Aloe ferox as a Candidate Botanical Insecticide for Stored-Grain Protection: Evidence, Knowledge Gaps, and Prospects for Sitophilus zeamais Management

Botanical insecticides are increasingly being investigated as alternatives to synthetic pesticides for stored-grain protection. This review critically evaluates Aloe ferox Mill. as a candidate botanical insecticide with potential relevance to Sitophilus zeamais Motsch, the major stored-maize pest. The available evidence related to the phytochemistry, reported pesticidal activities, proposed mechanisms of action, safety, and research needs was synthesised. A. ferox possesses a variety of secondary metabolites like anthraquinones, flavonoids, phenolics, chromones, tannins, alkaloids, and saponins, some of which have been reported to possess insecticidal, repellent, antifeedant, or growth-regulatory activity in other biological systems. But there is currently no direct experimental proof of the effectiveness of A. ferox against S. zeamais. A large proportion of the evidence relevant to pesticides is from other Aloe species, other insect and arthropod pests, or from one component or phytochemical studied in a different biological system. The findings, therefore, offer a justification for further investigations, but do not provide evidence of efficacy. Future research should focus on bioassays that directly test dose–responses, phytochemical standardisation, mechanism validation, formulation development, grain quality and residue evaluation, safety evaluation, and validation using realistic storage conditions.