A novel montmorillonite clay based bio-nanocomposite as an emerging biocontrol agent against stored grain pulse beetle

Abstract

Chemical pesticides have been conventionally used to control the stored grain pest infestation, but these are hazardous to humans and the environment. Therefore, the herbal pesticides are gaining more importance in insect pest management. The montmorillonite (MMT) nanoclay, is found to be an effective and underexplored adsorbent for fumigant formulation against stored grain pests. Additionally, essential oils (EOs) and their derivatives offer promising alternatives to conventional insecticides, but their application is constrained by higher volatilization, rapid decomposition, and less persistency. To address the issue, this study focuses on purifying microporous MMT through the sedimentation method and encapsulating cinnamaldehyde from cinnamon essential oil to produce a bio-nanocomposite (CEB) for management of insect pest infestations. Furthermore, the raw MMT, purified MMT, and CEB were characterized by different physiochemical techniques such as X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR). The SEM-EDX analyses demonstrated shiny irregular sheets and confirmed the presence of C-atom along with Si, O, Al, and Mg. The average crystallite size for CEB is specified to be 9.69 nm. The persistency of the cinnamaldehyde and its effective release from the CEB was confirmed by FT-IR analysis until 30 days. CEB displayed potent fumigant toxicity (LC50 = 0.37 mg/cm3) and high repellency (93.33 %) against Callosobruchus chinensis. Quantitative analysis recorded elevated protein levels (5.47 mg/ml) in treated insects. Similarly, the qualitative analysis revealed up and down-regulation of six and eight protein bands, respectively. Overall, findings show that the formulated bio-nanocomposite can better manage pulse beetle infestations in stored grains.