Insecticidal Activity of Free and Microencapsulated Cinnamomum cassia Essential Oil Against Sitophilus zeamais in Stored Maize

Control of the M LE: Please check if the authors' affiliations are presented/captured appropriately. aize weevil (Sitophilus zeamais) often relies on synthetic insecticides, which, although effective, can leave toxic residues in grains and promote the development of resistant insect populations. Certain essential oils (EOs), including Cinnamomum cassia EO, present a natural alternative recognized for their insecticidal and repellent properties. However, their effectiveness is constrained by high volatility and limited solubility. To address these limitations, controlled release technologies, such as microencapsulation, offer a promising solution. This study aimed to evaluate the chemical composition, insecticidal, and repellent efficacy of free and microencapsulated C. cassia EO against S. zeamais and the persistence and reuse potential of the microencapsulated EO in maize grains. GC–MS analysis identified trans-cinnamaldehyde (86.4%) as the major compound, followed by methyl cinnamate (9.92%). The EO was microencapsulated via spray drying with a 10% gum arabic-maltodextrin solution. Insecticidal activity showed LD₅₀ values of 8.90 μL/cm³ for free EO and 24.76 mg/cm³ for microencapsulated EO. The persistence of insecticidal activity reached 45% on the 15th day and remained nearly stable for 65 days. Moreover, the microcapsules showed effectiveness across five cycles, maintaining 70% mortality. This study highlights C. cassia EO as a sustainable solution for maize weevil management, with prolonged efficacy achieved through microencapsulation.