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1.
Artigo em Inglês | MEDLINE | ID: mdl-30641133

RESUMO

Arginine kinase (AK) plays a critical role in insect energy metabolism and has been proposed to be a potential insecticide target for commercial exploitation. In this study, the full length cDNA encoding a typical group 1 insect AK (FoAK) was isolated from the western flower thrips (WFT), Frankliniella occidentalis (Pergande). Sequence analysis showed that FoAK contains an open reading frame of 1068 nucleotides, which encods a protein of 355 amino acid residues including the signature sequence pattern of ATP-guanidino kinases. Genomic structure analysis showed that the coding region of FoAK contains five exons connected by four introns. RT-qPCR analysis revealed that the mRNA expression of FoAK was developmentally regulated with the lowest level in prepupal stage. Enzymatic activity analysis of the recombinant enzymes expressed in Escherichia coli showed that FoAK is highly stereo specific for L-arginine versus D-arginine and the apparent Michaelis constant for L-arginine (KmArg) is comparable to that of AKs from a variety of species. This research should enable further investigation of the function as well as in vitro screening for inhibitors of FoAK.


Assuntos
Arginina Quinase , Expressão Gênica , Proteínas de Insetos , Espécies Introduzidas , Tisanópteros , Animais , Arginina Quinase/biossíntese , Arginina Quinase/química , Arginina Quinase/genética , Proteínas de Insetos/biossíntese , Proteínas de Insetos/química , Proteínas de Insetos/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Tisanópteros/enzimologia , Tisanópteros/genética
2.
Pestic Biochem Physiol ; 114: 32-7, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25175647

RESUMO

Spinosad has been widely used in Australia to control western flower thrips Frankliniella occidentalis (Pergande) but spinosad usefulness is now compromised by resistance. Here we studied a highly spinosad resistant strain of F. occidentalis to explore if esterases had a role in spinosad resistance. Enhanced esterase activity in pressured spinosad-resistant F. occidentalis was confirmed via PAGE electrophoresis and estimated to be approximately three times higher than that in a susceptible strain. Spinosad-esterase inhibition data in the resistant strain, showed a concentration effect with significant esterase-spinosad binding occurring at spinosad concentrations from 6.2× 10(-7) to 1.5× 10(-5) M. Similarly, a spinosad-piperonyl butoxide (PBO) inhibition curve showed a concentration effect, with significant esterase-PBO binding occurring in the resistant strain at PBO concentrations between 3.3× 10(-5) M and 8.4× 10(-4) M. No binding of esterase to spinosad or PBO occurred in the susceptible strain. Results of bioassays in which spinosad resistant F. occidentalis were sprayed with a 4h delayed release formulation of cyclodextrin-complexed spinosad with immediately available PBO demonstrated that spinosad resistance was significantly reduced from 577 to 72-fold. With further development the PBO synergism of spinosad using a delayed release formulation, similar to that used here, may provide effective control for spinosad resistant F. occidentalis. Temporal synergism of spinosad may prove to be effective tactic for the control of spinosad resistant F. occidentalis where the main resistance mechanism involved has been confirmed to be esterase based.


Assuntos
Esterases/metabolismo , Inseticidas/farmacologia , Macrolídeos/farmacologia , Sinergistas de Praguicidas/farmacologia , Butóxido de Piperonila/farmacologia , Tisanópteros/enzimologia , Animais , Austrália , Combinação de Medicamentos , Feminino , Resistência a Inseticidas/fisiologia , Isoenzimas/metabolismo , Tisanópteros/efeitos dos fármacos
3.
PLoS One ; 9(7): e101791, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24992484

RESUMO

Thrips tabaci is a major pest of high-value vegetable crops and understanding its population genetics will advance our knowledge about its ecology and management. Mitochondrial cytochrome oxidase subunit I (COI) gene sequence was used as a molecular marker to analyze T. tabaci populations from onion and cabbage fields in New York. Eight COI haplotypes were identified in 565 T. tabaci individuals collected from these fields. All T. tabaci were thelytokous and genetically similar to those originating from hosts representing seven plant families spanning five continents. The most dominant haplotype was NY-HT1, accounting for 92 and 88% of the total individuals collected from onion fields in mid-summer in 2005 and 2007, respectively, and 100 and 96% of the total in early fall in 2005 and 2007, respectively. In contrast, T. tabaci collected from cabbage fields showed a dynamic change in population structure from mid-summer to early fall. In mid-summer, haplotype NY-HT2 was highly abundant, accounting for 58 and 52% of the total in 2005 and 2007, respectively, but in early fall it decreased drastically to 15 and 7% of the total in 2005 and 2007, respectively. Haplotype NY-HT1 accounted for 12 and 46% of the total in cabbage fields in mid-summer of 2005 and 2007, respectively, but became the dominant haplotype in early fall accounting for 81 and 66% of the total in 2005 and 2007, respectively. Despite the relative proximity of onion and cabbage fields in the western New York landscape, T. tabaci populations differed seasonally within each cropping system. Differences may have been attributed to better establishment of certain genotypes on specific hosts or differing colonization patterns within these cropping systems. Future studies investigating temporal changes in T. tabaci populations on their major hosts in these ecosystems are needed to better understand host-plant utilization and implications for population management.


Assuntos
Complexo IV da Cadeia de Transporte de Elétrons/genética , Proteínas de Insetos/genética , Tisanópteros/classificação , Tisanópteros/enzimologia , Animais , Brassica/parasitologia , Produtos Agrícolas/parasitologia , Haplótipos , Cebolas/parasitologia , Filogenia , Estações do Ano , Análise de Sequência de DNA , Tisanópteros/genética
4.
J Econ Entomol ; 106(1): 408-18, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23448058

RESUMO

Thrips are direct pests as well as vectors of important viruses infecting crop plants. One of the major constraints in studying the relationship between thrips vectors and tospoviruses is the difficulty of identifying the vector species because of high intraspecific variation among thrips populations. Molecular approaches have been used to identify species differences. In this study, partial cytochrome oxidase I (COI) sequences were used to understand the phylogenetic relationship among thrips populations, and assess their usefulness to identify and classify unknown thrips species collected from different crops. In total, 29 COI variants were obtained while examining the sequence polymorphisms in COI of 182 insects analyzed in this study, which were collected from six countries on tomato, chilli, onion, cabbage, cucumber, watermelon, Ethiopian mustard, French bean, and peanut. The phylogenetic analysis showed that the insects used in this study clustered with five distinct species-groups designated as Thrips palmi group, T. tabaci group, Frankliniella occidentalis group, Scirtothrips dorsalis group and an unclassified group. Higher intraspecific genetic variation was observed in S. dorsalis and T. palmi followed by T. tabaci and F. occidentalis. Thus, it was confirmed that the COI gene could be useful in grouping different thrips species and genera that coexist in a particular cropping system.


Assuntos
Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Filogenia , Tisanópteros/enzimologia , Animais , Produtos Agrícolas , Variação Genética , Herbivoria , Análise de Sequência de DNA , Tisanópteros/classificação
5.
Ying Yong Sheng Tai Xue Bao ; 23(7): 1933-9, 2012 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-23173470

RESUMO

To understand the resistance risks of Frankliniella occidentalis Pergande against phoxim, this paper studied the resistance mechanisms of phoxim-resistant F. occidentalis population against phoxim and the cross-resistance of the population against other insecticides. The phoxim-resistant population had medium level cross-resistance to chlorpyrifos, lambda-cyhalothrin, and methomyl, low level cross-resistance to chlorfenapyr, imidacloprid, emamectin-benzoate, and spinosad, but no cross-resistance to acetamiprid and abamectin. The synergists piperonyl butoxide (PBO), s, s, s-tributyl phosphorotrithioate (DEF), and triphenyl phosphate (TPP) had significant synergism (P < 0.05) on the toxicity of phoxim to the resistant (XK), field (BJ), and susceptible (S) populations, while diethyl maleate (DEM) had no significant synergism to XK and S populations but had significant synergism to BJ population. As compared with S population, the XK and BJ populations had significantly increased activities of mixed-functional oxidases P450 (2.79-fold and 1.48-fold), b, (2.88-fold and 1.88-fold), O-demethylase (2.60-fold and 1.68-fold), and carboxylesterase (2.02-fold and 1.61-fold, respectively), and XK population had a significantly increased acetylcholine esterase activity (3.10-fold). Both XK and BJ population had an increased activity of glutathione S-transferases (1.11-fold and 1.20-fold, respectively), but the increment was not significant. The increased detoxification enzymes activities in F. occidentalis could play an important role in the resistance of the plant against phoxim.


Assuntos
Resistência a Inseticidas , Inseticidas/farmacologia , Compostos Organotiofosforados/farmacologia , Tisanópteros/efeitos dos fármacos , Tisanópteros/crescimento & desenvolvimento , Acetilcolinesterase/metabolismo , Animais , Clorpirifos/farmacologia , Metomil/farmacologia , Nitrilos/farmacologia , Piretrinas/farmacologia , Tisanópteros/enzimologia
6.
J Econ Entomol ; 105(3): 1006-18, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22812142

RESUMO

Control of Frankliniella occidentalis (Pergande) is a serious problem for agriculture all over the world because of the limited range of insecticides that are available. Insecticide resistance in F. occidentalis has been reported for all major insecticide groups. Our previous studies showed that cytochrome P450-mediated detoxification is a major mechanism responsible for insecticide resistance in this pest. Degenerate polymerase chain reaction was used to identify P450 genes that might be involved in acrinathrin resistance, in a laboratory population of F. occidentalis. Associated sequences were classified as belonging to the CYP4 and CYP6 families. Real-time quantitative polymerase chain reaction analyses revealed that two genes, CYP6EB1 and CYP6EC1, were over-expressed in adults and L2 larvae of the resistant population, when compared with the susceptible population, suggesting their possible involvement in resistance to acrinathrin.


Assuntos
Sistema Enzimático do Citocromo P-450/genética , Inseticidas , Piretrinas , Tisanópteros/genética , Sequência de Aminoácidos , Animais , Expressão Gênica , Resistência a Inseticidas/genética , Larva/enzimologia , Dados de Sequência Molecular , Alinhamento de Sequência , Análise de Sequência de DNA , Tisanópteros/enzimologia
7.
Pest Manag Sci ; 67(12): 1549-56, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21656898

RESUMO

BACKGROUND: Western flower thrips (WFT), Frankliniella occidentalis (Pergande), is among the most important crop pests in the south-eastern region of Spain. Its increasing resistance to insecticides constitutes a serious problem, and understanding the mechanisms involved is therefore of great interest. Use of synergists to inhibit the enzymes involved in insecticide detoxification is widely used to determine their responsibility for insecticide resistance. However, they do not always act as intended or expected, and caution must be exercised when interpreting synergist results. RESULTS: Laboratory-selected strains of WFT were used to analyse the effects of the synergists piperonyl butoxide (PBO), S,S,S-tributyl phosphorotrithioate (DEF) and methiocarb on total esterase activity. Significant differences were found, indicating esterase activity inhibition by DEF, a lower effect for methiocarb and a small inhibition of the activity by PBO. Esterase isoenzyme inhibition by these compounds showed a similar result; this assay revealed an extreme sensitivity of Triplet A (resistance-associated esterases) to DEF. In an in vivo assay carried out with these compounds at different incubation times, only DEF caused posterior in vitro esterase activity inhibition, with a maximum effect 1 h after treatment. CONCLUSION: In this work, only DEF shows true synergistic inhibition of WFT esterases.


Assuntos
Inibidores Enzimáticos/farmacologia , Esterases/metabolismo , Sinergistas de Praguicidas/farmacologia , Tisanópteros/efeitos dos fármacos , Animais , Carbamatos/farmacologia , Ativação Enzimática , Ensaios Enzimáticos , Resistência a Inseticidas , Inseticidas/farmacologia , Isoenzimas/metabolismo , Metiocarb/farmacologia , Organotiofosfatos/farmacologia , Piretrinas/farmacologia , Tisanópteros/enzimologia , Fatores de Tempo
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