Antifeedant effect of two nano-capsuled essential oils against wheat weevil, Sitophilus granarius (L.) (Coleoptera: Curcurlionidae)

Abstract

Novel application methods such as nano-encapsulation of essential oils enhanced effectiveness andimproved the properties of natural insecticides. This study examined the effect of essential oils from Cuminumcyminum (L.) and Lavandula angustifolia (Mill.) and nanoparticles on nutritional parameters of Sitophilusgranarius (L.). Nano-capsules were prepared using the emulsion solvent evaporation technique and the polymerwas polyethersulfone. To evaluate nutritional indices alteration, wheat flour discs were prepared at 27 ± 1 ° C and65 ± 5% R. H. Each flour disc was treated with 0, 1, 5, 10, 15, and 20 ppm concentrations of each essential oil andnano-capsules. The results showed that both essential oils and nanoparticles significantly reduced relative growthrate (RGR), relative consumption rate (RCR), and efficiency of conversion of ingested food (ECI) in treated adults.Conversely, the feeding deterrence index (FDI) percent increased significantly as the concentration increased. Thelowest RGR and ECI at 20 ppm were observed in C. cyminum nanoparticles and the RGR reduced from 0.037 ± 0.003mg/mg/day in control to -0.176 ± 0.01 mg/mg/day and ECI percent reduced from 16.8 ± 0.99 to -336.31 ± 6.95. Thepure C. cyminum at 20 ppm caused the lowest RCR in comparison to L. angustifolia. The highest FDI was reachedat 86.13 ± 0.89 % when S. granarius was exposed to C. cyminum oil. Therefore, both the essential oils and nanocapsuleshad a behavioural effect and the encapsulation technique improved the post-ingestive toxicity in treatedadults.