Biological Preparation, Characterization of CaO Nanoparticles from Egg Shell Waste and Insecticidal Activity against Seed Weevil, Sitophilus oryzae L. in Maize

Calcium oxide (CaO) nanoparticles was biologically synthesized by calcinating egg shells from kitchen waste and characterized using SEM, UV-Vis, XRD and FT-IR. Biosynthesized CaO nanoparticles are found to be an effective insecticide against seed weevil, Sitophilus oryzae in maize. The indiscriminate use of already available commercial pesticides has led to develop resistance among the pests and also occurrence of pesticide residues in produce. The SEM study revealed that the particles are granular in shape with a size of 189 nm. The diffraction peaks of XRD were observed at 2θ = 32.320, 37.48°, 48.40°, 53.96°, 64.18°, 67.52°and exhibited polycrystalline nature. In the FTIR spectrum, a broad band at 1410 cm-1, a sign of a C-O bond which indicated the association between the oxygen atom of carbonate and the calcium atom. The insecticidal activity of CaO nanoparticles was assessed against S. oryzae by contact toxicity bioassay method. The outcomes of the bioassay studies showed that the lethal dose (LD50) for maize seeds was 72.62 mg/100 g. and within seven days of exposure, 100% death of S. oryzae was attained at a dosage of 240 mg/100 gm of maize seeds. The current study concluded that biosynthesized CaO nanoparticles may be used as an effective management technique to successfully manage the S. oryzae under storage conditions as an alternative to chemical pesticides.