Investigation On Occurrence Law Of Rice Water Weevil And Screening Of Novel Insecticides For Its Controlling In Shuangfeng County

Lissorhoptrus oryzophilus Kuschel is considered as a destructive quarantine pest and seriously threatens rice production. To learn occurrence law of Rice Water Weevil(RWW) in Shuangfen county of Hunan province and in turn to control it, the status quo of RWW was investigated field experiments and some pesticides were screened accordingly. The main results were shown as follows:It was found that Rice water weevil end its hibernation period in March and thereafter begin to propagate twice a year. Virulence test was carried out to study dose effects of fipronil, chlorpyrifos and acetadpdd on RWW and it was indicated that LC50(24h) was fipronil 4.85mg/L, chlorpyrifos 34.89mg/L and acetadpdd 76.28mg/L respectively. Compared withchlorpyrifos 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 results indicated that fipronil combined with chlorpyrifos achieved an optimal LC50(24h) of 3.29.Moreover, field test results showed that fipronil achieved an optimal effect in single reagent treatment and the same was true for a mixed solution of 5% fipronil coupled with 15% chlorpyrifos diluted by 1000 times in complex reagent treatment. The optimal times of spraying is 4 days after transplanting at 17: 00-18: 30, and in turn a 90% controlling efficiency can be achieved.In addition, an optimal control technique was developed by quantifying dispersant and thickener in mixed solution of 5% fipronil and 15% chlorpyrifos. Also, the technique strategy developed above was awarded with national patent, suggesting it as being feasible.