis, scanning electron microscopy (SEM) and thermogravimetric studies (TGA). The microencapsulation showed a bimodal behavior with a clear bimodal behavior, with diameters of 0.48 to 79.43 μm and a polydispersity index of 6.414. The SEM showed that the microparticles had both spherical and irregular shapes, with a smooth and rough / wavy, continuous, homogeneous surface, with variable size, and their external surface revealed continuity in the walls, with no apparent cracks, cracks or interruptions being observed. The CLs estimated for the ethanolic extract and the microencapsulated were: CL50 and CL99 of 0.204 and 5.675 mL/L and 0.114 and 4.166 mL/L respectively, with the required ethanolic extract having a higher concentration. Taking into account the residual evaluation in semi-field and field conditions, it is observed that the treatment with CL99MICRO was highlighted as having higher mortalities, on all evaluated days, CL99EXT was the second most efficient and CL50MICRO was higher than the commercial products Azamax and Decis The microencapsulated of A. muricata presented potentialities for the control of caterpillars from 1st to 3rd instars of P. xylostella, both in semi field and field conditions, regardless of the year. In this way, the microencapsulated of the ethanolic extract of the A. muricata seed proved to be efficient to control P. xylostella, presenting a lethal effect and besides residual effect.

Keywords: Diamondback. Graviola. Emulsion. Chemical fractions.