The chemical sensing of pesticides is a high priority for a broad range of areas, including public health and environmental sustainability, since the pesticides have expanded dramatically in various agrarian operations. In this sense, the optical properties of non-conjugated polymer dots (NCPDs) can be a decisive advantage for sensing since the high sensitivity, fast response, and excellent photostability are very convenient properties. Here, we present the unique emission of NCPDs based on- β-glucan polymer, the major polysaccharide from the Usnea lichen biomass, which was explored for the sensing of the methyl parathion and dicloran pesticides due to the inner filter effect mechanism quenching. The sensing performance of the low-cost and eco-friendly NCPDs from renewable resources can shed light on the recent advances and applications of carbon-based nanomaterials involving non-traditional fluorescent emission systems, especially to monitor biologically and environmentally important analytes. Fluorescence sensing, Inner filter effect, Pesticides, Non-conjugated polymer dots, β-Glucan