ASSESSMENT OF DIFFERENT NEEM PRODUCTS FOR THE MANAGEMENT OF RICE WEEVIL (SITOPHILUS ORYZAE L.) IN STORED RICE GRAIN

Abstract

The experiment was conducted to study the damage assessment and effect of different neem products for the management of rice weevil (Sitophilus oryzae L.) in stored rice grain during the period from July to December 2013. Stored husked and unhusked rice of BR 27 were used as the experimental materials. The experiment consists of the treatments: T1: Neem leaves dust 10 gm/kg of stored rice grains; T2: Neem seed kernel dusts @ 10 gm/kg of stored rice grains; T3: Neem leaves extract @ 10 ml/kg of stored rice grains; T4: Neem oil 5 ml/kg of stored rice grains and T5: Untreated control. The experiment was laid out in the ambient condition of the laboratory following in a Completely Randomized Design (CRD) and the treatments was replicated four times for each. In case of unhusked rice, the highest mortality (100.00%) was observed in T4 treatment, while the lowest 5.25% mortality was recorded in T5 treatment. For husked rice, the highest mortality (100.00%) was observed in T4, while the lowest mortality (9.00%) was recorded in T5 treatment. At 1st generation for unhusked rice, in weight basis, the highest infestation was recorded from T5 (9.49%) treatment while the lowest in T4 (1.32) and for husked rice, the highest infestation was recorded from T5 (10.68%), while the lowest in T4 (2.79%) treatment. On the other hand, by number basis in unhusked rice, the highest infestation was found from T5 (11.57%), while the lowest in T4 (2.47%) treatment and for husked rice, the highest infestation was found from T5 (14.72%) while the lowest in T4 (3.86%) treatment. Similar trend of results were revealed from the 2nd and 3rd generations. At 1st generation, for unhusked rice, the highest weight loss was found in T5 (18.21%), while the lowest was found in T4 (3.89%) treatment and for husked rice grain, the highest weight loss was recorded in T5 (21.45%), whereas the lowest was observed in T4 (4.38%) treatment. Similar trend of result also recorded in 2nd and 3rd generation. In case of repellency effect for unhusked rice, after 5 hours of treatment application the highest repellency rate was found from T4 and T3 (100.00%), whereas the lowest repellency rate (80.00%) was recorded in T1 treatment. In case of repellency effect for husked rice, after 5 hours of treatment application the highest repellency rate was found from T4 and T3 (100.00%) treatments which was followed by T1 and T2 (90.00%) treatments. Among the neem products neem oil 5 ml/kg of stored rice grains was more effective for controlling rice weevil.