Postharvest insect infestations continue to undermine global food security, especially in low- and middle-income countries. Phosphine fumigation remains the backbone of stored-product pest management; however, resistance development in key pest species such as Tribolium castaneum and Sitophilus oryzae threatens its long-term efficacy. Meanwhile, plant-derived essential oils (EOs) have garnered attention as environmentally safe alternatives due to their natural fumigant and insecticidal properties. Environmentally safe concentration thresholds of EOs typically span 50–500 ppm, varying with botanical origin, application method, and pest susceptibility, and are generally recognized as safe (GRAS) for grain consumers due to their rapid volatilization and negligible residue levels. This review synthesizes current knowledge on the combined use of phosphine and essential oils, examining their synergistic, additive, or antagonistic interactions. We explore underlying biochemical mechanisms, methodological variabilities in bioassays, and the implications of combining natural and synthetic fumigants. Methodological variabilities in insecticidal bioassays—such as differences in exposure duration (short-term vs. extended), fumigant delivery techniques (e.g., sealed chambers vs. dynamic flow systems), and test organisms (larval vs. adult stages)—present challenges in standardizing efficacy outcomes and interpreting EO-phosphine interactions reliably. Moreover, we investigate the integration of EOs in active packaging systems, their effect on shelf life and sensory qualities of stored grains, and their regulatory and toxicological profiles. By linking entomological control with food preservation and safety, this review positions EO-phosphine combinations as a promising direction in sustainable postharvest management. Key research gaps and future application strategies for integrated pest management (IPM) systems are discussed.
Hashem et al. (Wed,) studied this question.