Pathak, MaheshKalita, Hia2023-02-242023-02-242022-10https://krishikosh.egranth.ac.in/handle/1/5810194456Sericulture is the rearing of silkworms for the production of raw silk. Silk “the textile Queen” is secreted by the silkworms. Silkworm is an economically important holometabolous insect belonging to the order Lepidoptera. Over the past 50 years, the use of synthetic pesticides for crop protection has rapidly expanded around the world. The need for innovative low-risk control methods and new chemical classes of pesticides has increased as a result of the increasing concern for the environment and human health. In order to protect future agriculture and the environment in India, the post-Green Revolution era calls for a reduction in the use of more fertilizers and pesticides. Recently, nanotechnology being embraces in the world of pest control has the potential to revolutionize modern day agriculture. The rapid development of nanomaterials in various fields of science results in the need of understanding their toxicity on development and physiology of non-target organisms. In the present study, three nanoparticles (NPs) Chitosan, Silver (Ag) and Zinc oxide (ZnO) at seven different concentrations (25, 50, 100, 200, 300, 400, 500 ppm) were used to study their effects on the morphology and histology of Eri silkworm (Samia Cynthia ricini, Boisduval). The nanoparticles were incorporated in their diet by leaf dip method and applied once in each instar. In the larval and pupal stages the length, girth and cocoon weight decreased with increased concentrations of the nanoparticles. At 500 ppm length of larvae treated with Chitosan, Ag and ZnO NPs were 3.99, 4.37 and 5.98 cm as compared to control (7.12 cm), girth of larvae treated with Chitosan, Ag and ZnO NPs were 1.67, 3.31 and 4.49 cm as compared to control (4.78 cm) and cocoon weight of pupae treated with Chitosan, Ag, ZnO NPs were 1.94, 2.03 and 2.83 g/cocoon as compared to control (2.833 g/cocoon). The corrected larval mortality increased with increased concentrations, highest at 500 ppm with 22.18%, 17.73% and 12.18% in Chitosan, Ag and ZnO NPs, respectively. At 500 ppm deformities like absence of silken cocoon in the pupae, failed adult emergence, pupal death and deformed wings in the adults were observed in the morphology of the silkworms. At 500 ppm NPs decreased the fibroin protein content in the cocoons of Chitosan (68.03%), Ag (71.13%) and ZnO (69.49%) as compared to control (77.92%). Defects like split end, slug, bad casting, waste and loop in the silk threads also increased with increased concentration in all the three NPs. The midgut tissues of the dead larvae treated at 500 ppm of the NPs observed under Transmission Electron Microscope (TEM) exhibited alterations in the epithelial layer, basement membrane and muscle layer. In all the three nanoparticles absence of microvilli, empty cell contents and disruption of mitochondria was observed.EnglishThesis