Study On Environmental Behavior,Biological Activity And Toxicity Of Broflanilide In Paddy Field

Broflanilide is a m-benzamide benzamide with novel mechanism of action,strong insecticidal activity and no cross-resistance with traditional insecticides,jointly developed by Japan’s Mitsui Agricultural Chemicals and BASF Europe.Insecticides,there is still a lack of in-depth and systematic research on their environmental behavior,biological activity and toxicity effects in rice fields.In this paper,starting with the analysis method of Broflanilide residues,an efficient,simple and quick method for the extraction and detection of Broflanilide residues in the paddy field environment was developed,and the method was used to analyze the Broflanilide residues.Adsorption,leaching and migration behavior of Broflanilide in soil,soil degradation,hydrolysis and photolysis behavior in rice environment,and digestion dynamics on rice;through laboratory toxicity determination and field experiment,explored Broflanilide Biological activity of bisamide to several main pests on rice;systematically tested the toxicity of Broflanilide on non-target organisms such as spiders,Italian bees,zebrafish,three-leaf duckweed and earthworms.It is bromine The safety assessment,ecological risk assessment and popularization and application of Broflanilide in rice production provide a theoretical basis and scientific basis.（1）In this paper,a Qu ECh ERS-HPLC method for the determination of Broflanilide residues in rice environmental-related samples is established.The recovery rate is93.59%～99.25%,and the relative standard deviation（RSD）is 2.29%～7.05%.The detection limit（LOD）of this method is 0.16～1.67μg/kg,and the limit of quantification（LOQ）is 0.54～5.48μg/kg.The optimal chromatographic conditions for the purification of Broflanilide residues in rice environmental-related samples by Qu ECh ERS program are:the mobile phase is a 75:25 volume ratio of acetonitrile-water system containing0.1%formic acid;the detection wavelength is 254 nm;the column temperature is 40°C;flow rate 0.5 m L/min;sample volume is 10μL;the best conditions for the extraction of rice environment-related samples are:50 mg PSA+150 mg Mg SO₄for paddy water,50mg C18+150 mg Mg SO₄for paddy soil And rice,50 mg C18+10 mg GCB+150 mg Mg SO₄is used for rice plants and rice husks.The matrix effect of Broflanilide in rice samples is-69%～-54%,which has a signal inhibitory effect.Digestion dynamic tests showed that the half-lives of Broflanilide in paddy soil,paddy water and rice plants were0.67 to 2.67 d,2.30 to 5.55 d and 1.52 to 3.53 d,respectively.14 days after application,the digestion rate of Broflanilide in rice and related environmental media exceeded 90%.When the rice was harvested,the final residues of Broflanilide in the rice were all below the limit of quantification.Therefore,Broflanilide is a kind of easily degradable pesticide,and it could be safely used in rice production at the recommended dosage.（2）The results of the adsorption and desorption test showed that the adsorption capacity of four different soils for Broflanilide was as follows:Luvisols（Hebei cinnamon soil）<Gleysols（Sichuan purple soil）<Anthrosols（Zhejiang paddy soil）<<Phaeozems（Heilongjiang black soil）.Except for the Phaeozems（Heilongjiang black soil）soil,the adsorption capacity of other test soils for Broflanilide is generally low.The Freundlich adsorption constant(K_F-ads)of the four test soils for Broflanilide is between 0.152 and5.017.The soil organic matter content and clay content are related to the Freundlich adsorption constant(K_F-ads)and desorption constant(K_F-des).Is linearly positively correlated（R²=0.893,0.851,R²=0.765,0.686）,and the adsorption capacity and desorption capacity of soil for Broflanilide are negatively correlated with soil p H to a certain extent（R²=0.095,0.089）,And the relationship with the cation exchange capacity is not significant（R²=0.428,0.384）.In the four kinds of soils,theΔG value is lower than 0 under different temperature conditions,so the adsorption process of the four kinds of soils to Broflanilide is spontaneous and belongs to physical adsorption.The adsorption capacity of soil to Broflanilide will decrease at temperatures higher or lower than 287 K.Among the four tested soils,only Luvisols（Hebei cinnamon soil）has a higher adsorption rate for Broflanilide than its desorption rate,and the adsorption and desorption rates of the other three soils for Broflanilide are close to equilibrium.state.The results of the leaching migration simulation test showed that the organic matter content and clay content in different soils are the main factors affecting the leaching behavior of Broflanilide.The leaching and migration ability of Broflanilide in four different soils is as follows:Luvisols（Hebei cinnamon soil）>Gleysols（Sichuan purple soil）>Anthrosols（Zhejiang paddy soil）>>Phaeozems（Heilongjiang black soil）,with respect to bromine The stronger the adsorption capacity of Broflanilide,the weaker the leaching and migration capacity of soil.The results showed that,except for the Phaeozems（Heilongjiang black soil）soil,the groundwater and surface water in the other three tested soil environments may be contaminated by the leaching and migration of Broflanilide,and there is a certain ecological risk.（3）In the hydrolysis test,the shortest half-life of Broflanilide in water is 39.6 h（p H9,45℃）,and the hydrolysis rate is positively correlated with the culture temperature,that is,the higher the culture temperature,the hydrolysis rate of Broflanilide The faster;the hydrolysis rate is also positively correlated with the p H value of the buffer solution.The higher the p H value of the buffer solution,the faster the hydrolysis rate of Broflanilide,because of the hydrolysis rate of Broflanilide in alkaline aqueous solution It is much greater than the rate of hydrolysis in acidic and neutral aqueous solutions,so the hydrolysis of Broflanilide is alkaline hydrolysis.In the soil degradation test,the shortest half-life of Broflanilide in soil is 59.2 h（unpasteurized soil,35℃）,and the degradation rate in unsterilized soil is much higher than that in sterilized soil,which confirms that the soil Microorganisms play a vital role in the degradation of Broflanilide in the soil;the soil degradation rate of Broflanilide is positively correlated with the cultivation temperature.As the cultivation temperature increases from 15℃to 35℃,The degradation rate of Broflanilide in soil has been accelerated,the half-life in unsterilized soil is shortened from 124.8 h to 59.2 h,and the half-life in unpasteurized soil is shortened from 6011.3 h to 254.7 h.In the photolysis test,in the p H range of 4～9,with the increase of the p H value of the solution,the photolysis rate of Broflanilide also increased,and the half-life was shortened from 25.3 min to 11.2 min;the photolysis rate was similar to that The initial concentration of Broflanilide is negatively correlated,the higher the initial concentration,the slower the photolysis rate.In addition,the degradation test results are consistent with the digestion dynamic results.Under summer temperature conditions（>30℃）,the degradation half-life of Broflanilide in paddy water is less than 5.55 d（133.2 h）.Paddy soil（natural conditions,non-sterilized）The degradation half-life of Broflanilide in)is less than 2.67 d（64.08 h）.（4）The laboratory virulence test results showed that the LD₅₀for Chilo suppressalis and Cnaphalocrocis medinalis were 0.0096μg/g and 0.0093μg/g,respectively,and the LD₅₀for Nilaparvata lugens Stal>115.3729μg/g,which shows that Broflanilide has extremely high biological activity against Chilo suppressalis and rice leaf roller,but has low biological activity against Nilaparvata lugens Stal.With Flubendiamide as the standard agent,the relative virulence indexes of Broflanilide against Chilo suppressalis and Cnaphalocrocis medinalis were 1.56 and 1.7,respectively.The toxic activity of Broflanilide and the control agent Emamectin benzoate on rice thrips is stronger,and the Broflanilide is slightly weaker than Emamectin benzoate.The LC₅₀of the two agents is0.23 respectively at 48 h after the treatment.mg/L and 0.20 mg/L.During the 48-hour action time,with the increase of the dosage and action time,the insecticidal effect of Broflanilide and Emamectin benzoate on rice thrips is better.At the concentration of 10mg/L,the mortality of thrips could reach 98.25%.The field control effect test results showed that Broflanilide and the control agent Flubendiamide have better field efficacy against Chilo suppressalis and Cnaphalocrocis medinalis.With the increase of the dosage,the insecticidal effect will increase.The heart rate is reduced,the effect of both the seedling preservation and leaf preservation is improved.Broflanilide and the control agent Flubendiamide have no obvious field control effect on Nilaparvata lugens Stal.（5）In this study,the toxicity test of Broflanilide on five non-target organisms in the rice ecological environment system was carried out.The results show that Broflanilide has a certain effect on the growth and decline of spiders on rice.In the treatment with the dosage of 18.75～30.00 g/hm²,the reduction rate of spider insect population in 2018 and2019 after 3 days is 27.88%～38.12%,24.77%～34.10%,respectively.The results of the digestion dynamic test showed that the T_1/2of Broflanilide on rice plants was less than 4d,that is,its digestion in rice was faster,and the spider density of all treatments returned to the pre-dose level 7 days after the treatment.Broflanilide is not toxic to Italian bees.As the concentration increased from 0.1 mg/L to 120 mg/L,the action time was extended from 48 h to 96 h.No abnormal behavior or death occurred in all treatments of Italian bees.However,the control agent Flubendiamide showed certain toxicity to Italian bees.As the concentration increased from 0.1 mg/L to 20 mg/L,the mortality of Italian bees increased from 1.67%to 63%.Broflanilide is toxic to zebrafish.In low-concentration treatment,zebrafish will have symptoms of gill hyperemia,whitish skin and slow movement.The toxic effect of Broflanilide on duckweed is"low（concentration）promoting high（concentration）suppression"toxic effect,that is,when the concentration is less than 0.24 mg/L,it shows stimulating effect and promotes the growth of duckweed,And when the concentration is greater than 0.24 mg/L,the growth of duckweed can be significantly inhibited,and the inhibitory effect is significantly positively correlated with the treatment concentration and treatment time.Broflanilide is acutely toxic to Eisenia vulgaris,with LC₅₀of 89.31 mg/kg and 83.11 mg/kg at 7 d and 14 d,respectively.Some individuals died 2～7 d after administration,but after 7 d of administration There were no new dead individuals,which indicated that Eisenia vulgaris had strong adaptability or detoxification ability to Broflanilide.In summary,Broflanilide is relatively safe for the ecological environment.