Efficacy of Eucalyptus camaldulensis leaf extracts against the pea beetle Callosobruchus maculatus and their impact on biochemical and microbiological properties of the treated bambara groundnut grains

Abstract

The present study was aimed to evaluate the efficacy of Eucalyptus camaldulensis leaf hexane, acetone and methanol extracts against Callosobruchus maculatus and their impact on biochemical, sensorial and microbiological properties of the treated Vigna subterranea grains in the laboratory. Each plant extract was applied at doses of 5, 10, 15 and 20g/kg on the bambara groundnut grains and pea beetles were released in each concentration test and C. maculatus was monitored 1, 3 and 6 days post-exposure. Effects of the plant products on progeny production F1 and damages caused by C. maculatus after three months post-storage were evaluated. Biochemical, sensorial and microbiological characteristics of the preserved seeds were also assessed. Plant extracts tested caused a significant mortality and reduced progeny production F1 of C. maculatus. Hexane extract (5g/kg) was most effective causing 78.75% mortality of insect, completely inhibited progeny production F1 and protected seeds for 3 months from insect attack. Kodek bambara groundnut variety was rich in proteins (21.53%), carbohydrates (61.24%) and minerals (3.54%). Antinutrients in treated grains increased but remained below the threshold values. The preservation of bambara groundnut grains with the plant extracts improved the organoleptic properties but affected the taste, tender and the crisp of the derived products. The plant extracts also protected V. subterranea flour against the micro-organisms.