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Thiamethoxam and beta-cyfluthrin are commonly used insecticides for aphid control in greenhouse celery. It is of great significance to reveal their dissipation and accumulation characteristics for evaluating their dietary intake risks and optimizing application methods. Based on this, gas chromatography-tandem triple quadrupole mass spectrometry was used in the multi-reaction monitoring mode of mass spectrometry, The dynamics of residue digestion of two insecticides under three repeated spraying methods (combination I: thiamethoxam + beta-cyfluthrin, alternating II: thiamethoxam -betacyfluthrin - thiamethoxam, alternating III: beta-cyfluthrin - thiamethoxam - beta-cyfluthrin) and assessed the risk of chronic dietary intake. The results showed under the three continuous spraying methods, the original deposition amount was the highest after the second spraying (22 d after planting) and the lowest after the first spraying; and the celery leaf area index may be an important factor causing this phenomenon. According to the first-order kinetic equations, the digestion half-life of thiamethoxam and beta-cyfluthrin were 2.95-3.63 d and 2.33-3.11 d, respectively. Comparative analysis of residues after the safety interval of 7 d after three repeated spraying, residue of thiamethoxam and beta-cyfluthrin in combination I was higher than maximum residue limit (MRL) except for the first spraying(thiamethoxam:1mg/kg; beta-cyfluthrin:0.5 mg/kg); However, the residue of beta-cyfluthrin in alternating III exceeds the MRL after the last spraying. Since thiamethoxam could be metabolized to clothianidin, dynamic residue of clothianidin was determined. The highest concentration was obtained at 3-5 d after spraying. However, the residue of clothianidin was lower than MRL(0.04 mg/kg) after the pre-harvest interval (PHI); The results of risk assessment of dietary intake showed that in this standardized residue test in Shaoxing, Zhejiang Province, thiamethoxam and beta-cyfluthrin were combined and applied alternatly for three times. After the PHI of 7 d, the contribution rate of thiamethoxam and beta-cyfluthrin residues in celery samples collected to risk quotient (0.11%~3.76%) was lower than 100%, and the long-term dietary intake risk was at an acceptable level. The results showed that compared with combined application, pesticide residues could be reduced to some extent by alternate spraying, and the alternate spraying of thiamethoxam - bata-cyfluthrin - thiamethoxam showed the lowest residue level and contribution rate of dietary intake risk, which was the relatively best application strategy. [ABSTRACT FROM AUTHOR]

In this paper, the effect of single and combined exposure of polystyrene microplastics (PS-MPs) and clothianidin on the germination characteristics of maize seeds was investigated. The results showed that the germination of maize seeds (germination rate, germination energy, germination index, vigor index, root length, and shoot length) was significantly inhibited by 10 mg/L and 100 mg/L PS-MPs with three particle sizes of 0.5, 5, and 50 μm in the single treatment, and the variation in particle size and concentration of PS-MPs had less effect on the germination status of maize seeds. In the single clothianidin treatment, the low concentration (10 mg/L) of clothianidin had no significant effect on the germination of maize seeds, while the high concentration (100 mg/L and 200 mg/L) of clothianidin had a significant inhibitory effect on the germination of maize seeds. Compared with single clothianidin treatment, the combined exposure group with the 100 mg/L PS-MPs with a particle size of 50 μm and 200 mg/L clothianidin decreased the content of clothianidin in maize seeds, alleviating the inhibitory effect of high concentrations of clothianidin on the germination of maize seeds. High concentrations of clothianidin and single PS-MPs exposure inhibited maize seed germination, whereas PS-MPs alleviated the inhibitory effects of high concentrations of clothianidin on seed germination in the combined exposure. [ABSTRACT FROM AUTHOR]

[Objective] To evaluate the residual digestion and dietary intake risks of clothianidin and chlorfenapyr in welsh onion.[Method]By conducting standardized field residue tests and considering the residual levels of clothianidin and chlorfenapyr in welsh onion, the long-term dietary intake risks of clothianidin and chlorfenapyr were evaluated.[Result]The half-lives of clothianidin and chlorfenapyr in welsh onion were 4.6-7.4 and 5.8-6.9 d, respectively, indicating faster degradation. The results of long-term dietary risk assessment indicated that the risk quotients（RQ） of clothianidin and chlorfenapyr in the general population were 5% and 84%,respectively, indicating that the risk of dietary intake was acceptable.[Conclusion]At the recommended dosage, the residues of clothianidin and chlorfenapyr in welsh onion have no effect on human health. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objectives] To determine the resistance of Aphis gossypii to different pesticides and identify those that are safer for Hippodamia variegata. [Methods] The number of A. gossypii and H. variegata larvae and adults in each plot after the application of 13 different pesticides from 8 different types was quantified using the five-point sampling and visual methods. The effect of each pesticide on A. gossypii, the corrected rate of decrease of larvae and adults of H. variegata, and the ratio of H. variegata to A. gossypii, were also measured. [Results] A. gossypii were more susceptible to sulfoxaflor, flonicamid and afidopyropen, which at 3, 7, 10 and 14 days after application had reduced numbers by 73.53%-97.46%, respectively. The ratio of H. variegata to A. gossypii was also higher in plots treated with these pesticides (0.0168-0.0927). With the exception of acetamiprid, dinotefuran and spirotetramat, the other 10 pesticides tested were relatively safer for H. variegata larvae. The effects of all 13 pesticides on H. variegata adults were low; the corrected decrease rate was 6.73%-32.61%. Among the pesticides tested, dinotefuran, clothianidin, thiamethoxam, nitenpyram and pymetrozine had the least effect on H. variegata adults (7.37%-31.00%). Except for imidacloprid (7 days after treatment), acetamipri (3 days after treatment) and dinotefuran (3, 7 and 14 days after treatment), there were no significant differences between the corrected decrease rates of H. variegata larvae and adults among the other pesticides. [Conclusion] Sulfoxaflor, flonicamid and afidopyropen are both more effective than the other pesticides tested for the control of A. gossypii, and safer for H. variegata. Alternating the application of these three pesticides could both reduce the development of resistance in A. gossypii and mortality of H. variegata. [ABSTRACT FROM AUTHOR]

In order to explore the effect of rice seed treatment suspension (FS) on the growth of rice in dry land cultivation. In this paper, two seed treatment suspensions, i.e., sedaxane + pylocyanonitrile + metalaxyl 11% FS and clothianidin 18% FS were selected to treat rice seed (guang8you 1973). The effect of FS was assessed by standard germination, Q2 test, agronomic traits and yield. The results showed that: under laboratory conditions, germination vigor, germination percentage and increased metabolism time (IMT) of two FS with the 1 : 50 treatment (1 mL of agent is required to process 50 g of seeds, referred to as the ratio of FS to seed) had no significant effect on these parameter compare with the blank control under laboratory condition. However, the FS with the 1 : 50 treatment showed a shorter relative germination time (RGT), a higher starting metabolism rate (SMR), and the oxygen metabolism rate (OMR) was significantly higher than that of the blank control by 1.33% and 1.38% per hour, respectively. This results indicate that FS can improve seed respiration and seed vigor. The comparison between the two FS indicate that the clothianidin 18% FS had a better effect on seed vigor than the sedaxane + pylocyanonitrile + metalaxyl 11% FS under the field condition. The field performance was better than that of the blank control, among which the seedling rate of seed coatingagent treatment increased by 27.60%-33.20% compared with CK, the number of tillers increased by 71.14-97.82 per hectare, the plant height increased by 4.90-6.80 cm, the thousand-grain weight increased by 7.27%-9.09%, the effective panicle increased by 9.45-13.42 million panicles per hectare, and the actual yield increased by 529.85 kg/hm2 and 580.70 kg/hm2, and there were significant differences between them. The results showed that: coating rice seeds with sedaxane + pylocyanonitrile + metalaxyl 11% FS and clothianidin 18% FS at a seed ratio of 1 : 50 can effectively promote rice seed respiration, improve the performance and yield in dry land cultivation. [ABSTRACT FROM AUTHOR]

Copyright of Modern Food Science & Technology is the property of Editorial Office of Modern Food Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Organosilicon adjuvant Silwet stik and vegetable oil adjuvant Maisi were selected to conduct field experiments with thiamethoxam to verify the preventive effect on cowpea thrips and residual behavior. Dissipation dynamic and residues of recommended application dose 75, 67.5, 60, and 52.5 g a.i/hm² of 25% thiamethoxam water dispersible granules (WG) with two different adjuvants were compared respectively and the preventive effect of 5 and 7 days after the last spray was investigated. The cowpea samples were extracted by acetonitrile, purified with primary secondary amine (PSA), and detected using high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The results of field tests indicated that the initial deposition of thiamethoxam on cowpea were significantly increased by 8.84% and 6.58% respectively when the adjuvant 0.4% Silwet stik or 0.5% Maisi was added. The control effect against cowpea thrips of 25% thiamethoxam WG added with the two adjuvants above were significantly higher than that without adjuvant 7 days after treatments. Five days after treatments, the addition of adjuvant Silwet stik or Maisi increased preventive effect by 4.04%-8.55% and 10.37%-12.25% respectively, while the recommended application dose of thiamethoxam was reduced by 10%-30%. The results showed that the adjuvant treatments increased the deposition of thiamethoxam on cowpea, which would benefit the synergistic effect of pesticide, and improved control effect on thrips. The study provides evidence for the synergistic control effect of adjuvants and the scientific use of thiamethoxam against cowpea thrips. [ABSTRACT FROM AUTHOR]

A rapid and trace analytical method was established for the determination of thiamethoxam and its metabolite clothianidin in wheat leaves and wheat ears using ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Wheat leaves and wheat ears were extracted with acetonitrile and cleaned up with NH2 /Carb solid phase extraction column to remove impurities such as chlorophyll and starch. The internal standard method was used for quantitation. The results showed that the linearity of thiamethoxam and clothianidin was good in the range of 0.001- 0.5 mg/L, and the correlation coefficient was greater than 0.99. After internal standard correction, the recoveries of thiamethoxam and clothianidin in wheat leaves and wheat ears were in the range from 83.4% to 117.9% at 4 levels of 0.001, 0.01, 0.1 and 1 mg/kg, and the relative standard deviations were in the range of 1.6% to 13.0%. The limit of quantitation was 0.001 mg/kg. This method was used to determine the wheat leaves and wheat ears field samples after the wheat crops were sprayed with thiamethoxam 250 WG by unmanned aerial vehicle (UAV). The concentrations of thiamethoxam in wheat leaves and wheat ears were 4.24 and 1.34 mg/kg, respectively, at 2 h after application. On the 14th day after application, the concentrations of thiamethoxam and clothianidin were 0.097 and 0.079 mg/kg in wheat leaves, and were 0.031 and 0.046 mg/kg in wheat ears, respectively. This method can meet the detection requirements of wheat during the whole growth period, and it can also be used to study the conduction and distribution characteristics and residual metabolism of thiamethoxam and clothianidin in wheat plants. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to provide theoretical basis for guiding scientific use of 18% clothianidin embedding GR and reducing environmental risk, the correlation between the accumulative amount and the control efficacy on whitefly of 18% clothianidin embedding GR and the dynamics of residual dissipation were investigated on greenhouse cucumbers. Under greenhouse conditions, using 1% clothianidin GR as the control agent, the control efficacy of 18% clothianidin embedding GR on whitefly was investigated. An ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was established for the determination of clothianidin residues in cucumber leaves and soil. The accumulative amount of clothianidin in cucumber leaves at different application dosages and different growth stages was determined, and the correlation between the accumulative amount and control efficacy was studied. The results showed that the control efficacy of 18% clothianidin embedding GR on whitefly was 49%- 95%, which was 1.16-2.32 times higher than that of 1% clothianidin GR, and the ideal control efficacy of 18% clothianidin GR granules could be achieved at 450 g a.i./hm² . The residue dissipation dynamic of clothianidin in soil was in accordance with the first-order kinetic equation. The half-life of 18% clothianidin embedding GR was 43-63 days, while that of 1% clothianidin GR was 35 days, which showed that 18% clothianidin embedding GR had a slow dissipation rate in soil. The accumulative amount of clothianidin in cucumber leaves increased with the increase of the dosage of 18% clothianidin embedding GR. Both the cumulative amount and the control efficacy on whitefly showed a trend of first increasing and then decreasing with the passage of the time after application, and reached the highest value on 56th days after application. When the application rates of active ingredients were 450, 600 and 750 g/hm², the maximum accumulation of clothianidin in upper leaves of cucumber were 1.9, 2.2 and 2.8 mg/kg, respectively, and the highest control efficacy were all 90%. The maximum accumulation of clothianidin in middle leaves were 2.2, 2.5 and 3.0 mg/kg, and the highest control efficacy were 94%, 93% and 95%, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Taiwan Agricultural Research is the property of Taiwan Agricultural Research Institute, Council of Agriculture, Executive Yuan and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Modern Food Science & Technology is the property of Editorial Office of Modern Food Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To evaluate the multiple pesticide residues and the contribution to chronic dietary exposure risks in Hainan mango samples, 178 mango samples were analyzed and the contribution to chronic dietary exposure risk (R) for different Chinese populations was calculated. The most frequently detected pesticide groups were strobilurin and neonicotinoid, and the detection rates were higher than 80.00%. According to the MRLs in China, pyraclostrobin in 39 samples, imidacloprid in 34 samples, clothianidin in 5 samples, difenoconazole in 2 samples, methomyl in 1 sample and paclobutrazol in 1 sample exceeded the MRLs. 71.91% of the samples contained two or more pesticide residues, and the number of detected pesticides was up to 8 in some mango samples. The percentage of mango samples with two or more pesticides of strobilurin or neonicotinoid were 23.03% and 16.30%, respectively. Azoxystrobin/pyraclostrobin, imidacloprid/pyraclostrobin, and imidacloprid/azoxystrobin were the most frequently detected pesticide combinations. The values of R were far below 1, which indicated that the contribution of pesticide residues through mango to the chronic dietary exposure risk was extremely low. [ABSTRACT FROM AUTHOR]

A high efficient and simple method for residue analysis of bifenthrin, thiamethoxam and its metabolite clothianidin in wheat and straw was developed. The samples were extracted with acetic acidacetonitrile, purified with anhydrous magnesium sulfate, primary secondary amine (PSA) and GCB, and detected by ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry (UPLC-MS/MS). The results showed that there was a good linear relationship between the peak areas of bifenthrin, thiamethoxam and clothianidin and their mass concentrations in the range of 0.002 5-0.1 mg/L, with R2 greater than 0.99. The recoveries of bifenthrin, thiamethoxam and clothianidin in wheat and straw were 93%-98%, 87%-98% and 87%-98%, respectively, and the relative standard deviations (RSDs) were 0.8%-4.8%, 0.6%-4.1% and 1.0%-3.3%, respectively, when the spiked levels were 0.01, 0.1, 0.5 mg/kg for wheat grain and 0.05, 0.5, 3 mg/kg for straw. The supervised residue trials were carried out in 12 main wheat producing areas in China according to "guideline for the testing of pesticide residues in crops". The 35% suspension concentrate of bifenthrin and thiamethoxam was sprayed once at the dosage of 150 g/hm2 (active ingredient 52.5 g/hm2) at the beginning of wheat aphids bloom. The residual amounts of bifenthrin, thiamethoxam and clothianidin in wheat grains collected on day 14 and 21 after application verified the applicability of the MRL values, and the results of multipoint tests had higher reliability. The results of long-term and short-term dietary exposure risk assessment showed that the dietary exposure risks of bifenthrin, thiamethoxam and clothianidin residues in wheat were acceptable for children aged 1-6 years and the general population. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the residue changes of nitenpyram, thiamethoxam, imidacloprid, clothianidin, dinotefuran and acetamiprid during different apple processing treatments. The effects of apple can, apple jam, apple wine and apple vinegar processing treatments on the residues of 6 neonicotinoids were studied using high performance liquid chromatography (HPLC). The results showed that during the processing of apple can, the residues of 6 neonicotinoids in apple can were significantly reduced compared with the initial concentration. Among them, the process factors of imidacloprid and thiamethoxam in apple can were 0.8, and the process factor of acetamiprid in apple can was the lowest (0.1). In the apple can juice, the process factor of nitenpyram was the highest (0.5), and the process factors of acetamiprid and thiamethoxam were 0.4. During the processing of apple jam, the process factors of nitenpyram, thiamethoxam, imidacloprid, clothianidin, dinotefuran, and acetamiprid were 0.8, 0.9, 0.9, 1.0, 0.9 and 0.9, respectively. During the processing of apple wine, the process factor of imidacloprid was 0.1, and the process factors of all the others were lower than 0.1. During the processing of apple vinegar, the residues of all the pesticides were below the detection limit, except that a small amount of clothianidin residue (0.05 mg/kg) was detected. During the laboratory simulated experiments, the process factors of 6 neonicotinoids were all lower than 1, which indicated that the residue levels were reduced. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To investigate the transformation of neonicotinoids insecticides (thiamethoxam, nitenpyram, imidacloprid, acetamiprid, clothianidin, dinotefuran) in different parts of apple fruits, the selected 10 years old apple trees were sprayed with 6 neonicotinoids insecticides on leaves during the period of the aphid outbreak (July 10th) and the maturation stage before harvest 1 d (September 25th), respectively. The residues and characteristics of 6 neonicotinoids insecticides distribution in different tissues of bagged apple, non-bagged apple and fruits in storage were analyzed by HPLC and external standard method. The results showed that contents of the 6 neonicotinoids insecticides in different tissues of the fruits tended to increase first and the decrease gradually in 72 h after the spraying under the fruit bagged condition. The residues in apple peel were all lower than 0.08 mg/kg, while the residues in pulp and carpopodium were significantly higher than that in the peel. The residues of nitenpyram and imidacloprid in peel were lower than the quantity limit. The results indicated that the neonicotinoids insecticides in bagged fruits derived from the transportation in the branches and leaves, and it went into the fruits via the carpopodium and tended to accumulate in the pulp. 72 h after the spraying, the neonicotinoids insecticide contents in the pulp of then on-bagged fruits was 7.75, 3.52, 3.36, 6.57, 2.92 and 3.06 times higher than those of the bagged fruits, respectively. The fruits bagging could lower down the neonicotinoids insecticide residues in the fruits significantly. After spraying on the fruits at the maturation stage before harvest, the residues were mainly in apple peel. 14 d and 21d after spraying, there was no residue detected in apple pulp. The neonicotinoids insecticide residues mainly remained in the peel, which did not tend to diffuse to the pulp during storage. [ABSTRACT FROM AUTHOR]

Residues and dissipation of clothianidin (20% SC) in pears were investigated in three locations through a two-year field experiment. Clothianidin in pears was determined by utra high performance liquid chromatography with photo-diode array detector. The samples were extracted by acetonitrile, cleaned up by the NH2 column, and quantified by external standard method. At the fortified level of 0.05 to 2.5 mg/kg, the recoveries of clothianidin ranged from 95% to 103% with the relative standard deviations of 2.0% to 3.3%. The limit of quantification (LOQ) of this method was 0.05 mg/kg. The half-lives of clothianidin in pears were 12.0 d to 16.4 d. When the recommended dosage (a.i, 0.06 g/L) and 1.5 times of the recommended dosage (a.i, 0.09 g/L) of clothianidin (20% SC) were sprayed for 2-3 times, the terminal residues of clothianidin ranged from <0.05 mg/kg to 0.13 mg/kg 21 days after the last application. The final residues of clothianidin in pears were lower than the MRL of CAC (0.4 mg/kg). [ABSTRACT FROM AUTHOR]

The residue behaviors of thiamethoxam in Benincasa hispida Cogn. var. chieh-qua How (chieh-qua) were investigated. The residue field trials of thiamethoxam were designed and conducted in Guangdong and Shanghai in 2015. An effective method was developed for the determination of the thiamethoxam and clothianidin. The chieh-qua samples were extracted by acetonitrile, purified with aminopropyl solid phase extraction and detected using HPLC-MS/MS (high performance liquid chromatography-tandem mass spectrometry). The dissipation and terminal residues of thiamethoxam and clothianidin in chieh-qua samples in Guangdong and Shanghai were determined based on the above analytical method. The results indicated that the half-lives of thiamethoxam in chieh-qua was 4.98-5.84 d. The chieh-qua was sprayed 2 to 3 times with 7-10 days spray interval using 25% WG at the dosage 75 and 112.5 g/hm2 during the young fruit period. The samples were collected 3 to 7 days after the last spray. The terminal residues of thiamethoxam and clothianidin were 0.010-0.422 mg/kg and <0.010- 0.020 mg/kg, respectively, which were determined by the conditions above. The risk quotients (RQ) was 0.044, which revealed its low risk. According to the results, it is suggested that the MRL of thiamethoxam in chieh-qua in China should be set as 1 mg/kg. [ABSTRACT FROM AUTHOR]

A two-year field experiment was conducted to study the residue and dissipation dynamics of clothianidin (50% WDG) in tomatoes and soil in three locations. The dispersive solid phase extraction (DSPE) combined with high performance liquid chromatography-tandem mass spectrometry (HPLCMS/ MS) method was developed for the rapid determination of the clothianidin residue in tomatoes and soil. The results indicated that the recoveries at spiked level of 0.005, 0.01 and 0.05 mg/kg in tomatoes were in the range of 90%-121%, with relative standard deviation of 4.0%-4.5% (n=5); and the recoveries for soil samples were in the range of 88%-92%, with relative standard deviation of 3.6%- 5.8% (n=5). The limits of quantitation (LOQ) for clothianidin in tomatoes and soil were both 0.005 mg/kg, which could meet the requirement of max residue limits (MRLs) of clothianidin. The dissipation dynamics of clothianidin in tomatoes fitted the pseudo-first-order kinetics equations, and the half-lives of clothianidin were estimated to be 3.5-17.3 d in tomatoes. If tomatoes were treated three times and interval of 7 days with the available dosage of 60 g/hm2 during the growing season, the final residue of clothianidin is < LOQ-0.32 mg/kg. According to the MRL of Japan, the harvest interval was recommended to be 1 d. [ABSTRACT FROM AUTHOR]

The formula of clothianidin 300SC was optimized by combining the uniform design and the response surface method. Partial least squares quadratic polynomial and stepwise regression quadratic polynomial model were used to analyze the results about the effect of the wetting-suspending agent and the viscosity modifier on the thermal stability. It was indicated that both the two models were capable of predicting the aqueous separation rate after hot storage(ASRHS) with the R2 of 0.9411 and 0.9999, respectively. The two formulas proposed by predicting models for ASRHS were both favorable formulas, of which the ASRHS were lower than 5% and the suspensibilities before and after the hot storage were higher than 92%. Besides, stepwise regression quadratic polynomial model was the better one, along with the average relative errors of predicted values of-4.85%. The optimal conditions were adding T2700, NR1602, xanthan gum and veegum at mass fraction of 3%, 0.4%, 0.22% and 2%. Under the optimal conditions the minimum value of ASRHS was 2.27%±0.08% and the suspensibility before and after hot storage were 92.51%±0.25% and 92.02%±0.46%. Furthermore, favorable dispersibility and flowability were observed under those conditions. Fortunately, no flocculation, agglomerate or knot at the bottom was observed even after hot storage. The ASRHS of samples remained lower than 5% and other performance was also qualified even when the dosage of T2700 was appropriately reduced according to the response surface results. The combination of uniform design and response surface method demonstrated favorable adaptability in the optimization of SC formula. [ABSTRACT FROM AUTHOR]

Clothianidin, belonging to neonicotinoid insecticide with systemic and contact mechanisms, is used to control the invasive pest Frankliniella occidentalis . To identify the resistance risk, we examined the cross-resistance to multiple insecticides and mechanisms of clothianidin resistant population of F. occidentalis . The results showed that F. occidentalis developed a high level of resis-tance to clothianidin (56.8-fold) after selecting for 45 generations. The resistant population of F. occidentalis had medium level of cross-resistance to thiamethoxam, imidacloprid, chlorpyrifos, cyhalothrin and emamectin benzoate (18.6>RR 50 >11.3), and the low level of cross-resistance to phoxim and methomyl, but no cross-resistance to chlorfenapyr and spinosad. The synergists piperonyl butoxide (PBO) and triphenyl phosphate (TPP) had significant synergistic effects on clothianidin in killing the resistant population (CL), Yunnan wild population (YN) and susceptible population (S). Compared with the sensitive population, the CL populations had significantly increased activities of mixed-functional oxidases P 450 (3.6-fold), b 5 (2.9-fold) and O-demethylase (4.9-fold), and carboxylesterase (2.5-fold), with no significant difference in the activities of glutathione S-transferases among CL and S populations. The results highlight the role of increasing mixed-functional oxidases and carboxylesterase in the resistance of F. occidentalis to clothianidin.

To effectively control the damage of Frankliniella occidentalis (Pergande), we evalutated the resistance risk and resistance stability of F. occidentalis to nitenpyram, clothianidin and thiamethoxam. With the method of dipping Phaseolus vuglaris , we selected the resistance populations from the susceptible population with nitenpyram, clothianidin and thiamethoxam, respectively. Both the resistance inheritance and resistance risk were analyzed with the resistance reality hereditary. After 30 generations' selections, the selected-populations showed high level of insecticide resistance to nitenpyram, clothianidin and thiamethoxam, with a resistance ratio of 44.7-fold, 45.5-fold, and 32.7-fold, respectively. The development rate of resistance to clothianidin, nitenpyram, and thiamethoxam reduced in turn, with a resistance reality heritability of 0.1503, 0.1336 and 0.1258, respectively. Stopping selection for 10 continuously generations, the resistance levels of selection resis-tance populations declined slowly, but could not regain the original susceptibility to nitenpyram, clothianidin and thiamethoxam. After resistance selection, the sensitivity of F. occidentalis nymphs to clothianidin, nitenpyram, and thiamethoxam was significantly higher than that of adults. F. occidentalis had the great potential to gain high level resistance to nitenpyram, clothianidin and thiamethoxam. Compared with other two insecticides, the resistance of F. occidentalis to thiamethoxam increased slower and decreased faster. Therefore, using thiamethoxam in nymph stage might be beneficial to effectively control F. occidentalis .

Clothianidin was selected as a model compound for kinetics and mechanistic investigation of the photocatalytic degradation of nicotine insecticides. We assessed the feasibility of the degradation process, and systematically explored the effects of catalyst amount, reaction temperature, substrate concentration, initial solution pH value, and the presence of inorganic anions and cations on the reaction. The results revealed a Langmuir-Hinshelwood interaction of pseudo-first-order kinetics, showing a rate constant of 0.0506 min -1 . The photocatalytic degradation rate was the highest when the amount of catalyst (TiO 2 ) was 3 g·L -1 . It was observed that an increase of reaction temperature or lowering of substrate concentration was beneficial to clothianidin degradation. Additionally, the initial pH value of the solution had an obvious effect on the degradation process. Strong acid and alkali were not conducive and the degradation rate constant was the largest at pH=5. Furthermore, most of the inorganic anions and cations significantly hindered the degradation of clothianidin. Finally, the degradation intermediates were identified by GC/MS, and the reaction pathways at the initial stage of the photocatalytic process were proposed:hydroxylation of parent compound, cleavage of N-N bond in the nitroguanidine group, and cleavage of the C-N bond connected to the nitroguanidine and thiazole rings.