Toxic, repellent and antifeedant effects of two aromatic plant extracts on the wheat granary weevil, Sitophilus granarius L. (Coleoptera: Curculionidae)

Abstract

Wheat granary weevil, Sitophilus granarius L. is considered primary pest of stored grains. In the present study, methanol extract of dill Anethum graveolens L. and purple basil, Ocimum basilicum L. var. purpurascens were evaluated for their toxic, repellent and antifeedant effects against wheat granary weevil. Both the aromatic plants had repellent and antifeedant effects but dill leaf extract showed more toxic effect on the mortality (22.08%) for wheat granary weevil. Comparing the extracts, the higher repellency was observed in purple basil leaf extract on wheat granary weevil (46.55%). The results also showed that dill leaf extract had the higher antifeedant effects on wheat granary weevil having total coefficient of deterrency 154.20. The methanol leaf extract was more effective than those of water solvent. Insect mortality percent, coefficient of deterrency and in most of the cases, repellency rate increased proportionally with doses. Mortality percentage increased with the progress of time considering all the concentration.