Contribution to the Development of Burundi's Plant Heritage in the Management of Cereal Stocks: Case of Eucalyptus Maidenii Essential Oil and Citrus limon leaf powder against Insect Pests of Maize Grains

With the aim of contributing to the development of Burundi's plant heritage in the control of stored food pests, a study on the extraction and physico-chemical characterisation of the essential oil of Eucalyptus maidenii, the incorporation of this plant essence into Citrus limon leaf powder and the evaluation of the effectiveness of this mixture in the conservation of maize grains was carried out in the laboratory of Burundi University, from October 2021 to February 2022. The essential oil was extracted using locally manufactured equipment, and the physico-chemical characterisation involved determining the relative density, refractive index, acid index, peroxide index, carbonyl index and ethanol miscibility. Two types of mixtures of essential oil and Citrus limon leaf powder were then formulated with proportions of 1/20 (w/w) for the first mixture (M1) and 1/10 (w/w) for the second mixture (M2). Cleaned maize grains were distributed in 63 jars of 500 ml at a rate of 200 g per jar, then infested with 1 g of powder containing insect eggs. Each mixture was applied in 5 doses (0.05%; 0.5%; 1%; 1.5%; 2%) with 3 repetitions for each dose. The extraction process yielded 3.6% essential oil. After 4 months of storage, the average attack rate on maize grains was 1.58% in the control batches compared with 0.37% in the treated batches. On average, 7 insects appeared in the control batches compared with only 2 in the treated batches, and the insect mortality rate was 100% in almost all the treated batches.