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.