Résumé:
This study aims to evaluate the insecticidal efficacy of plant extracts derived from Urtica dioica (nettle) and Ricinus communis (castor bean) against Tribolium confusum, a major pest of stored products. The two plants, selected for their richness in bioactive compounds (flavonoids, tannins, polyphenols), were subjected to Soxhlet extraction with satisfactory yields. Tests revealed that the U. dioica extract exhibited rapid and pronounced effectiveness, with a mortality rate reaching 100% on the first day at high concentrations (40%, 50%, and 100%), and an LD₅₀ of 36.30%. In contrast, the R. communis extract showed a more gradual action, with a mortality rate of 53.33% on the first day at a concentration of 40%. Furthermore, at a concentration of 50%, a mortality rate of 88.62% was recorded on the fourth day, followed by 100% mortality on the fifth day at the 100% dose. An LD₅₀ of 79.41% was recorded for the castor extract. The synergistic mixture of the two extracts demonstrated remarkable efficacy, with 100% mortality observed on the second day at a concentration of 40%, and respective mortalities of 98.72% and 92.22% observed from the first day at concentrations of 30% and 20%. An interesting LD₅₀ of 13.99% was recorded for the synergistic extract, indicating a clear synergistic effect between the two extracts. These promising results open up prospects for the development of natural bio-insecticides against T. confusum, although further studies are necessary to identify the active molecules, elucidate their mechanisms of action, and validate these findings under real storage conditions.
