Characterization of silver nanoparticles synthesized by Bacillus thuringiensis as a nanobiopesticide for insect pest control

Authors: SAYED, ATEF - Plant Protection Research Institute; Kim, Sanghoon; Behle, Robert

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2017
Publication Date: 11/3/2017
Citation: Sayed, A.M., Kim, S., Behle, R.W. 2017. Characterization of silver nanoparticles synthesized by Bacillus thuringiensis as a nanobiopesticide for insect pest control. Biocontrol Science and Technology. 27(11):1308-1326. http://dx.doi.org/10.1080/09583157.2017.1397597.
DOI: https://doi.org/10.1080/09583157.2017.1397597

Interpretive Summary: Silver nanoparticles are known to have antimicrobial activities whereby these particles can be utilized for pest control. Nanoparticles are tiny particles that are so small, they are not visible even with optical microscopes. An array of physical and chemical methods has been used for the synthesis of nanoparticles, but they are less stable, expensive, and involve the use of hazardous chemicals in synthesis. Alternatively, silver nanoparticles can be produced by mechanisms of biological origin, such as microorganisms or plant extracts. These biological systems are environmentally-friendly with minimal biological and environmental risks. In this report, silver nanoparticles were synthesized by using a bacterium (named B. thuringiensi var. kurstaki) as a low-cost and eco-friendly production system, and the insecticidal performance of the produced nanoparticles was demonstrated against two types of larvae. This research addresses current concerns for the production of silver nanoparticles by a simple and environmentally-friendly system. Scientists in industry and academia developing commercially viable silver nanoparticle products would benefit.

Technical Abstract: Nanotechnology has become one of the most promising new approaches for pest control in recent years. In this research, biocompatible silver nanoparticles (Btk-AgNPs) were synthesised by using the entomopathogenic bacterium, Bacillus thuringiensis kurstaki (Btk) as a low-cost and eco-friendly production system. The AgNP samples exhibited a brownish-yellow colour that is characteristic for silver nanoparticles synthesis. Btk-synthesised AgNPs were produced using both the supernatant and pellet of Bt culture at various concentrations and AgNP particles were characterised by UV-Vis spectrophotometer and Dynamic Light Scattering (DLS). The variation of hydrodynamic diameter (Dh) and UV-Vis spectra of silver particles produced by various concentration of culture showed that production of AgNPs was maximised when using 20% for either supernatant or pellet treatments of Bt of culture and the size of particles was around 85 nm for both. The insecticidal efficacy of Btk-synthesised AgNPs against larvae of the cabbage looper, Trichoplusia ni (Hübner) and black cutworm, Agrotis ipsilon (Hufnagel) was tested. Results demonstrated that the treatments of either Btk-synthesised AgNP(s) made with Bt supernatant or Btk-synthesised AgNP(p) using Bt pellet were found to be significantly more virulent toward larvae of T. ni than to A. ipsilon.