A study on insecticidal activity of the fennel (Foeniculum vulgare) essential oil and its nanoemulsion against stored product pests and molecular docking evaluation

Abstract

The granary weevil (Sitophilus granarius) the red flour beetle (Tribolium castaneum), the sawtoothed grain beetle (Oryzaephilus surinamensis) are major pests for stored products worldwide. The development of resistance to chemical pesticides and increasing concerns about human and environmental health require the investigation of alternative control approaches. Therefore, this study focuses on formulating and characterization of the fennel (Foeniculum vulgare) essential oil nanoemulsion (FEO-N) and investigate its insecticidal properties against these pests. The major chemical components of the FEO were found as estragole (54.1 %), limonene (10.89 %), p-anisaldehyde (9.04 %) using GC-MS. The FEO-N (4:3:3:90 w/w FEO: Tween 80: Ethanol: water) was formed using an ultrasonic homogenizer and characterized with TEM (spherical shape, ∼100 nm), zeta sizer (the mean droplet particle size of 107.3±1.677 nm, the ζ-potential value of −21.7±0.755 mV), as well as FT-IR analysis. Five hundred ppm of the FEO-N caused 23.33 %, 63.33 % and 20 % mortality in T. castaneum, O. surinamensis and S. granarius after 7 days, respectively. One thousand ppm of the FEO-N caused 76.67 %, 100 % and 63.33 % mortality in T. castaneum, O. surinamensis and S. granarius after 7 days, respectively. Overall, these results clearly showed the potential insecticidal activity of the FEO-N against pests. Afterwards, the interactions of the molecules found in the FEO against Tribolium castaneum (PDB ID: 6V3T and 7LT2) were examined and benzenemethanol, 4-methoxy-.alpha.-(2-nitrocyclopentyl) molecule appears to have the highest activity against 6V3T and 7LT2 proteins. The drug properties of the molecules showing the best activity of the molecules found in the FEO were examined by ADME/T analysis.