Toxicity of citronella essential oil and its nanoemulsion against the sawtoothed grain beetle Oryzaephilus surinamensis (Coleoptera: Silvanidae)

Abstract

Sawtoothed grain beetles, Oryzaephilus surinamensis (Coleoptera: Silvanidae), cause severe damage to various stored products, reducing their quality and nutritional value. Several chemical pesticides have been introduced to control this pest and mitigate damage, but these pesticides also affect human health and the environment, enticing researchers to seek safer products and technology, such as plant-based products and nanotechnology. In this study, we compared the effectiveness of citronella essential oil and its nanoemulsion in controlling O. surinamensis adults. The citronella essential oil was obtained through hydrodistillation, and analyzed using gas chromatography (GC) and GC/mass spectrometry (MS based on the GC-MS analysis, the predominant compounds were citronellal (46.95%), citronellol (9.49%), linalool (9.46%), β-caryophyllene (8.39%). The particles size of the prepared nanoemulsion was 57.98 nm. The lethal concentration that causes 50% mortality (LC50) in O. surinamensis adults for the pure essential oil and its nanoemulsion was 10, 15, 20, and 25 µL/L. The nanoemulsion was more effective against both females (LC50 = 20.3 µL/L) and males (LC50 = 15.7 µL/L) than the pure essential oil (LC50 = 40.02 and 52.5 µL/L, respectively). There was a significant difference in toxicity between the pure essential oil and its nanoemulsion. In addition, there were statistically significant differences (P < 0.05) between males and females when using citronella nanoemulsion only. In conclusion, citronella nanoemulsion is effective in controlling O. surinamensis and represents a promising alternative to chemical pesticides for protecting stored products.