Some aspects concerning citronella grass essential oil and the agroecological approach to protecting stored cowpea beans

Abstract

This study aimed to determine the impact of hydrodistillation duration on the chemical composition of citronella-grass essential oil. Furthermore, the oil's efficacy against cowpea weevil was evaluated by carrying out biological activity tests. The essential oil was obtained and chemically characterized. Subsequently, it was tested at different concentrations to evaluate its impact on the reproductive cycle and the total activity of the insects' biotransformation enzymes. Oxygenated monoterpene comprised the majority of the substances present. The mathematical model fitted to the extraction kinetics predicts that after 60 minutes of hydrodistillation, approximately 96% of essential oil, 94% of monoterpenes, and 50% of sesquiterpenes will be obtained with confidence. The fumigating effect of the citronella-grass essential oil resulted in increased mortality, reduced oviposition, and lower emergence of adults. The essential oil at sublethal concentration (0.09 mg cm^-3 for 6 hours) significantly reduced the total activity of biotransformation enzymes (acetylcholinesterase, α- and β-esterase, carboxylesterase) in female cowpea weevils.