Insights into insecticidal efficacy of Cymbopogon essential oils against Callosobruchus chinensis: An integrated approach through bioassays and in-silico molecular docking for sustainable pest management

Post-harvest losses attributed to insect pests, particularly Callosobruchus chinensis, pose a significant threat to global food security. Although synthetic pesticides have proven efficacy, their environmental and health implications highlight the need for safer alternatives. This study investigates the insecticidal properties of essential oils from Cymbopogon khasianus (CKEO) and Cymbopogon flexuosus (CFEO) against C. chinensis.

The results demonstrate that CKEO and CFEO possess considerable fumigant toxicity and repellent properties against adult C. chinensis. Notably, CFEO exhibited enhanced toxicity across all concentrations tested, with LC₅₀ values ranging from 86.81 μL/L to 27.50 μL/L over 96 h, whereas CKEO showed LC₅₀ values of 187.86 μL/L to 52.97 μL/L. In repellent assays, CKEO was notably effective at lower concentrations (16.13 μL/L), achieving 33.33 % repellency at 13.13 μL/L, while CFEO outperformed CKEO at higher concentrations (48.39 μL/L), reaching 93.33 % repellency after 6 h of exposure.

Among the key phytochemicals identified through GC-MS, trans-Methylisoeugenol (43.16 %) and Citral (34.56 %) were the predominant compounds in CKEO and CFEO respectively. Additionally, both oils contained other significant monoterpenes and sesquiterpenes, recognized for their substantial contact toxicity and repellent properties.

Molecular docking studies indicate that Caryophyellene oxide has a strong inhibitory potential against insect α-amylase, with a binding affinity of -7.62 kcal/mol. Furthermore, p-Camphorene shows notable binding affinities of -9.08 kcal/mol for odorant receptors, and -7.30 kcal/mol for NADH oxidoreductase, indicating its potential functional significance in biochemical interaction.

These findings highlight Cymbopogon essential oils as effective and sustainable pest management alternatives. Integrating bioassay techniques with molecular docking, reveals the mechanisms behind their effectiveness, providing important insights vital for sustainable pest management strategies.