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Kafle L.,National Taiwan University | Wu W.-J.,National Taiwan University | Kao S.-S.,Taiwan Agricultural Chemicals and Toxic Substances Research Institute | Shih C.-J.,National Taiwan University
Pest Management Science | Year: 2011

BACKGROUND: Combining biological control and chemical control could be used for controlling red imported fire ant (RIFA), Solenopsis invicta, more effectively. Beauveria bassiana F256, a local strain from Taiwan, was evaluated for its efficacy in the control of S. invicta under both laboratory and field conditions. RESULTS: The efficacies of different doses of B. bassiana (Bb) using direct application and bait formulation methods were compared. The number of RIFA workers killed by the direct application of Bb or by bait were significantly higher than those of the control, with different rates of efficacy under laboratory conditions. Under field conditions, the direct application of Bb into RIFA mounds was more efficient in inactivating the mounds than the bait application. CONCLUSION: It was shown that B. bassiana is able to control S. invicta under both laboratory and field conditions and can be used as a biocontrol agent against RIFA in Taiwan. © 2011 Society of Chemical Industry.


Vontas J.,University of Crete | Hernandez-Crespo P.,CSIC - Biological Research Center | Margaritopoulos J.T.,University of Thessaly | Ortego F.,CSIC - Biological Research Center | And 3 more authors.
Pesticide Biochemistry and Physiology | Year: 2011

Tephritid flies attack a large variety of fruits, which constitute highly-priced commodities in many countries. Insecticides have been used extensively for their control. Although resistance development in fruit flies has not kept pace with that in other insects, possibly due to their high mobility and tendency for wide spatial dispersal, recent studies have indicated that selection pressure has now reached the point where resistance is detectable in the field and control may therefore become problematic. The status of resistance to the commonly used insecticides in the most significant Tephritid pests, such as the Mediterranean fruit fly Ceratitis capitata, the oriental fruit fly Bactrocera dorsalis, the olive fly Bactrocera oleae and the melon fly Bactrocera cucurbitae, is reviewed. Emphasis has been placed on the resistance mechanisms that have been elucidated at the biochemical and molecular level. Prospects for using this knowledge alongside genomic information in Tephritidae to develop novel strategies of potential practical importance for resistance management are discussed. © 2011 Elsevier Inc.


Huang C.-F.,China Medical University at Taichung | Lin Y.-S.,China Medical University at Taichung | Chiang Z.-C.,China Medical University at Taichung | Lu S.-Y.,Taiwan Agricultural Chemicals and Toxic Substances Research Institute | And 4 more authors.
Journal of Nutritional Biochemistry | Year: 2014

We previously observed a higher incidence of congenital malformations in the fetuses of dams fed an oxidized frying oil (OFO)-containing diet during pregnancy. In this study, we hypothesized that, during pregnancy, maternal ingestion of OFO, specifically the oxidized components (i.e. the polar fraction), modulates peroxisome proliferator-activated receptor (PPARα) or aryl hydrocarbon receptor (AhR) transactivity, altering the metabolism of retinoic acid (RA), a well-characterized morphogen, resulting in teratogenesis. Pregnant C57BL/6J mice were divided into four groups which, from d1 (conception) to d18, were fed a diet containing 10 g/100 g of fresh soybean oil (SO), OFO or the non-polar (NP) or polar (PO) fraction of OFO. Reporter assays testing the transactivity of PPARα and AhR showed that free fatty acids from OFO, specifically the PO fraction, up-regulated PPARα transactivity and down-regulated AhR transactivity. In vivo study showed that the PO fraction group had a significantly higher number of dead fetuses and resorptions per litter than the SO and NP fraction groups. The incidence of abnormalities in terms of gross morphology and skeletal ossification of the fetus was greatest in the PO fraction group, followed by the OFO group, both values being significantly higher than in the other two groups. Hepatic expression of genes encoding enzymes associated with RA synthesis and catabolism in dams and fetuses was differentially affected by PO fraction assault. We conclude that OFO-mediated teratogenesis is associated with disturbed RA metabolism in the dams and fetuses caused, at least in part, by modulation of PPARα and AhR transactivity by the oxidized components in OFO. © 2014 Elsevier Inc.


Hsu J.-C.,National Taiwan University | Feng H.-T.,Taiwan Agricultural Chemicals and Toxic Substances Research Institute | Wu W.-J.,National Taiwan University | Geib S.M.,U.S. Department of Agriculture | And 2 more authors.
Insect Biochemistry and Molecular Biology | Year: 2012

Spinosad-resistance mechanisms of Bactrocera dorsalis, one of the most important agricultural pests worldwide, were investigated. Resistance levels to spinosad in a B. dorsalis strain from Taiwan were more than 2000-fold, but showed no cross resistance to imidacloprid or fipronil. Combined biochemical and synergistic data indicated that target-site insensitivity is the major resistance component. The gene encoding the nAChR subunit alpha 6 (Bdα6), the putative molecular target of spinosad, was isolated using PCR and RACE techniques. The full-length cDNA of Bdα6 from spinosad-susceptible strains had an open reading frame of 1467 bp and codes for a typical nAChR subunit. Two isoforms of exon 3 (3a and 3b) and exon 8 (8a and 8b), and four full-length splicing variants were found in the susceptible strain. All transcripts from the spinosad-resistant strain were truncated and coded for apparently non-functional Bdα6. Genetic linkage analysis further associated spinosad-resistance phenotype with the truncated Bdα6 forms. This finding is consistent with a previous study in Plutella xylostella. Small deletions and insertions and consequent premature stop codons in exon 7 were associated with the truncated transcripts at the cDNA level. Analysis of genomic DNA sequences (intron 2 and exons 3-6) failed to detect exon 5 in resistant flies. In addition, a mutation in Bdα6 intron 2, just before the truncated/mis-splicing region and in same location with a mutation previously reported in the Pxylα6 gene, was identified in the resistant flies. RNA editing was investigated but was not found to be associated with resistance. While the demonstration of truncated transcripts causing resistance was outlined, the mechanism responsible for generating truncated transcripts remains unknown. © 2012 Elsevier Ltd.


Hsu J.-C.,National Taiwan University | Huang L.-H.,Taiwan Agricultural Chemicals and Toxic Substances Research Institute | Feng H.-T.,Taiwan Agricultural Chemicals and Toxic Substances Research Institute | Feng H.-T.,Bureau of Animal and Plant Health Inspection and Quarantine | Su W.-Y.,Taiwan Agricultural Chemicals and Toxic Substances Research Institute
Journal of Pest Science | Year: 2015

Organophosphate (OP) insecticides have been an effective control of several tephritid pests. Recently, OP resistance has been observed in various fly species from different localities. However, in cases where resistance to an OP is exhibited in the field, evaluations of the efficiency of trapping with lures mixed with the same OP toxicants have not been carried out. To address this, the trapping and killing efficiency of lures with OP toxicants was assessed for flies from lines of Bactroceradorsalis exhibiting resistance and susceptibility to OP insecticides. Specifically, bioassays were conducted with males from susceptible, resistant, and revertant lines (derived by relaxation of selection in the resistant line). The trapping and killing efficiencies of traps containing concentrations of 5 or 2.5 % naled were assayed at different exposure times. For the susceptible line, the number of dead flies found inside and outside of the trap was significantly lower than that of the other two tested lines. The number of dead flies found outside was significantly lower for the 2.5 % naled concentration compared to that of the 5 % concentration. Additionally, an analysis of genotypes showed that in trapped males, the frequencies of alleles of the acetylcholinesterase gene associated with resistance were lower compared to males of the field population collected from the same localities. In conclusion, for cases where fly lines exhibit insecticide resistance, the use of toxicant lures laced with the same insecticides may severely impact trapping effectiveness and may result in further increases of the frequency of resistant genotypes in the population. © 2014, Springer-Verlag Berlin Heidelberg.


Hsu J.-C.,National Taiwan University | Feng H.-T.,Taiwan Agricultural Chemicals and Toxic Substances Research Institute | Haymer D.S.,University of Hawaii at Manoa | Chen Y.-H.,Taiwan Agricultural Chemicals and Toxic Substances Research Institute
Pesticide Biochemistry and Physiology | Year: 2011

Genetic and biochemical factors leading to resistance to various organophosphate (OP) based insecticides were studied in lines selected for OP-resistance in the oriental fruit fly Bactrocera dorsalis. Lines were separately selected for resistance to naled, trichlorfon, fenitrothion, fenthion, formothion, and malathion. Overall, these lines showed increased resistance ratios ranging from 13.7- to 814-fold relative to a susceptible (S) line. Also, in these newly selected lines the same three point mutations in the ace gene, previously identified in resistance studies and designated as I214V, G488S and Q643R, were found. As expected, the enzyme from the resistant lines showed lower overall activity and reduced sensitivity to inhibition by fenitrothion, methyl-paraoxon and paraoxon compared to the wild type acetylcholinesterase (AChE) enzyme. The apparent Vmax values for esterase from the resistant lines were 1.2-3.69 times higher than that of the S line. Although only the naled-, trichlorfon- and fenthion-r lines showed lower esterase affinities (based on apparent Km values) compared with the S line, all of the Vmax/Km ratios were higher in the resistant lines compared to that of the S line. The OP-resistant lines also displayed an overall similar pattern of isozyme expression, except for one additional band found only in the naled-r line and one band that was absent in the trichlorfon-, malathion-, and fenthion-r lines. Our results also show that overall, multiple examples of high OP resistance in selected lines of B. dorsalis exhibiting the same genetic alterations in the ace gene seen previously resulted in different effects on esterase enzyme activity in relation to various OP compounds. © 2011 Elsevier Inc.


Hsu J.-C.,National Taiwan University | Chien T.-Y.,National Taiwan University | Hu C.-C.,National Taiwan University | Chen M.-J.M.,National Taiwan University | And 4 more authors.
PLoS ONE | Year: 2012

Insecticide resistance has recently become a critical concern for control of many insect pest species. Genome sequencing and global quantization of gene expression through analysis of the transcriptome can provide useful information relevant to this challenging problem. The oriental fruit fly, Bactrocera dorsalis, is one of the world's most destructive agricultural pests, and recently it has been used as a target for studies of genetic mechanisms related to insecticide resistance. However, prior to this study, the molecular data available for this species was largely limited to genes identified through homology. To provide a broader pool of gene sequences of potential interest with regard to insecticide resistance, this study uses whole transcriptome analysis developed through de novo assembly of short reads generated by next-generation sequencing (NGS). The transcriptome of B. dorsalis was initially constructed using Illumina's Solexa sequencing technology. Qualified reads were assembled into contigs and potential splicing variants (isotigs). A total of 29,067 isotigs have putative homologues in the non-redundant (nr) protein database from NCBI, and 11,073 of these correspond to distinct D. melanogaster proteins in the RefSeq database. Approximately 5,546 isotigs contain coding sequences that are at least 80% complete and appear to represent B. dorsalis genes. We observed a strong correlation between the completeness of the assembled sequences and the expression intensity of the transcripts. The assembled sequences were also used to identify large numbers of genes potentially belonging to families related to insecticide resistance. A total of 90 P450-, 42 GST-and 37 COE-related genes, representing three major enzyme families involved in insecticide metabolism and resistance, were identified. In addition, 36 isotigs were discovered to contain target site sequences related to four classes of resistance genes. Identified sequence motifs were also analyzed to characterize putative polypeptide translational products and associate them with specific genes and protein functions. © 2012 Hsu et al.


PubMed | Taiwan Agricultural Chemicals and Toxic Substances Research Institute, National Taiwan University and U.S. Department of Agriculture
Type: | Journal: Pesticide biochemistry and physiology | Year: 2016

Compared to other organophosphate-resistant and -susceptible (S) lines of Bactrocera dorsalis, the carboxylesterase (CBE) BdE5 in the naled-resistant (nal-r) line has been found to possess remarkable quantitative elevation. Our study attempts to identify the role of BdE5 in naled resistance, and we discovered several points of interest. Firstly, activity staining on native PAGE revealed that the percentage of flies with intensive BdE5 bands in the nal-r line was substantially higher than in the S line, indicating that the BdE5 band correlates with naled susceptibility. Secondly, in vitro and in vivo inhibition assays showed that BdE5 was inhibited by naled in both lines; under diagnostic doses of naled, the overall extent of inhibition on CBEs was much greater in the S line than in the nal-r line. Thirdly, NanoLC-nanoESi-MS/MS analysis used the NCBI database to identify and annotate BdE5 as an esterase FE4-like (XP_011200445.1) in B. dorsalis. Fourthly, rapid amplification of cDNA ends was used to obtain the 2012-bp full-length BdE5 cDNA, which contained an open reading frame of 1770bp and encoded a putative protein of 590 amino acid residues. Phylogenetic analysis revealed that BdE5 is a secreted -esterase (E clade) closely related to CG6414 (NP_570089), a CBE in Drosophila melanogaster. Finally, our relative quantification real-time PCR data showed a significant elevation in transcript levels of the BdE5 gene in nal-r line. Our results confirmed that BdE5 is correlated with naled resistance and provides further understanding about the identification and molecular characteristics of BdE5 in B. dorsalis.


Wang C.-K.,National Health Research Institute | Chang L.W.,National Health Research Institute | Chang H.,Chung Shan Medical University | Yang C.-H.,Taiwan Agricultural Chemicals and Toxic Substances Research Institute | And 3 more authors.
European Respiratory Journal | Year: 2010

Cooking oil fumes (COF) are known to be associated with respiratory diseases and risk of lung cancer. Involvement of trans,trans-2,4-decadienal (tt-DDE), a major component in COF, is suspected. Male CD-1® (ICR) mice were intratracheally instilled with either 8 or 24 mg·kg-1 tt-DDE weekly for 8 weeks. Total numbers and types of cells in bronchoalveolar lavage fluid (BALF), as well as pathological changes, and inflammatory gene modulations in the lung tissues were assessed. We demonstrated that the number of alveolar macrophages in the BALF was significantly increased in tt-DDE-exposed animals. Histologically, there was a dose-correlated increase in epithelial hyperplasia and granulomatous nodules at the bronchioloalveolar junctions (BAJ). Although both Clara and alveolar type II cells were present in the BAJ lesion, only Clara cells were actively proliferative. However, only alveolar type II cells were found in the BAJ granulomatous nodules. Enhanced accumulation of phosphorylated signal transducer and activator of transcription 3 (pSTAT3), a known pro-carcinogenic factor, was also detected in many alveolar type II cells at the BAJ lesions. As both BAJ hyperplasia and enhanced pSTAT3 accumulation are known risk factors associated with increased lung adenocarcinoma development, these findings suggest that tt-DDE may pose a risk in lung carcinogenesis. Copyright©ERS Journals Ltd 2010.


Lin C.-H.,National Chung Hsing University | Lin C.-H.,Taiwan Agricultural Chemicals and Toxic Substances Research Institute | Yan C.-T.,Chung Shan Medical University | Kumar P.V.,National Chung Hsing University | And 2 more authors.
Analytical and Bioanalytical Chemistry | Year: 2011

Metabolites of synthetic pyrethroids such as cis-3-(2,2-dibromovinyl)-2,2- di-methylcyclo-propane-1-carboxylic acid, cis- and trans-3-(2,2-dichlorovinyl)- 2,2-dimethylcyclopropane-1-carboxylic acid), 3-phenoxybenzoic acid (3-PBA), and 4-fluoro-3-PBA are biomarkers for exposure to phenothrin, tetramethrin, cyfluthrin, cypermethrin, deltamethrin, and permethrin. In this study, the pyrethroid metabolites in workers' urine samples were monitored for the first time with a novel sample pretreatment process combining hollow fiber liquid phase microextraction (HF-LPME) and in-syringe derivatization (ISD) followed by gas chromatography-electron capture detector (GC-ECD) analysis. A micro-syringe pre-filled with derivatizing agents and syringe needle connected to an extracting solvent impregnated hollow fiber segment was used as the LPME probe. Pyrethroid metabolites were extracted and enriched simultaneously from urine samples by HF-LPME sampling and acid hydrolysis at 70 °C for 10 min. After sampling, the ISD was performed by mixing the extracting solution and derivatizing agents through plunger movements, followed by GC-ECD analysis. Parameters influencing the HF-LPME efficiency and ISD were investigated and optimized. Under optimum conditions, the method provided enrichment factors of 69.8-154.6, repeatability from 5.0 to 12% (n∈=∈5), and good linearity (R 2∈=∈0.9980-0.9998) for interested analytes spiked in urine samples. The method detection limits ranged from 1.6 to 17 ng/mL. A comparison was performed between the proposed method and conventional methods. The proposed method was applied to analyze pyrethroid metabolites in the urine samples collected from workers of pesticide formulation plants. The results suggested that the proposed HF-LPME coupled ISD method was a rapid, simple, efficient, and eco-friendly technique in the biomonitoring of metabolites of pyrethroids in workers' urine. © 2011 Springer-Verlag.

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