Polymer/Layered Silicate Nanocomposite as Matrix for Bioinsecticide Formulation

Abstract

SummaryDue to current encouragement to the use of bioinsecticides for pest control and the susceptibility of biological agents to external factors, we investigated the use of a polymer nanocomposite (PLN, polymer/ layered silicate nanocomposite) as matrix to encapsulate an entomopathogenic fungus active against pest insects of palm trees. The beads were formed by extrusion and the following variables were assessed: fungus conidial concentration (series 1: 107; series 2: 108 and series 3: 109 conidia/mL) and nanolayered silicate concentration (0; 0.5; 1; 2 and 4%). The matrix was evaluated by X‐ray powder diffraction and Fourier transform infrared spectroscopy and the following characteristics of the products were assessed: percent of encapsulated conidia, size distribution and polydispersity index, swelling index, formulation's in vitro ability to release conidia and stability under different storage temperatures. PLN, whose interactions could be visualized by FTIR, proved to be a potential matrix for this fungus, because, while composed by natural substances non‐toxic to the environment, it succeeded to encapsulate high amounts of conidia (series 2). A barrier effect with bentonite increase was also demonstrated by increased fungus germination time and thermal stability.