• Molecular & Cellular Toxicology
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• v.3 no.1
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• pp.11-18
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• 2007

Mechanisms of insecticide resistance found in insects may include three general categories. Modified behavioral mechanisms can let the insects avoid the exposure to toxic compounds. The second category is physiological mechanisms such as altered penetration, rapid excretion, lower rate transportation, or increased storage of insecticides by insects. The third category relies on biochemical mechanisms including the insensitivity of target sites to insecticides and enhanced detoxification rate by several detoxifying mechanisms. Insecticides metabolism usually results in the formation of more water-soluble and therefore more readily eliminated, and generally less toxic products to the host insects rather than the parent compounds. The representative detoxifying enzymes are general esterases and monooxygenases that catalyze the toxic compounds to be more water-soluble forms and then secondary metabolism is followed by conjugation reactions including those catalyzed by glutathione S-transferases (GSTs). However, a change in the resistant species is not easily determined and the levels of mRNAs do not necessarily predict the levels of the corresponding proteins in a cell. As genomics understands the expression of most of the genes in an organism after being stressed by toxic compounds, proteomics can determine the global protein changes in a cell. In this present review, it is suggested that the environmental proteomic application may be a good approach to understand the biochemical mechanisms of insecticide resistance in insects and to predict metabolomic changes leading to physiological changes of the resistant species.

• Korean journal of applied entomology
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• v.34 no.2
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• pp.89-94
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• 1995

Resistance mechanism of organophosphorus insecticides (OPs) in the spiraea aphid, whose populations were originated from several apple orchards where various OPs were frequently sprayed, was investigated. For Wonju population to which insecticides were not sprayed, resistance ratios (BRs) for pirimicarb, phosphamidon, and demeton S-methyl re 49, 31, and 5, respectively. However, for Yesan population to which OPs were sprayed 5 times, RRs for pirimicarb, phosphamidn, and dementon were 830, 536, and 204, respectively. The esterase activities of Wonju and Yesean populations increased by 44.5 and 92.0% compare to that of Kwagju population. R/S a values (S clone Kwangju population; R clone: Iechon opulation) for acetylcholinesterase (AChE) inhibition (${I}_{50}$) by pirimicarb and phosphamidon were 299.2 and 186.0, respectively. Our results indicate that increase of esterase activity and reduction of AChE sensitivity seemed to contribute insecticide resistance of the spiraea aphid.

• The Korean Journal of Zoology
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• v.3 no.1
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• pp.9-12
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• 1960

The present status of insecticide resistance of Korean mosquitoes is still unknown. The experiment cited below is a part of our series of resistance tests on Korean mosquitoes. The test was carried out during the summer of 1959 to ascertain the degree of resistance of Culex pipiens to insecticides currently used. Culex pipiens eggs were collected from ditches in Seoul City and reared in laboratory with media consisted of the following : Distrilled water 1.0 liter, Magnesium sulfate (MgSO$_4$.7$H_2O$) 1.0gram , Calcium sulfate (CasO$_4$.2$H_2O$) 0.5gram ; Sodium cholride 0.5 gram. A Sufficient amount of beer yeast was also used as a larvar food. Late third and early fourth instar larvae were selected for testing. The results are summarized in the following. THe LC-50 of Culex pipiens to insecticides were 0.061 ppm in p, p-DDT , 0.045 ppm in ${\gamma}$-BHC and0.029 ppm in malathion. Comparing these with LC-50 doses of Orlando laboratory strain, it can be pointed out that the present resistance of Seoul strain shows about a ten-fold increase in DDt, and a fourfold increase in ${\gamma}$-BHC . The resistance development of the Seoul strain has, however, not arisen so markedly as compared with data observed in other parts of Far Eastern areas received heavy insecticidal operations.

• Parasites, Hosts and Diseases
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• v.58 no.5
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• pp.543-550
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• 2020

Mosquitoes are globally distributed and important vectors for the transmission of many human diseases. Mosquito control is a difficult task and the cost of preventing mosquito-borne diseases is much lower than that for curing the associated diseases. Thus, chemical control remains the most effective tool for mosquito. Due to the long-term intensive use of insecticides to control mosquito vectors, resistance to most chemical insecticides has been reported. This study aimed to investigate the relationship between insecticide resistance and target site mutation of L1014 kdr and G119 ace alleles in 5 species/species group of mosquitoes (Aedes vexans, Ae. albopictus, Anopheles spp., Culex pipiens complex, and Cx. tritaeniorhynchus) obtained from 6 collection sites. For Anopheles spp., the proportion of mosquitoes with mutated alleles in L1014 was 88.4%, homozygous resistant genotypes were observed in 46.7%, and heterozygous resistant genotypes were observed in 41.8%. For the Cx. pipiens complex and Cx. tritaeniorhynchus species, homozygous resistant genotypes were found in 25.9% and 9.8%, respectively. However, target site mutation of L1014 in the Ae. vexans nipponii and Ae. albopictus species was not observed. Anopheles spp., Cx. pipiens complex, and Cx. tritaeniorhynchus mosquitoes were resistant to deltamethrin and chlorpyriphos, whereas Ae. vexans nipponii and Ae. albopictus were clearly susceptible. We also found a correlation between the resistance phenotype and the presence of the L1014 kdr and G119 ace mutations only in the Anopheles spp. population. In this study, we suggest that insecticide resistance poses a growing threat and resistance management must be integrated into all mosquito control programs.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2001.05a
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• pp.32-32
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• 2001

• Korean journal of applied entomology
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• v.30 no.2
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• pp.117-123
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• 1991

Acetylcholinesterase(AChE) and esterase activities as mechanisms of resistance to fenobucarb, carbofuran and diazinon in the insecticide-selected brown planthopper strains were investigated. Although there was no significant difference in AChE activity from suscept tible and resistant strains, AChE insensitivity was highly increased in the carbam없e insecticide-selected strains. On the other hand, esterase activity was moderately increa잃d in all the s selected strains. It is concluded that the cross-resistance and the level of resistance in the b brown planthopper can be explained by the combination of altered AChE and high esterase a activity, although a possible involvement of other factor(s) can not be excluded.

• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.829-840
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• 2023

Various chemical pesticides are used to control diamondback moths, Plutella xylostella, which are agricultural pests that occur in cruciferous crops worldwide and cause economic losses. However, due to pesticide misuse, resistance to P. xylostella is consistently reported domestically and internationally. Therefore, we aimed to monitor and map regional resistance to devise efficient and economical control methods for P. xylostella in Korea. This study selected eight highly used insecticides among those registered against P. xylostella. P. xylostella were collected from three cities in the Gyeonggi and Yeongnam Provinces to evaluate insecticide resistance. As a result of experiments with populations collected from Yeoju, Gyeonggi Province, resistance ratios were 114.88, 54.75, 119.00, and 64.00 times higher than the susceptible population with methoxyfenozide, indoxacarb, cyantraniliprole, and fluxametamide, respectively. The resistance ratios of the Yongin population in Gyeonggi Province were 166.33 times with cyantraniliprole and 195.25 times with fluxametamide higher than the susceptible population. The Pocheon population in Gyeonggi Province showed a resistance ratio 283.23 times higher than methoxyfenozide. As a result of experiments with populations collected from Gimhae and Sangju, Yeongnam Province, the resistance ratios of the Gimhae population were 80.97, 138.00, and 89.50 times higher than the susceptible population with methoxyfenozide, cyantraniliprole, and fluxametamide, respectively. Meanwhile, the resistance ratios of the Sangju population were 85.83, 224.67, and 303.25 times higher than the susceptible population with methoxyfenozide, cyantraniliprole, and fluxametamide, respectively. The Yeongnam Province Tongyeong population showed a resistance ratio 367.28 times higher to methoxyfenozide.

• Korean journal of applied entomology
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• v.26 no.3 s.72
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• pp.165-170
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• 1987

This experiment was carried out to evaluate the difference in the biochemical characteristic of the brown planthoppers of the insecticide risistant, susceptible strains and their hybrid progenies. Activity of the esterase isozyme separated by electrophoresis method was remarkably high in the resistant strain as compared with the susceptible strain. Esterase activity between the insecticide-treated strains and the non-insecticide strains was not degraded in the resistant strain and the $F_1$, but remarkably degraded in the susceptible strain. The increase of esterase activity was associated with the development of resistance, and that was inherited with a dominant gene.

• Korean journal of applied entomology
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• v.32 no.3
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• pp.259-264
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• 1993

The experiment was carried out to investigate Insecticide susceptibility of the spiraea aphid (Aphis citricola) in apple orchards In Korea, using dipping method. Although insecticIde susceptibility vaned with local and seasonal populations, the susceptibility to demeLon S-rnethyl and phosphamidons was different from that Lo the other insecticides. The LCso values were 10 ppm for deltamethrin and chloropyrifos, 103 ~ 629 ppm for demeton S-methy1, acephate, phosphamidon, monocrotophos and vamldothion, 12,200 ppm for EPN, and 1,745 ppm for pirimicarb. 'When Insecticide susceptibility was compared between the S-clone selected from a population on the host plant spiraea and the R-clone selected from a population on the apple tree, the resistance ratio as expressed by RIS ratio of $LC_{50}$ was 78 for phosphamidon and 546 for pirimicarb. Esterase zymogram determined by the agar gel electrophoresIs revealed a significant difference between the clones. The activity of the E2, E5, E6 and E7 of the R-clone was higher than that of the S-clone, It is suggesLed that the Increased esterase activity may be involved in the mechanism of insecticide resistance in the spiraea aphid, although the involvement of other factor(s) may not be ruled out.

• Journal of Microbiology and Biotechnology
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• v.28 no.6
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• pp.976-986
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• 2018

Knowledge about the gut bacterial communities associated with insects is essential to understand their roles in the physiology of the host. In the present study, the gut bacterial communities of a laboratory-reared insecticide-susceptible (IS), and a field-collected insecticide-resistant (IR) population of a major rice pest, the brown planthopper Nilaparvata lugens, were evaluated. The deep-sequencing analysis of the V3 hypervariable region of the 16S rRNA gene was performed using Illumina and the sequence data were processed using QIIME. The toxicological bioassays showed that compared with the IS population, IR population exhibited 7.9-, 6.7-, 14.8-, and 18.7-fold resistance to acephate, imidacloprid, thiamethoxam, and buprofezin, respectively. The analysis of the alpha diversity indicated a higher bacterial diversity and richness associated with the IR population. The dominant phylum in the IS population was Proteobacteria (99.86%), whereas the IR population consisted of Firmicutes (46.06%), followed by Bacteroidetes (30.8%) and Proteobacteria (15.49%). Morganella, Weissella, and Enterococcus were among the genera shared between the two populations and might form the core bacteria associated with N. lugens. The taxonomic-to-phenotypic mapping revealed the presence of ammonia oxidizers, nitrogen fixers, sulfur oxidizers and reducers, xylan degraders, and aromatic hydrocarbon degraders in the metagenome of N. lugens. Interestingly, the IR population was found to be enriched with bacteria involved in detoxification functions. The results obtained in this study provide a basis for future studies elucidating the roles of the gut bacteria in the insecticide resistance-associated symbiotic relationship and on the design of novel strategies for the management of N. lugens.