Encapsulated Bio-insecticide from Citrus aurantium (Rutaceae) Essential Oil and Pectin and Potential for the Control of the Lesser Grain Borer Rhyzopertha dominica (Bostrichidae)

Background Citrus aurantium essential oil was extracted from fruits collected from two regions namely Nabeul and Boussalem, characterized by diverse climatic and geographic conditions. Essential oils were investigated for their yield, chemical components, antioxidant and insecticidal activities against adults of the lesser grain borer Rhyzopertha dominica . Then, the essential oil that has the highest insecticidal activity was encapsulated into pectin:Gum Arabic and tested by fumigation against R. dominica adults. Additionally, emergence inhibition of their offspring was assessed. Methods Pectin and essential oils were extracted from C. aurantium fruit peels by acid extraction chemical method and hydrodistillation, respectively. GC–MS analysis was used to identify the chemical components of the essential oils. Microcapsules were prepared at different ratios with various concentrations of pectin–Gum Arabic matrix. The encapsulation efficiency (EE %), loading capacity (LC %) and cumulative release (CR %) were determined using UV–Vis spectrophotometer. Crude and encapsulated Citrus aurantium essential oil in pectin–Gum Arabic-based microcapsules was tested by fumigation against adults of the lesser grain borer Rhyzopertha dominica for three storage durations (30, 60 and 90 days). Phosphine was used as conventional fumigant insecticide. Results Results showed that microcapsules with pectin–Gum Arabic:Eo (0.5:2.5:1) was characterized by the highest EE (81.062%) and LC (5.79%). Fumigation tests revealed that encapsulated essential oil exhibited an effective control against R. dominica adults and their descendants during the three storage periods with 100% of mortality and emergence inhibition, compared to crude essential oil which generates 100, 90 and 60% of emergence inhibition, respectively after 30, 60 and 90 days of storage. Conclusion Wastes from Citrus aurantium produce valuable products as pectin and rich limonene essential oils. Microcapsules based on pectin:Gum Arabic:essential oil could be utilized as an effective bio-insecticide for the control of insect pests in storage commodities.