Concentration and dissipation of chlorantraniliprole and thiamethoxam residues in maize straw, maize, and soil

Residue dissipation dynamics and dietary risk assessment of emamectin benzoate, chlorantraniliprole, chlorfenapyr, and lufenuron in cabbage

Emamectin benzoate (EB), chlorantraniliprole (CTP), chlorfenapyr (CFP), and lufenuron (LFR) are widely used to control Spodoptera exigua on cabbage. This study is aimed at establishing a universal, sensitive, accurate, and efficient method for the determination of these pesticide residues in cabbage using QuEChERS pretreatment combined with ultra-performance liquid chromatography or gas chromatography-tandem mass spectrometry (UPLC‒MS/MS or GC‒MS/MS). The recoveries of these pesticides (containing metabolites) in cabbage detected by the optimized method ranged between 80.9% and 99.9%, with relative standard deviations (RSDs) of 0.164-12.5%. The limit of quantification (LOQ) of the four pesticides was determined to be 0.01 mg/kg. The standard curve, accuracy, precision, and LOQ of the analysis method all met the requirements of pesticide residue detection. The optimized method was used to detect the dissipation dynamics and terminal residues in 12 regions. The dissipation half-lives of CTP, CFP, and LFR were 3.35-7.01 d, 2.29-4.75 d, and 3.24-6.80 d, respectively. The terminal residues of all these pesticides were below the maximum residue limits (MRLs). The dietary risk assessment indicated that the dietary risk probabilities for EB, CTP, CFP, and LFR were all less than 1 and were within the acceptable range. This study provides a comprehensive assessment of the residues and dietary risks of EB, CTP, CFP, and LFR for the scientific use of pesticides.

Chlorantraniliprole in foods: Determination, dissipation and decontamination

Chlorantraniliprole (CAP) is the first commercially available anthranilic diamide insecticide that targets ryanodine receptors. However, excessive use of CAP can lead to persistent contamination on treated foods and adverse effects on human wellness. The current review focuses on CAP residue analysis in foods by using chromatographic techniques. QuEChERS (quick, easy, cheap, effective, rugged and safe) is the most widely used sample preparation strategy and liquid chromatography tandem mass spectrometry is the predominant analytical method for various food matrices including vegetable, fruit, grain, fish and so on. Moreover, this review summarizes the dissipation pattern of CAP on foods and found it usually dissipates fast on plant in open-field environment. For decontamination, common culinary cleaning methods could effectively remove CAP from vegetables. Finally, some new directions are proposed for better advancement.

Determination of chlorantraniliprole 18.5% SC in the paddy ecosystem and its risk assessment

Chlorantraniliprole belongsto theanthranilic diamide group is widely used against broad range of lepidopteron pests in a variety of vegetable and rice pests includingyellow rice stem borer and leaf folder. Supervised field trials were conducted duringRabi (2018-2019) and Kharif (2019) to evaluate the dissipation pattern and risk assessment of chlorantraniliprole 18.5% SC in paddy ecosystem following foliar application at 30 and 60 g a.i. ha^-1 in two different cropping seasons.Modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) technique was used for the extraction of CAP residues with acetonitrile and determined by LC-MS/MS (ESI +).The limit of quantification (LOQ) was 0.01 µg g^-1 for paddy leaf, straw, husk, and brown rice, respectively and 0.005 µg g^-1 for soil. The average recoveries obtained were 84.30-88.92% from paddy leaf, 94.25-97.81% from straw, 90.21-93.38% from husk, 93.57-96.40% from brown rice and 89.93-91.14% from soil. The residues in paddy leaf dissipated within 35-40 days with a half-life of 4.33-5.07 days in Rabi and 3.92-4.86 days in Kharif at 30 and 60 g a.i. ha^-1, respectively. The residues in soil dissipated within 15-21 days with a half-life of 14.44-15.75 days in Rabi and 13.33-14.44 days in Kharif at respective doses. At harvest chlorantraniliprole residues were not detected in straw, husk, and brown rice. The dietary risk of paddy leaf (green fodder) for cattle was found safe for consumption as the hazard index is less than one. Soil ecological risk assessment was found to be less than one (RQ < 0.1) for earthworms (Eisenia foetida) and arthropods (Aphidiusrhopalosiphi). The presentmethod could be useful inthe analysis ofchlorantraniliproleresidues in different cereals and vegetable crop ecosystems and application at recommended dose is safe for the final produce at harvest.

Dissipation behavior, residue transfer, and safety evaluation of chlorantraniliprole and indoxacarb during tea growing and brewing by ultrahigh-performance liquid chromatography-tandem mass spectrometry

A reliable and simple analytical method was developed and validated to simultaneously determine chlorantraniliprole and indoxacarb in tea using ultrahigh-performance liquid chromatography-tandem mass spectrometry. The average recoveries of chlorantraniliprole were in the range of 86-110%, with the precision of intraday (n = 5) and interday (n = 15) ranging from 1.9 to 8.4% and from 2.4 to 8.8%, respectively. The average recoveries of indoxacarb were in the range 81-105%, with the precision of intraday (n = 5) and interday (n = 15) ranging from 2.0 to 9.8% and from 2.7 to 9.1%, respectively. The limits of quantification (LOQs) were all 0.01 mg/kg. The results based on the supervised field trials showed that chlorantraniliprole and indoxacarb in two tea samples followed first-order kinetics models with half-lives of 2.2-4.7 days and 2.5-3.5 days, which could be regarded as a moderately degrading pesticide. The terminal residues of chlorantraniliprole and indoxacarb in made tea were below 6.7 and 4.5 mg/kg, respectively, lower than their corresponding maximum residue limits (MRLs) established by several major countries and organizations (50 and 5 mg/kg). The leaching rates of chlorantraniliprole and indoxacarb during the tea brewing ranged from 4.78 to 12.62% and 4.13 to 10.67%, respectively. The chronic intake risk quotient (RQc) values for chlorantraniliprole and indoxacarb were 0.24% and 35.10%, while the acute dietary risk assessment (RQa) value of indoxacarb was 5.8%, which were all much lower than 100%. The results in the present study indicated that the health risk posed by the chlorantraniliprole and indoxacarb mixture pesticides was negligible in tea for consumers at the recommended dosages.

Effects of multigenerational imidacloprid and thiamethoxam stress on metabolism and physiology of Aphis glycines Matsumura (Hemiptera: Aphididae)

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), a primary pest of soybean, poses a severe threat to soybean production. In this study, the 4th instar nymphs were exposed to the LC50 and LC30 of imidacloprid and thiamethoxam from F0 to F4 generations to evaluate the activities of peroxidase, pyruvate kinase, and trehalase using microassay. We found that peroxidase and pyruvate kinase activities in soybean aphids increased rapidly, first to peak and then decreased slowly generation by generation under imidacloprid and thiamethoxam stress. In contrast, the trehalase activity was significantly decreased in F1 to F5 generations when treated with the LC50 and LC30 and imidacloprid and thiamethoxam compared to control. In addition, the Enzyme-Linked Immunosorbent Assay (ELISA) was used to monitor the changes in molting and juvenile hormone expressions of the soybean aphids in each generation (F1-F5). The expression of juvenile hormone in soybean aphids was increased significantly in each generation under continuous stress of imidacloprid and thiamethoxam LC50 imidacloprid and LC50 thiamethoxam inhibited the expression of molting hormones in soybean aphids of each generation. LC30 imidacloprid or LC30 thiamethoxam significantly stimulated the expression of molting hormone in the 1st and 2nd instar nymphs in each generation. In this paper, the differences in antioxidant regulation, energy metabolism intensity, and hormone expression of multi-generation soybean aphids were monitored under continuous stress of imidacloprid and thiamethoxam. Our results revealed the effects of continuous insecticide stress on the main endogenous substances. Further, they clarified the regulation rules of resistance in soybean aphids, providing a reference for efficient control with imidacloprid and thiamethoxam.

Timely Application of Four Insecticides to Control Corn Earworm and Fall Armyworm Larvae in Sweet Corn

Insecticide sprays are a common practice to control corn earworm, Helicoverpa zea (Boddie), and fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), in corn (Zea mays L.) at reproductive stages. Our objectives were to determine (1) the most appropriate time for insecticide applications and (2) the effect of four insecticides on the survival of larvae as well as their weight. ß-cyfluthrin (0.4 mL/L), chlorantraniliprole (0.6 mL/L), emamectin benzoate (0.2 g/L), and spinetoram (1.5 mL/L) were sprayed on silks of sweet corn planted in Isabela and Lajas, Puerto Rico 3 h before and 24 and 48 h after pollination. The number of kernels produced and the damage of larvae on kernels were quantified at harvest. In addition, percentages of mortality and changes on larval weight were noted at 96 h after insecticide applications. Insecticide sprays at 3 h before pollination reduced the number of kernels or were similar to the control in all treatments. However, emamectin benzoate sprayed in Lajas and chlorantraniliprole applied in Isabela at 48 h after pollination increased the number of kernels (281−294) and reduced the damage of larvae on kernels (<0.5%) compared to the control (201−229; >7%). Furthermore, applications of emamectin benzoate caused higher percentages of fall armyworm larval mortality (>70%). Conversely, ß-cyfluthrin and chlorantraniliprole caused lower percentages of mortality (<30%) and only chlorantraniliprole and spinetoram reduced the weight of corn earworm and fall armyworm larvae collected in both locations. This information may help pest management programs and corn breeders to schedule insecticide sprays and pollination in the field.

Enrichment of diamide insecticides from environmental water samples using metal-organic frameworks as adsorbents for determination by liquid chromatography tandem mass spectrometry

A series of metal-organic frameworks composed of different metal ions and organic linkers were facilely synthesized and used as adsorbents for five diamide insecticides for the first time. Among them, MIL-101-NH₂ performed much better than other materials due to extraordinarily high specific surface area, strong water stability, specific interaction with analytes. A sensitive method was developed with MIL-101-NH₂ based dispersive solid phase extraction combining with liquid chromatography tandem mass spectrometry (dSPE-LC-MS/MS). Important parameters including adsorbent amount, enrichment time, elution solvent and volume, pH and salt effect were investigated to achieve the best enrichment efficiency. At selected conditions, the proposed method showed ultrahigh sensitivity with limits of detection low to 0.01-0.03 ng/mL, which was 2-3 orders of magnitude lower than reported methods. Wide linearity in the range of 0.03-1000 ng/mL (chlorantraniliprole, cyantraniliprole) and 0.1-2000 ng/mL (flubendiamide, cyclaniliprole, tetrachlorantraniliprole) were established with satisfactory coefficient of determination. The method was successfully used for analyzing of diamide insecticides in environmental water samples and flubendiamide was detected in several samples. This work demonstrated the first example of developing novel nanomaterials in trace amount diamide insecticide enrichment from practical samples, which opens a new perspective in establishing nanomaterial-based sample preparation method for diamide insecticide analysis.

Validation of QuEChERS Method Coupled with LC-MS/MS for Determination of Thiamethoxam and its Metabolites in Wheat and Soil

BACKGROUND

Thiamethoxam, a neonicotinoid insecticide, has been widely accepted for the control of sucking and certain chewing pests. Through different routes, i.e., wind drift, leaching, and surface runoff, it can reach non-target areas, which include humans as well. Therefore the fate of thiamethoxam in food grains and soil is of prime importance, entailing a need for pesticide use to be subject to steady observation.

OBJECTIVE

The review aimed to validate the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method for the detection of thiamethoxam and its metabolites in wheat leaves, grain, straw, and soil using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

METHOD

The QuEChERS method allows sample extraction by acetonitrile followed by cleanup with a primary secondary amine sorbent, magnesium sulphate, and graphitized carbon black. The method was validated in terms of selectivity, linearity, LOD, LOQ, matrix match, accuracy, and precision. The estimation of residues was done by LC-MS/MS.

RESULTS

The recovery of thiamethoxam and its metabolites in wheat and soil samples was in the range of 81.22-98.14%. The LOQ for thiamethoxam and its metabolites was 0.01 mg/kg. The matrix effect values were in the acceptable range of -20 to +20%.

CONCLUSIONS

The method allows a simple and fast extraction of thiamethoxam and its metabolites from wheat leaves, grain, straw, and soil. It could be helpful in the evaluation of regulatory and food safety decisions regarding the use of neonicotinoids.

HIGHLIGHTS

The method was validated according to the European Commission SANTE/12682/2019 guidelines. An accurate, simple, and sensitive analytical method was validated for thiamethoxam and its metabolites.

Soil dissipation of sugarcane billet seed treatment fungicides and insecticide using QuEChERS and HPLC

Chemical treatment of sugarcane seed with fungicides and insecticides prior to planting increases yields of cane and sugar for the perennial, annually harvested crop. However, the fate of the applied chemicals is unknown. Therefore, the purpose of this study was to measure the aerobic dissipation of selected billet seed treatment chemicals in a mineral sugarcane soil from Louisiana. Soil samples from the surface 15 cm were treated with either thiamethoxam, azoxystrobin, fluxapyroxad, propiconazole, or pyraclostrobin and monitored over 100 days under laboratory conditions. Insecticide and fungicide levels were determined by high performance liquid chromatography. Dissipation data were fitted to four kinetic models: simple first-order (SFO), first order multi-compartment (FOMC), double-first order in parallel (DFOP), and hockey-stick (HS). The dissipation half-life (DT₅₀) of thiamethoxam, azoxystrobin, fluxapyroxad, propiconazole, or pyraclostrobin were 275, 100, 144, 74, and 39 d, respectively. Overall, the DT₅₀ for the pesticides in the study indicated medium to long persistence in soil under the conditions of the experiment. This is the first report for several of these pesticides related to the aerobic dissipation in soils used to grow sugarcane.

Quantitative analysis of translocation of tetraniliprole as a seed dresser

To ensure the plant health and safety of natural enemies and pollinators, seed dressing is preferred over foliar application. It is an eco-friendly approach of crop protection at low doses. Tetraniliprole as a seed dresser was applied on maize seeds at 3.6 and 7.2 g a.i./kg as a proposed dose and twice the proposed dose, respectively. The present field study assessed the quantitative translocation of tetraniliprole and its toxic metabolite chinazolinone in maize leaves, immature cob, stove, and grains using the QuEChERS method. The quantification of residue was carried on HPLC equipped with reverse phase ZORBAX Eclipse Plus C18 column (4.6 × 250; 5 μ) and diode array detector. Limit of detection and limit of quantification were worked out to be 0.01 and 0.05 mg kg^-1, respectively. All calibration curves showed a good linear relationship (r² > 0.99) within test ranges (0.01-0.5 μg ml^-1). Samples of maize leaves were collected on the 20th day after sowing considered "0" day. Initial residues of tetraniliprole in maize leaves were 0.921 and 1.377 mg kg^-1 at proposed and twice the proposed dose, respectively, and reached below limit of quantification (LOQ) 0.05 mg kg^-1 on the 7th and 15th day, respectively. Chinazolinone was not detected at both the doses. Estimation of tetraniliprole as well as its metabolite persistivity in immature cob at fruiting stage, mature grain, stove, and soil collected at harvest time revealed residues below LOQ.

Dissipation Kinetics and Environmental Risk Assessment of Thiamethoxam in the Sandy Clay Loam Soil of Tropical Sugarcane Crop Ecosystem

Thiamethoxam 75 SG has recently got registered for use against shoot borer and termites of sugarcane. It is the only neonicotinoid having label claim against both the major pests of sugarcane. The dissipation kinetics and environmental risk assessment of thiamethoxam 75 SG were studied in a typical tropical sugarcane crop ecosystem as detailed reports are lacking. Rapid and sensitive method adopted to determine the residues of thiamethoxam in the soil employing HPLC could provide more than 95.5% recoveries. The insecticide was observed to persist in the sandy clay loam soil for 60 days and reached below the detectable level of less than 0.01 mg/kg (LOQ = 0.01 mg/kg) on 75th day when applied @ 120 g a.i./ha. The half-life was worked out to be 16.50 days. At double the recommended dose (240 g a.i./ha), the insecticide persisted up to 75 days with the half-life of 16.91 days. The risk quotient values indicated medium to low level of risk to earthworms during the course of degradation of thiamethoxam in the soil.

Uptake and dissipation of metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam in greenhouse chrysanthemum

Production of chrysanthemum (Dendranthema grandiflora) in greenhouses often requires intensive pesticide use, which raises serious concerns over food safety and human health. This study investigated uptake, translocation and residue dissipation of typical fungicides (metalaxyl-M and fludioxonil) and insecticides (cyantraniliprole and thiamethoxam) in greenhouse chrysanthemum when applied in soils. Chrysanthemum plants could absorb these pesticides from soils via roots to various degrees, and bioconcentration factors (BCF_LS) were positively correlated with lipophilicity (log K_ow) of pesticides. Highly lipophilic fludioxonil (log K_ow = 4.12) had the greatest BCF_LS (2.96 ± 0.41 g g^-1), whereas hydrophilic thiamethoxam (log K_ow = -0.13) had the lowest (0.09 ± 0.03 g g^-1). Translocation factors (TF) from roots to shoots followed the order of TF_leaf > TF_stem > TF_flower. Metalaxyl-M and cyantraniliprole with medium lipophilicity (log K_ow of 1.71 and 2.02, respectively) and hydrophilic thiamethoxam showed relatively strong translocation potentials with TF values in the range of 0.29-0.81, 0.36-2.74 and 0.30-1.03, respectively. Dissipation kinetics in chrysanthemum flowers followed the first-order with a half-life of 21.7, 5.5, 10.0 or 8.2 days for metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam, respectively. Final residues of these four pesticides, including clothianidin (a primary toxic metabolite of thiamethoxam), in all chrysanthemum flower samples were below the maximum residue limit (MRL) values 21 days after two soil applications each at the recommended dose (i.e., 3.2, 2.1, 4.3 and 4.3 kg ha^-1, respectively). However, when doubling the recommended dose, the metabolite clothianidin remained at concentrations greater than the MRL, despite that thiamethoxam concentration was lower than the MRL value. This study provided valuable insights on the uptake and residues of metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam (including its metabolite clothianidin) in greenhouse chrysanthemum production, and could help better assess food safety risks of chrysanthemum contamination by parent pesticides and their metabolites.

Dissipation Kinetics and the Pre-Harvest Residue Limits of Acetamiprid and Chlorantraniliprole in Kimchi Cabbage Using Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry

The dissipation behaviors of acetamiprid and chlorantraniliprole in kimchi cabbages were studied under open-field conditions. A simple and rapid analytical method was developed using ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The multiple reaction monitoring (MRM) conditions of two pesticides were optimized to quantify and identify the pesticide residues. Sample preparation was performed by the QuEChERS (quick, easy, cheap, effective, rugged, and safe) method. Average recovery rates at the different spiked levels (0.05 and 0.25 mg/kg) were in the range of 103.6-113.9% (acetamiprid) and 80.8-91.2% (chlorantraniliprole), and the relative standard deviations were ≤4.3% for all. The dissipation kinetics were assessed using first-order equations after spraying acetamiprid and chlorantraniliprole individually on kimchi cabbages. The biological half-lives in field 1 and 2 were 5.2 and 6.3 days (acetamiprid) and 10.0 and 15.2 days (chlorantraniliprole), respectively. Based on the dissipation equations, the pre-harvest residue limits (PHRLs) corresponding to each day before harvest were suggested as the guidelines to meet the MRL on harvest day. It was also predicted that the terminal residues observed after multiple sprayings (three and seven days) would be below the MRL when harvested, in compliance with the established pre-harvest intervals.

Cyantraniliprole seed treatment efficiency against Agrotis ipsilon (Lepidoptera: Noctuidae) and residue concentrations in corn plants and soil

BACKGROUND

The black cutworm Agrotis ipsilon is the most destructive early season insect pest of corn. In this study, the control efficiency of cyantraniliprole seed treatment against A. ipsilon was evaluated, and the residual concentrations of cyantraniliprole and its metabolite J9Z38 in the stalks of corn seedlings and soil were investigated.

RESULTS

Plant pot experiments showed that A. ipsilon larval mortality was greater than 92% and that the percentage of corn seedlings damaged by A. ipsilon was less than 24% when corn seeds were treated with cyantraniliprole at 2 and 4 g AI kg^-1 seed. Cyantraniliprole seed treatment at a dosage of 2 g AI kg^-1 seed significantly reduced A. ipsilon infestation compared to chlorantraniliprole and clothianidin seed treatments in corn fields. Cyantraniliprole seed treatment resulted in more persistent control efficiency of A. ipsilon in spring than in summer. Cyantraniliprole and J9Z38 residues in corn stalks and soil degraded more slowly in the spring than in the summer.

CONCLUSION

Cyantraniliprole used as a seed treatment can protect corn plants from A. ipsilon infestations throughout the seedling stage. The high biological activity of cyantraniliprole was consistent with the residue levels of cyantraniliprole in the corn stalks and soil. © 2018 Society of Chemical Industry.

Dissipation of neonicotinoid insecticides imidacloprid, indoxacarb and thiamethoxam on pomegranate (Punica granatum L.)

Neonicotinoid insecticides such as imidacloprid, indoxacarb and thiamethoxam are widely used for control of a large number of insect pests of pomegranate crop. Their residue levels were evaluated on pomegranate fruits over 2 years during the same cropping season. The QuEChERS analytical method in conjunction with LC-MS/MS was validated to analyse the insecticides on pomegranate fruits with peel (whole fruit), without peel (aril) and in the field soil. The method performance was satisfactory with the limit of quantification (LOQ) of 0.005 mg/kg which was below the maximum residue limits (MRLs) in pomegranate for the 3 compounds. A first order reaction kinetics was observed for the three insecticides with the half -life of degradation of 8-11.1 days for imidacloprid; 7.4-8.4 days for indoxacarb and 9.8-14.2 days for thiamethoxam. Though the insecticides are systemic in nature, the residues in the edible pomegranate aril were always < LOQ. The maximum residue levels of imidacloprid on pomegranate was less than its MRL of 1 mg/kg, so the pre-harvest interval (PHI) required was 1 day only. For indoxacarb, 31-42 days PHI was needed for the residues to reduce to its MRL of 0.02 mg/kg. The PHI of thiamethoxam was 46-77 days, the time required for its residues to reduce to its MRL of 0.01 mg/kg. Higher rainfall possibly facilitated faster dissipation of imidacloprid residues from pomegranate whereas indoxacarb and thiamethoxam remained unaffected. The results of the study can be utilized to incorporate these three chemicals in the plant protection program of pomegranate and fixation of MRL in India.

Thiamethoxam, Clothianidin, and Imidacloprid Seed Treatments Effectively Control Thrips on Corn Under Field Conditions

With the widespread adoption of no-tillage technology, outbreaks of thrips have caused serious damage to summer corn fields in China. Therefore, effective control of pest populations is often essential for cost-effective crop production. In this study, experiments were conducted in 2014 and 2015 to determine the control efficacy of seven neonicotinoid insecticide seed treatments against corn thrips and the effects of these treatments on natural enemy population densities and emergence rates, seedling characteristics, and yield of corn. The results showed that among the tested neonicotinoid seed treatments, thiamethoxam (1.0 and 2.0 g active ingredient (AI)/kg of seeds), clothianidin (1.0 and 2.0 g AI/kg of seeds), and imidacloprid (2.0 g AI/kg of seeds) showed the highest control efficacy against corn thrips throughout the corn growing season. Seed treatments with acetamiprid, nitenpyram, dinotefuran, and thiacloprid at rates of 1.0 and 2.0 g AI/kg of seeds were difficult to effectively control thrips on summer corn. Neonicotinoid seed treatments showed no adverse effects on the numbers of spiders and lady beetles. Furthermore, treatments did not negatively influence the seedling growth or development of corn but did prevent yield losses. Therefore, treating corn seeds with thiamethoxam, clothianidin, and imidacloprid can provide effective protection against early-season thrips and reduce yield losses under field conditions.

Evaluation of the Leaching Potential of Anthranilamide Insecticides Through the Soil

The mobility of two relatively new antranilic diamide insecticides, cyanantraniliprole (CY) and cholantraniliprole (CH) in soil was examined, by means of disturbed columns loaded with a typical semiarid Mediterranean soil (Calcaric fluvisol) under laboratory conditions. Both insecticides appeared in leachates, with 52% of CY and 41% of CH of the initial mass added (1 µg g^-1) present. For CY, 21% and 19% were recovered from the upper and bottom layers of the soil, respectively, while for CH, 33% and 22% were recovered from the upper and bottom layers respectively. Based on the calculated half-lives (29 and 27 days for CY and CH, respectively) and their log K _OC (about 2.5 for both), the calculated Groundwater Ubiquity Score (GUS) index was higher than 5 for both, indicating they have the potential to leach. Two transformation products, C₁₃H₉Cl₂N₂O (IN-ECD73) and C₁₉H₁₂BrClN₆O (IN-J9Z38) corresponding to the degradation of CH and CY, respectively were also identified and detected in leachates and soil.

Dissipation of chlorantraniliprole, chlorpyrifos-methyl and indoxacarb-insecticides used to control codling moth (Cydia Pomonella L.) and leafrollers (Tortricidae) in apples for production of baby food

Dissipations of three insecticides: chlorantraniliprole, chlorpyrifos-methyl and indoxacarb in apples were studied following their foliar application on apples intended for production of baby food. The apples were sprayed with formulations for control of codling moth (Cydia Pomonella L.) and leafrollers (Tortricidae). Six experiments were conducted; each insecticide was applied individually on dessert apples. A validated gas chromatography-based method with simultaneous electron capture and nitrogen-phosphorus detection (GC-ECD/NPD) was used for the residue analysis. The analytical performance of the method was satisfactory, with expanded uncertainties ≤36% (a coverage factor, k = 2, and a confidence level of 95%). The dissipations of insecticides were studied in pseudo-first-order kinetic models (for which the coefficient of determination, R ² , ranged between 0.9188 and 0.9897). Residues of studied insecticides were below their maximum residue limits of 0.5 mg/kg at an early stage of growth of the fruit. The half-lives of chlorantraniliprole, chlorpyrifos-methyl and indoxacarb were 16-17, 4-6 and 20-24 days, respectively. The initial residue levels declined gradually and reached the level of 0.01 mg/kg in 1 month for chlorpyrifos-methyl, 2 months for chlorantraniliprole and 2.5 months for indoxacarb. To obtain the insecticide residue levels below 0.01 mg/kg, which is the default MRL for food intended for infants and young children, the application of the studied insecticides should be carried out at recommended doses not later then: 1 month before harvest for chlorpyrifos-methyl, 2 months for chlorantraniliprole and 2.5 months for indoxacarb.

Cyantraniliprole at Sublethal Dosages Negatively Affects the Development, Reproduction, and Nutrient Utilization of Ostrinia furnacalis (Lepidoptera: Crambidae)

To better understand the application prospect of cyantraniliprole against the Asian corn borer, Ostrinia furnacalis, a diet-incorporation bioassay was adopted to determine the toxicity of cyantraniliprole against the fourth instar of O. furnacalis. Moreover, other experiments were conducted to examine effects of sublethal levels of cyantraniliprole on larval development, nutrient utilization, and reproduction. In this study, cyantraniliprole showed a high toxicity to fourth-instar larvae of O. furnacalis at dosages of 0.05 μg/g (LC5), 0.11 μg/g (LC20), 0.20 μg/g (LC40), and 0.26 μg/g (LC50) administered through artificial diet. At three sublethal dosages, cyantraniliprole inhibited larval feeding processes, decreased the relative growth rate, the relative consumption rate, the efficiency of food ingestion, and the efficiency of food digestion, as well as decreased the contents of nutrients such as proteins, lipids, and carbohydrates. All these effects go against to the normal growth of O. furnacalis, including reductions in larval and pupal weight, the extension of the larval and pupal period, the prolongation of the adult preoviposition period, total preoviposition period, and mean generation time, and the reduction of adult longevity, oviposition period, and eggs laid by female adults. Together, these changes resulted in the reduction of the intrinsic rate of increase. Hence, even at sublethal concentrations, cyantraniliprole can affect population dynamics by reducing the survival rate, fecundity, and population parameters. This result provides useful information for developing control strategies for O. furnacalis.