Control of Rice weevil,Sitophilus oryzae (L.)

Effect of Diflubenzuron and Diflubenzuron in Combination with Neem Oil on the Life Stages and Developmental Periods of Rice Weevil, Sitophilus oryzae (L.)

Abstract

Effect of diflubenzuron (DFB) and diflubenzuron in combination with neem oil (NO) on the life stages and developmental periods of rice weevil, Sitophilus oryzae (L.) was studied. The fresh polished rice and egg, larva and pupa infested rice were treated with DFB and DFB-NO at four different doses viz. 2-, 4-, 8- and 16 mg/kg and 2+2.25-, 4+2.25-, 8+2.25- and 16 mg/kg+2.25ml/kg, respectively.

The adult emergence was significantly (P<0.001) reduced in both DFB and DFB-NO treatments on grain and life stages (egg, larva and pupa) of S. oryzae. The lowest number of adult emergence from treated grains, eggs, larvae and pupae were 3.00±1.00 and 2.00±0.00, 3.33±0.33 and 2.00±0.58, 11.00±1.00 and 6.33±0.88, 10.67±0.88 and 5.33±0.33 respectively at 16 mg/kg and 16 mg+2.25 ml/kg of DFB and DFB-NO treatments in comparison to control (16.33±1.45, 28.00±0.58, 75.67±1.85 and 40.00±3.46 respectively) whereas the highest number of adult emergence from treated grains, eggs, larvae and pupae were 5.00±0.58 and 3.33±0.88, 15.67±0.88 and 6.33±1.33, 74.00±1.73 and 11.67±2.90, 39.67±1.45 and 20.67±0.33 respectively at 2 mg/kg and 2 mg+2.25 ml/kg of DFB and DFB-NO treatments in comparison to control (16.33±1.45, 28.00±0.58, 75.67±1.85 and 40.00±3.46 respectively).

The highest number of inhibition rate from treated grains, eggs, larvae and pupae were 81.64 and 87.76%, 88.09 and 92.86%, 85.46 and 91.63%, 73.34 and 86.66% at 16 mg/kg and 16 mg+2.25 ml/kg of DFB and DFB-NO treatments respectively whereas the lowest number of inhibition rate from treated grains, eggs, larvae and pupae were 69.38 and 79.60%, 44.04 and 77.38%, 2.20 and 84.91%, 0.83 and 48.34% at 2 mg/kg and 2 mg+2.25 ml/kg of DFB and DFB-NO treatments respectively.

The highest numbers of deformed adults were emerged from treated pupae recorded as 4 and 12 of all doses of DFB and DFB-NO treatments respectively whereas the lowest numbers were emerged from treated grain was 1 at 16 mg+2.25 ml/kg.

The highest number (24.67±2.40 and 35.67±0.33; 16.67±2.84 and 28.33±1.67) of adults were failed to emerge significantly (P<0.001) from treated larvae and pupae with DFB and DFB-NO treatments respectively at 16 mg/kg and 16mg+2.25 ml/kg doses whereas lowest was found for 2mg/kg and 2mg+2.25 ml/kg doses.

Finally it can be concluded that DFB and DFN-NO can be used as potential agent against stored product insects therefore detailed study is needed on these compounds in large extent.

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