Insecticidal fungal metabolites fabricated chitosan nanocomposite (IM-CNC) preparation for the enhanced larvicidal activity - An effective strategy for green pesticide against economic important insect pests

Abstract

In the present study, enhanced pesticidal activity and biocompatibility of chitosan nanocomposite prepared with biocompatible polymer chitosan - insecticidal metabolites derived from potential fungal biopesticidal agent Nomuraea rileyi were studied. Insecticidal metabolites were isolated from the culture filtrate of fungal strain grown in sabouraud maltose yeast extract broth (SMYB) and the collected filtrate was extracted with ethyl acetate followed by purification using G-60 silica gel column. Chitosan nanocomposite was prepared with metabolites thus acquired by ionic gelation method. Synthesized nanocomposite was found to have high stability, uniformly dispersed particles with high loading and entrapment efficiency. Insecticidal activity was studied by determination of cumulative mortality against larval instars of Spodoptera litura and changes in biochemical composition of midgut, hemolymph macromolecules which revealed that the nanocomposite was effective against all the larval stages in terms of high mortality, drastic reduction of midgut and hemolymph macromolecules biochemical composition. Biocompatibility of nanocomposite was carried out by evaluation of developmental toxicity against zebrafish and in vitro hemolysis with peripheral blood cells. Chitosan nanocomposite treatment was not induced any toxic effect on the developmental stages of zebra fish. Hemolysis was also not recorded in the nanocomposite treatment. The observed results imply that insecticidal metabolites fabricated chitosan nanocomposite prepared in our present system is a promising candidates for pest control against economically important insect pests without affecting non-target organisms.