Chitosan-Modified Diatomaceous Earth Beads for Thyme Essential Oil Delivery against Sitophilus oryzae : A New Eco-Sustainable Biocontrol Agent

High Resolution Image Download MS PowerPoint Slide The rice weevil Sitophilus oryzae L. is an ubiquitous pest of significant economic concern, representing a major threat to stored cereal grains. Essential oils (EOs) have gained attention as an eco-friendly alternative to chemical insecticides that often induce environmental and health disorders. This work aims to describe the encapsulation process of chitosan-modified diatomite loaded with thyme EO beads (CH-DE/EO). For the first time, the fumigant bioactivity of this material was evaluated as a protectant for cereal grain against S. oryzae in vivo over a 30-day storage period. Results showed that the EO was a carvacrol chemotype (78.35%). The formulated CH-DE/EO beads exhibited a specific surface area and pore volume of 165.598 m 2 /g and 0.475 cm 3 /g, respectively. Insects exposed to the LC 50 of CH-DE/EO (5.932 g/L air) achieved 100% mortality over 30 days of storage. The CH-DE/EO beads were effective in controlling S. oryzae, while maintaining the quality characteristics of the cereal grain.