Efficacy of three indigenous plant oils against rice weevil, Sitophilus oryzae Linn., on stored wheat

Rice weevil (Sitophilus oryzae Linn.) (Coleoptera: Curculionidae) causes heavy loss to the wheat (Triticum aestivum Linn.) during storage. Traditionally in Punjab rural villages, neem products are being commonly used for storage of cereal grains. Current investigations were carried out by using oils from neem, eucalyptus and castor; each @ 0.10, 0.15 and 0.20 per cent (v/w) against S. oryzae by directly mixing with the wheat grains. Neem oil at 0.20 per cent was found highly effective due to minimum grain damage (2.86%), weight loss (1.39%), adult emergence (22.83 adults/100g grain sample) and maximum inhibition rate (91.06%). Eucalyptus oil ranked second based on minimum grain damage (3.83%), weight loss (1.78%) and adult emergence (31.8 adults/100g grain sample) followed by castor oil. No significant differences were noticed for seed viability and moisture content in treated and untreated samples for up to 120 days after treatment.