Citrus Limonene as a Potential Source of Biopesticides Against Maize Weevils

The maize weevil is a major postharvest pest of stored maize, causing substantial quantitative and qualitative grain losses and posing a serious threat to food security. In many regions of the world, particularly in developing countries where maize is a staple crop, maize weevil infestations can account for up to 50% of postharvest maize losses annually. Traditionally, synthetic pesticides have been used to manage maize weevils, but their prolonged application has been associated with environmental contamination, pesticide resistance, and adverse health effects in humans and animals. These challenges have inspired the search for safe, eco-friendly, and bioactive alternatives from natural sources. Citrus plants are among the most widely consumed fruits globally, with their peels and leaves constituting a significant proportion of agricultural waste. These waste products are rich in essential oils, particularly limonene, which has demonstrated potent insecticidal properties against maize weevils. Repurposing citrus waste into biopesticides offers a sustainable strategy for mitigating maize weevil infestations, thereby reducing postharvest maize losses and enhancing food safety and security. This review examines the prospects of citrus limonene in the development of safe and effective maize weevil biopesticides, highlighting its major chemical constituents, biological activities, and mechanisms of action.