In silico and in vitro study of insecticidal effect of oil extracted from hemp seeds against Tribolium castaneum (Herbst)

Abstract

The protection of stored products in Morocco still relies heavily on synthetic insecticides, posing risks to human health and the environment and contributing to the emergence of resistance to these chemicals. This study explored the insecticidal potential of vegetable oils extracted from the seeds of three Cannabis sativa L. varieties (Beldia (Bld), Kherdala (Krd) and Critical (Crt) against Tribolium castaneum (Herbst) , a major pest of stored grains. The chemical composition of the oils was characterised using FTIR and GC-MS, revealing a predominance of fatty acids, particularly linoleic acid (38.97-50.11 %) and oleic acid (10.82–27.26 %). Biological tests showed significant insecticidal activity by contact, with cumulative mortality dependent on dose and exposure time. The Krd variety exhibited the highest toxicity (LD50 = 3.75 mL kg-1), followed by Bld (5.61 mL kg-1) and Crt (7.39 mL kg-1). Furthermore, oils from the Bld and Crt varieties demonstrated strong repellent properties, reaching 91.67 % and 68 %, respectively, at 0.63 µL/cm², while Krd showed weak repellency. Molecular docking analyses suggest that certain major fatty acids, particularly linoleic and oleic acids, interact strongly with acetylcholinesterase, a classic target enzyme for insecticides, reinforcing the hypothesis of their active role in the observed insecticidal effects. These results highlight the potential of C. sativa seed oils as effective and safe bioinsecticides, offering a sustainable alternative to chemical insecticides for the post-harvest protection of cereals in Morocco.