Virulence Tests of Fipronil,Chlorpyrifos and Acetadpdd’s Pesticidal Complex to Rice Water Weevil and Their Field Effect

In order to find a best pesticide to control the rice water weevil in Shuangfen county of Hunan province,three pesticides were screened and their virulences test were performed in room and field.The main results showed that LC50(24h) was fipronil 4.85 mg.L-1,chlorpyrifos 34.89 mg.L-1 and acetadpdd 76.28 mg.L-1 respectively.Compared with chlorpyrifos and acetadpdd,fipronil showed a better effect on RWW.Furthermore,two of insecticides mentioned above were mixed randomly together to observe their prevention effects and the results indicated that fipronil combined with chlorpyrifos achieved an op-timal LC50(24h) of 3.29 mg.L-1.Moreover,field test results showed that a mixed solution of 5% fipronil coupled with 15% chlorpyrifos diluted by 1000 times in complex reagent treatment achieved an optimal effect,controlling efficiency was 90%.