• Korean Journal of Environmental Agriculture
• /
• v.39 no.1
• /
• pp.75-82
• /
• 2020

BACKGROUND: This study was carried out to establish pre-harvest residue limits (PHRLs) of indoxacarb and pymetrozine in broccoli under greenhouse conditions, based on dissipation patterns and biological half-lives of pesticides during 10 days after application. METHODS AND RESULTS: The field studies were conducted in two different greenhouse, located in Chungju-si (Field 1) and Gunsan-si (Field 2). Samples were collected at 0, 1, 2, 3, 5, 7 and 10 days after spraying pesticide suspension. The analytical methods for indoxacarb and pymetrozine using HPLC-DAD were validated by recoveries ranging of 94.3-105.4% and 81.8-96.0%, respectively, and MLOQ (Method Limit of Quantification) of 0.05 mg/kg. Biological half-lives of indoxacarb and pymetrozine were 2.9 and 3.2-3.8 days in broccoli, respectively. The lower 95% confidence intervals of dissipation rate constant of indoxacarb were determined as 0.1508 (Field 1) and 0.2017 (Field 2), whereas those of pymetrozine were calculated as 0.1489 (Field 1) and 0.1577 (Field 2). CONCLUSION: The significant differences were not observed between the dissipation rates of indoxacarb and pymetrozine in broccoli. The major factor affecting residue dissipation was the dilution effect by fast growth. The PHRLs for 10 days prior to harvest were recommended as 30.06 (Field 1) and 18.07 (Field 2) mg/kg for indoxacarb, and 4.84 (Field 1) and 4.43 (Field 2) mg/kg for pymetrozine, respectively.

• The Korean Journal of Pesticide Science
• /
• v.17 no.2
• /
• pp.107-116
• /
• 2013

Polar pesticides like pymetrozine (log $P_{ow}$: -0.18) are known to be difficult to analyze. The analytical method of pymetrozine using hydromatrix included in the official method of KFDA was uncommon and provided ambiguous evidence to confirm both the identity and the quantity. Therefore, precise single residue analytical method was developed in representative crops for using liquid-liquid extraction (LLE). The pymetrozine residue was extracted with methanol from 11 representative crops which comprised apple, blueberry, broccoli, cabbage, cherry, crown daisy, hulled rice, Korean cabbage, potato, rice and watermelon. The extract was purified serially by liquid-liquid extraction (LLE) and silica solid phase extraction (SPE). For rice and hulled rice samples, n-hexane partition was additionally adopted to remove nonpolar interferences, mainly lipids. The residue levels were analyzed by HPLC with DAD, using $C_8$ column. LOQ (limit of quantitation) of pymetroizinie was 1 ng (S/N > 10) and MQL (method quantitation limit) was 0.01 mg/kg. Mean recoveries from 11 crop samples fortified at three levels (MQL, 10 ${\times}$ MQL and 50 ${\times}$ MQL) in triplicate were in the range of 83.1~98.5% with coefficients of variation (CV) of less than 10%, regardless of sample type, which satisfies the criteria of KFDA. The method established in this study could be applied to most of crops as an official and general method for analysis of pymetrozine residue.

• Korean Journal of Food Science and Technology
• /
• v.51 no.4
• /
• pp.316-323
• /
• 2019

It is difficult to analyze pymetrozine in citrus fruits using the hydromatrix method because of its low efficiency of purification and overlap of matrix and pymetrozine peaks. Liquid-liquid extraction can analyze pymetrozine in citrus fruits using dichloromethane. Since low pH interferes with the extraction of pymetrozine, the extracts of citrus fruits were maintained over pH 7.0 by adding borax buffer and 1 N NaOH in the improved method. According to the improved method, citrus fruits (such as lemon, lime, orange, tangerine, and grapefruit) were extracted and purified for HPLC-photo diode array analysis. The results of validation were as follows: $4.360{\mu}g/kg$ of limit of detection, $14.533{\mu}g/kg$ of limit of quantitation, and 0.007 mg/kg of method quantitative limit. Citrus fruits spiked with pymetrozine showed a recovery range from 71.8 to 83.7% and a coefficient of variation below 6%. Thus, the improved method can efficiently analyze pymetrozine in citrus fruits.

• The Korean Journal of Pesticide Science
• /
• v.4 no.3
• /
• pp.75-81
• /
• 2000

These studies were carried out to investigate the toxicities of 38 registered insecticides to the sweetpotato whitefly (Trialeurodes vaporariorum). Insecticide activities were evaluated by testing systemic action and residual effect in the laboratory, and control efficacy in the greenhouse. All experiments were tested at the recommended concentration(ppm) of each insecticides. Insect growth regulators (IGRs), only pyriproxyfen showed over 90% of ovicidal effect. The insecticides that showed over 90% of larvicidal activity oil 3rd nymphal instars were abamectin, acetamiprid, chlorpyrifos-methyl, imidacloprid, pyripoxyfen, and acetamiprid+ethofenprox. Insecticides with 100% adulticidal activity were abamectin, acephate, acetamiprid, benfurcarb, bifenthrin, furathiocarb, endosulfan, fenitrothion, imidacloprid, phenthoate, pymetrozine, acetamiprid + ethofenprox, ethofenprox + diazinon, furathiocarb + difluberlzuron, and triazamate+${\alpha}$-cypermethrin. Abamectin, acetamiprid, imidacloprid, pyriproxyfen, and acetamiprid + ethofenpox showed both residual effect and systemic activity. In tile control efficacy test on B. tabaci, 90% control values were obtained at 11th day after treatment of the insecticides including abamectin, acetamiprid, imidacloprid, pyripoxyfen and acetamiprid + ethofenprox. These results indicate that abamectin, acetamiprid, imidacloprid, pyriproxyfen and acetamiprid + ethofenprox can be used for tile control of B. tabaci in field.

• The Korean Journal of Pesticide Science
• /
• v.4 no.1
• /
• pp.51-58
• /
• 2000

These studies were carried out to investigate the toxicities of 43 registered insecticides to the sweetpotato whitefly(Bemisia tabaci, B. biotype). Insecticide activities were evaluated by testing systemic action and residual effect in the laboratory, and control efficacy in the greenhouse. All experiments were tested at the recommended concentration(ppm) of each insecticides. Insect growth regulators (IGRs), pyriproxyfen and teflubenzuron showed >95% ovicidal effect. The insecticides that showed >95% larvicidal activity on 3rd nymphal instars were abamectin, acetamiprid, imidacloprid, pyriproxyfen, and acetamiprid+ ethofenprox. Insecticides with >95% adulticidal activity were abamectin, acetamiprid, diazinon, endosulfan, fenitrothion, imidacloprid, methidathion, pirimiphos-methyl, pymetrozine, spinosad, acetamiprid+ ethofenprox, cartap kydrochloride+buprofezin, and fenpropathrin+fenitrothion. Abamectin, acetamiprid, imidacloprid, pyriproxyfen, and acetamiprid+ethofenprox showed both residual effect and systemic activity. In the control efficacy test on B. tabaci, 90% control values were obtained at 1st day after treatment of the insecticides including abamectin, acetamiprid, imidacloprid, pyriproxyfen and acetamiprid+ethofenprox but in pyriproxyfen, 90% control value was reached at 7th day after treatment. These results indicate that abamectin, acetamiprid, imidacloprid, pyriproxyfen and acetamiprid+ethofenprox can be used in control for B. tabaci in field.

• The Korean Journal of Pesticide Science
• /
• v.18 no.4
• /
• pp.296-313
• /
• 2014

A QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) multiresidue method was developed for the simultaneous analysis of 124 pesticides in soil by LC-MS. The procedure involved liquid extraction of soil immersed with 0.2N $NH_4Cl$ by acetonitrile with 1% acetic acid, followed by anhydrous $MgSO_4$ and sodium acetate, and dispersive SPE cleanup with $MgSO_4$, primary secondary amine (PSA) and $C_{18}$. The extracts were analyzed with LC-MS/MS in ESI positive mode. Standard calibration curves were made by matrix matched standards and their correlation coefficients were higher than 0.99. Recovery studies for the validation were carried out using two type soils, loam and sandy loam, at four concentration levels (0.005, 0.01, 0.02, and 0.1 mg/kg). The recoveries of pesticides were in the range of 70-120% with < 20% RSD except 4 pesticides, Benfuracarb, Ethiofencarb, Pymetrozine, and Pyrethrin. This result indicated that the method using QuEChERS and LC-MS/MS could be applied for the simultaneous determination of pesticide residues in soils.

• The Korean Journal of Pesticide Science
• /
• v.9 no.4
• /
• pp.380-390
• /
• 2005

This study was carried out for looking into the status of susceptibility of vinyl house insect pests to insecticides. The Thrips (Thrips palmi and Frankliniela occidentalis), Mites (Tetranychus urticae), Aphids (Aphis gossypii) and Whitefly (Trialeurodes vaporariorum) were captured at various areas where the host crop was being cultivated and the susceptibility level of each pest insect was investigated. The susceptibility of each pest insect varied by insect species and areas where they were caught. The tested insecticides showed good control effect to palm thrips in 2000, but in 2003 showed decrease of effect to them. Western flower thrips showed low susceptibility to neonicotinoids, imidacloprid and thiamethoxam, but high to chlorfenapyr, spinosad, emamectinbenzoate and fipronil. Antibiotic insecticides, abamectin and milbemectin, and chlorfenapyr were very effective on mite control and dicofol still had good effectiveness to it despite of long year use. No aphid species showed resistance to pyrethroid and carbamate insecticides. Relatively new insecticides such as imidacloprid, spinosad, pymetrozine were effective to whitefly, but not were organophosphates, carbamates and pyrethroids.

• Korean Journal of Agricultural Science
• /
• v.44 no.3
• /
• pp.348-358
• /
• 2017

The green peach aphid, Myzus persicae, is one of the most serious insect pest and a vector for a multitude of viral diseases to many crops, vegetables, ornamentals, and fruit trees in the world. A large number of aphids can reduce plant vigor and cause defoliation. Many insecticides have been developed and applied to control the green peach aphid. However, this aphid has displayed a remarkable ability to establish resistance to almost every insecticide. We treated 5 different insecticides registered for M. persicae on pepper leaves and investigated the effects of the insecticides by measuring the time it took to achieve 90% control of the aphids. Acetamiprid worked faster than any other insecticides while cyantraniliprole showed the slowest insecticidal effect. Pymetrozine, pyrifluquinazon, and spirotetramet provided 90% control within similar time. Iwol population's control value was higher than any other populations 24 hours after treatment. When five different unregistered insecticides for M. persicae were treated on pepper leaves, no insecticidal effect was found for gamma-cyhalothrin and novaluron and spinosad showed an insecticidal effect of up to 70% in Iwol population only. Although chlorfenapyr and dinotefuran were not registered for M. persicae, their insecticidal effects were found to be 90% or higher.

• Korean journal of applied entomology
• /
• v.48 no.4
• /
• pp.503-508
• /
• 2009

Biological-control-based-integrated-pest-management of major pests occurring on sweet pepper in greenhouse during summer season was tried. As many as 2.1 Orius laevigatus per $m^2$ were released in two times on June 6 and 19, and the population of thrips was kept under control and accordingly the damage was negligible throughout the season. To control aphids, a total of 0.8 Aphidius colemani per $m^2$ were released in four times, 0.2 of them at a time, flonicamid on May 14 and July 18 and pymetrozine on June 14 and September 4 were sprayed on the spots of high aphid occurrence to reduce the release of the wasp, and the density of aphids was kept under control. Whitefly was controlled successfully by releasing a total of 343.4 Amblyseius swirski per $m^2$ in nine times, 38.1 of them at a time, from May 9 until November 12 and dinotefuran was sprayed on November 12 when the density of whitefly increased up to 200 per trap. Tetranichus kanzawai was controlled by both Phytoseiulus persimilis which was released a total of 44.4 per $m^2$ in five times 8.9 of them at a time from May 23 to September 10, and the A. swirski which was released for the control of whitefly.

• Korean Journal of Food Science and Technology
• /
• v.39 no.3
• /
• pp.237-245
• /
• 2007

We tested for residual pesticide levels in agricultural products purchased from 5 provinces within the middle region of Korea during 2006. A Total of 488 samples of 23 different types of agricultural products were analyzed by GC/MS, GC-NPD, and LC/MS/MS. We used multi-analysis methods to analyze for 231 different pesticide types; a single residual pesticides were detected in 92 samples (18.9%), of which 9 samples (1.9%) exceeded the Korea Maximum Residue Limits (MRLs). we detected pesticide residue in more than 50% of the pepper leaf and welsh onion samples. For the welsh onions, 16 among the 30 analyzed samples contained pesticide residue, and 4 samples exceeded the Korea MRLs. Among the 234 kinds of pesticides we tested for, 42 were detected, and 21 of them were detected more than twice. Six pesticide residue types, including cypermethrin, iprodione, fludioxonil, ethoprophos, flutolanil, and lufenuron, exceeded the MRLs. No residual pesticides were detected in 396 of the samples (81.1%), and the residual pesticide levels in 83 samples (17.0%) were lower than the Korea MRLs, indicating that 98.1% of the samples were relatively safe.