Biofabrication of Microbeads Infused with Acorus calamus Oil and Eucalyptus Extract for Sustainable Stored Grain Pest Management

Postharvest infestations pose a significant threat to food grains, causing substantial losses, i.e., around 50–60%. Conventional synthetic pesticides used for their control have raised environmental concerns and public health concerns. In this study, an innovative approach to pest management was introduced by developing encapsulated, sustained-releasing bioinsecticidal microbeads containing Acorus calamus essential oil and eucalyptus leaf extract. These microbeads were meticulously designed, considering their physicochemical properties, shelf life, and release kinetics following CIPAC guidelines. To facilitate practical application, these controlled-release microbeads are packaged in perforated pouches, allowing convenient placement and removal from stored grains. Furthermore, the bioactive compounds, asarone in Acorus calamus essential oil and eucalyptol (cineole) in a eucalyptus leaf extract, were quantified by using GC-MS analysis. This study involved extensive optimization of release rates, with diffusion processes accurately modeled by the Higuchi square root model (r²). Laboratory experiments demonstrated exceptional efficacy, with a 65% mortality rate for Tribolium castaneum after 24 h of exposure, increasing to 90% after 12 days of in vitro testing. Intriguingly, exposure to the microbeads resulted in complete sterility of the T. castaneum, accompanied by a cessation of egg-laying activity. These findings highlight the potential of this novel integrated pest control system, offering a sustainable and effective means of safeguarding essential food grains during storage. This environmentally friendly approach presents a promising solution to the challenges posed by postharvest infestations.