Tsagkarakou A

References (11)

Title : Multiple TaqMan qPCR and droplet digital PCR (ddPCR) diagnostics for pesticide resistance monitoring and management, in the major agricultural pest Tetranychus urticae - Mavridis_2022_Pest.Manag.Sci_78_263
Author(s) : Mavridis K , Papapostolou KM , Riga M , Ilias A , Michaelidou K , Bass C , Van Leeuwen T , Tsagkarakou A , Vontas J
Ref : Pest Manag Sci , 78 :263 , 2022
Abstract : BACKGROUND: Decisions on which pesticide to use in agriculture are expected to become more difficult, as the number of available chemicals is decreasing. For Tetranychus urticae (T. urticae), a major pest for which a number of candidate markers for pesticide resistance are in place, molecular diagnostics could support decision-making for the rational use of acaricides. RESULTS: A suite of 12 TaqMan qPCR assays [G314D (GluCl1), G326E, I321T (GluCl3), G119S, F331W (Ace-1), H92R (PSST), L1024V, F1538I (VGSC), I1017F (CHS1), G126S, S141F, P262T (cytb)], were validated against Sanger-sequencing, and subsequently adapted for use with the ddPCR technology. The concordance correlation coefficient between the actual and ddPCR measured mutant allelic frequencies was 0.995 (95% CI = 0.991-0.998), and no systematic, proportional, or random differences were detected. The achieved Limit of Detection (LoD) was 0.1% (detection of one mutant in a background of 999 wild type mites). The ddPCR assay panel was then assessed in terms of agreement with phenotypic resistance, through a pilot application in field populations from Crete, with strong correlation and thus predictive and diagnostic value of the molecular assays in some cases (e.g., etoxazole and abamectin resistance). Molecular diagnostics were able to capture incipient resistance that was otherwise missed by phenotypic bioassays. The molecular and phenotypic resistance screening of T. urticae field populations from Crete, revealed both multi-resistant and susceptible populations. CONCLUSION: The highly sensitive T. urticae molecular diagnostic platforms developed in this study could prove a valuable tool for pesticide resistance management.
ESTHER : Mavridis_2022_Pest.Manag.Sci_78_263
PubMedSearch : Mavridis_2022_Pest.Manag.Sci_78_263
PubMedID: 34480408

Title : Next-generation molecular diagnostics (TaqMan qPCR and ddPCR) for monitoring insecticide resistance in Bemisia tabaci - Mavridis_2022_Pest.Manag.Sci__
Author(s) : Mavridis K , Papapostolou KM , Ilias A , Michaelidou K , Stavrakaki M , Roditakis E , Tsagkarakou A , Bass C , Vontas J
Ref : Pest Manag Sci , : , 2022
Abstract : BACKGROUND: Insecticide resistance has developed in several populations of the whitefly Bemisia tabaci worldwide and threatens to compromise the efficacy of chemical control. The molecular mechanisms underpinning resistance have been characterized and markers associated with the trait have been identified, allowing the development of diagnostics for individual insects. RESULTS: TaqMan and Droplet Digital PCR (ddPCR) assays were developed and validated, in individual and pooled whitefly samples, respectively, for the following target-site mutations: the acetylcholinesterase (ace1) F331W mutation conferring organophosphate-resistance; the voltage-gated sodium channel (vgsc) mutations L925I and T929V conferring pyrethroid-resistance; and the acetyl-CoA carboxylase (acc) A2083V mutation conferring ketoenol-resistance. The ddPCR's limit of detection (LoD) was <0.2% (i.e. detection of one heterozygote whitefly in a pool of 249 wild-type individuals). The assays were applied in 11 B. tabaci field populations from four locations in Crete, Greece. The F331W mutation was detected to be fixed or close to fixation in eight of 11 B. tabaci populations, and at lower frequency in the remaining ones. The pyrethroid-resistance mutations were detected at very high frequencies. The A2083V spiromesifen resistance mutation was detected in eight of 11 populations (frequencies = 6.16-89.56%). Spiromesifen phenotypic resistance monitoring showed that the populations tested had variable levels of resistance, ranging from full susceptibility to high resistance. A strong spiromesifen-resistance phenotype-genotype (A2083V) correlation (r(s) = -0.839, P = 0.002) was observed confirming the ddPCR diagnostic value. CONCLUSION: The ddPCR diagnostics developed in this study are a valuable tool to support evidence-based rational use of insecticides and resistance management strategies. 2022 Society of Chemical Industry.
ESTHER : Mavridis_2022_Pest.Manag.Sci__
PubMedSearch : Mavridis_2022_Pest.Manag.Sci__
PubMedID: 36054028

Title : Ryanodine receptor point mutations confer diamide insecticide resistance in tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae) - Roditakis_2017_Insect.Biochem.Mol.Biol_80_11
Author(s) : Roditakis E , Steinbach D , Moritz G , Vasakis E , Stavrakaki M , Ilias A , Garcia-Vidal L , Martinez-Aguirre MD , Bielza P , Morou E , Silva JE , Silva WM , Siqueira Eta A , Iqbal S , Troczka BJ , Williamson MS , Bass C , Tsagkarakou A , Vontas J , Nauen R
Ref : Insect Biochemistry & Molecular Biology , 80 :11 , 2017
Abstract : Insect ryanodine receptors (RyR) are the molecular target-site for the recently introduced diamide insecticides. Diamides are particularly active on Lepidoptera pests, including tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae). High levels of diamide resistance were recently described in some European populations of T. absoluta, however, the mechanisms of resistance remained unknown. In this study the molecular basis of diamide resistance was investigated in a diamide resistant strain from Italy (IT-GELA-SD4), and additional resistant field populations collected in Greece, Spain and Brazil. The genetics of resistance was investigated by reciprocally crossing strain IT-GELA-SD4 with a susceptible strain and revealed an autosomal incompletely recessive mode of inheritance. To investigate the possible role of target-site mutations as known from diamondback moth (Plutella xylostella), we sequenced respective domains of the RyR gene of T. absoluta. Genotyping of individuals of IT-GELA-SD4 and field-collected strains showing different levels of diamide resistance revealed the presence of G4903E and I4746M RyR target-site mutations. These amino acid substitutions correspond to those recently described for diamide resistant diamondback moth, i.e. G4946E and I4790M. We also detected two novel mutations, G4903V and I4746T, in some of the resistant T. absoluta strains. Radioligand binding studies with thoracic membrane preparations of the IT-GELA-SD4 strain provided functional evidence that these mutations alter the affinity of the RyR to diamides. In combination with previous work on P. xylostella our study highlights the importance of position G4903 (G4946 in P. xylostella) of the insect RyR in defining sensitivity to diamides. The discovery of diamide resistance mutations in T. absoluta populations of diverse geographic origin has serious implications for the efficacy of diamides under applied conditions. The implementation of appropriate resistance management strategies is strongly advised to delay the further spread of resistance.
ESTHER : Roditakis_2017_Insect.Biochem.Mol.Biol_80_11
PubMedSearch : Roditakis_2017_Insect.Biochem.Mol.Biol_80_11
PubMedID: 27845250

Title : The tomato borer, Tuta absoluta, invading the Mediterranean Basin, originates from a single introduction from Central Chile - Guillemaud_2015_Sci.Rep_5_8371
Author(s) : Guillemaud T , Blin A , Le Goff I , Desneux N , Reyes M , Tabone E , Tsagkarakou A , Nino L , Lombaert E
Ref : Sci Rep , 5 :8371 , 2015
Abstract : The Lepidopteran pest of tomato, Tuta absoluta, is native to South America and is invasive in the Mediterranean basin. The species' routes of invasion were investigated. The genetic variability of samples collected in South America, Europe, Africa and Middle East was analyzed using microsatellite markers to infer precisely the source of the invasive populations and to test the hypothesis of a single versus multiple introductions into the old world continents. This analysis provides strong evidence that the origin of the invading populations was unique and was close to or in Chile, and probably in Central Chile near the town of Talca in the district of Maule.
ESTHER : Guillemaud_2015_Sci.Rep_5_8371
PubMedSearch : Guillemaud_2015_Sci.Rep_5_8371
PubMedID: 25667134

Title : Global distribution and origin of target site insecticide resistance mutations in Tetranychus urticae - Ilias_2014_Insect.Biochem.Mol.Biol_48_17
Author(s) : Ilias A , Vontas J , Tsagkarakou A
Ref : Insect Biochemistry & Molecular Biology , 48 :17 , 2014
Abstract : The control of Tetranychus urticae, a worldwide agricultural pest, is largely dependent on pesticides. However, their efficacy is often compromised by the development of resistance. Recent molecular studies identified a number of target site resistance mutations, such as G119S, A201S, T280A, G328A, F331W in the acetylcholinesterase gene, L1024V, A1215D, F1538I in the voltage-gated sodium channel gene, G314D and G326E in glutamate-gated chloride channel genes, G126S, I136T, S141F, D161G, P262T in the cytochrome b and the I1017F in the chitin synthase 1 gene. We examined their distribution, by sequencing the relevant gene fragments in a large number of T. urticae collections from a wide geographic range. Our study revealed that most of the resistance mutations are spread worldwide, with remarkably variable frequencies. Furthermore, we analyzed the variability of the ace locus, which has been subjected to longer periods of selection pressure historically, to investigate the evolutionary origin of ace resistant alleles and determine whether they resulted from single or multiple mutation events. By sequencing a 1540 bp ace fragment, encompassing the resistance mutations and downstream introns in 139 T. urticae individuals from 27 countries, we identified 6 susceptible and 31 resistant alleles which have arisen from at least three independent mutation events. The frequency and distribution of these ace haplotypes varied geographically, suggesting an interplay between different mutational events, gene flow and local selection.
ESTHER : Ilias_2014_Insect.Biochem.Mol.Biol_48_17
PubMedSearch : Ilias_2014_Insect.Biochem.Mol.Biol_48_17
PubMedID: 24602758
Gene_locus related to this paper: tetur-ACHE

Title : Acetylcholinesterase point mutations in European strains of Tetranychus urticae (Acari: Tetranychidae) resistant to organophosphates - Khajehali_2010_Pest.Manag.Sci_66_220
Author(s) : Khajehali J , Van Leeuwen T , Grispou M , Morou E , Alout H , Weill M , Tirry L , Vontas J , Tsagkarakou A
Ref : Pest Manag Sci , 66 :220 , 2010
Abstract : BACKGROUND: In Tetranychus urticae Koch, acetylcholinesterase insensitivity is often involved in organophosphate (OP) and carbamate (CARB) resistance. By combining toxicological, biochemical and molecular data from three reference laboratory and three OP selected strains (OP strains), the AChE1 mutations associated with resistance in T. urticae were characterised. RESULTS: The resistance ratios of the OP strains varied from 9 to 43 for pirimiphos-methyl, from 78 to 586 for chlorpyrifos, from 8 to 333 for methomyl and from 137 to 4164 for dimethoate. The insecticide concentration needed to inhibit 50% of the AChE1 activity was, in the OP strains, at least 2.7, 55, 58 and 31 times higher for the OP pirimiphos-methyl, chlorpyrifos oxon, paraoxon and omethoate respectively, and 87 times higher for the CARB carbaryl. By comparing the AChE1 sequence, four amino acid substitutions were detected in the OP strains: (1) F331W (Torpedo numbering) in all the three OP strains; (2) T280A found in the three OP strains but not in all clones; (3) G328A, found in two OP strains; (4) A201S found in only one OP strain. CONCLUSIONS: Four AChE1 mutations were found in resistant strains of T. urticae, and three of them, F331W, G328A and A201S, are possibly involved in resistance to OP and CARB insecticides. Among them, F331W is probably the most important and the most common in T. urticae. It can be easily detected by the diagnostic PCR-RLFP assay developed in this study.
ESTHER : Khajehali_2010_Pest.Manag.Sci_66_220
PubMedSearch : Khajehali_2010_Pest.Manag.Sci_66_220
PubMedID: 19894225
Gene_locus related to this paper: tetur-ACHE

Title : Acaricide resistance mechanisms in the two-spotted spider mite Tetranychus urticae and other important Acari: a review - Van Leeuwen_2010_Insect.Biochem.Mol.Biol_40_563
Author(s) : Van Leeuwen T , Vontas J , Tsagkarakou A , Dermauw W , Tirry L
Ref : Insect Biochemistry & Molecular Biology , 40 :563 , 2010
Abstract : The two-spotted spider mite Tetranychus urticae Koch is one of the economically most important pests in a wide range of outdoor and protected crops worldwide. Its control has been and still is largely based on the use of insecticides and acaricides. However, due to its short life cycle, abundant progeny and arrhenotokous reproduction, it is able to develop resistance to these compounds very rapidly. As a consequence, it has the dubious reputation to be the"most resistant species" in terms of the total number of pesticides to which populations have become resistant, and its control has become problematic in many areas worldwide. Insecticide and acaricide resistance has also been reported in the ectoparasite Sarcoptes scabiei, the causative organism of scabies, and other economically important Acari, such as the Southern cattle tick Rhipicephalus microplus, one of the biggest arthropod threats to livestock, and the parasitic mite Varroa destructor, a major economic burden for beekeepers worldwide. Although resistance research in Acari has not kept pace with that in insects, a number of studies on the molecular mechanisms responsible for the resistant phenotype has been conducted recently. In this review, state-of-the-art information on T. urticae resistance, supplemented with data on other important Acari has been brought together. Considerable attention is given to the underlying resistance mechanisms that have been elucidated at the molecular level. The incidence of bifenazate resistance in T. urticae is expanded as an insecticide resistance evolutionary paradigm in arthropods.
ESTHER : Van Leeuwen_2010_Insect.Biochem.Mol.Biol_40_563
PubMedSearch : Van Leeuwen_2010_Insect.Biochem.Mol.Biol_40_563
PubMedID: 20685616

Title : Current status of insecticide resistance in Q biotype Bemisia tabaci populations from Crete - Roditakis_2009_Pest.Manag.Sci_65_313
Author(s) : Roditakis E , Grispou M , Morou E , Kristoffersen JB , Roditakis N , Nauen R , Vontas J , Tsagkarakou A
Ref : Pest Manag Sci , 65 :313 , 2009
Abstract : BACKGROUND: A major problem of crop protection in Crete, Greece, is the control of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) with chemical insecticides owing to the rapid development of resistance. The aim of this study was to investigate the establishment of resistance and the underlying mechanisms to major insecticide classes with classical bioassays and known biochemical resistance markers. RESULTS: During a 2005-2007 survey, 53 Q biotype populations were collected. Application history records showed extensive use of neonicotinoids, organophosphates, carbamates and pyrethroids. High resistance levels were identified in the majority of populations (>80%) for imidacloprid (RF: 38-1958x) and alpha-cypermethrin (RF: 30-600x). Low resistance levels (RF < 12) were observed for pirimiphos-methyl. A strong correlation between resistance to imidacloprid and the number of applications with neonicotinoids was observed. Significant correlations were observed between COE and P450-dependent monoxygenase activity with resistance to alpha-cypermethrin and imidacloprid respectively. A propoxur-based AChE diagnostic test indicated that iAChE was widespread in most populations. Resistance levels for alpha-cypermethrin were increased when compared with a previous survey (2002-2003). Differentiation of LC(50) values between localities was observed for imidacloprid only. CONCLUSION: Bemisia tabaci resistance evolved differently in each of the three insecticides studied. Imidacloprid resistance seems less established and less persistent than alpha-cypermethrin resistance. The low resistance levels for pirimiphos-methyl suggest absence of cross-resistance with other organophosphates or carbamates used.
ESTHER : Roditakis_2009_Pest.Manag.Sci_65_313
PubMedSearch : Roditakis_2009_Pest.Manag.Sci_65_313
PubMedID: 19115232

Title : Molecular diagnostics for detecting pyrethroid and organophosphate resistance mutations in the Q biotype of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) - Tsagkarakou_2010_Pestic.Biochem.Physiol_94_49
Author(s) : Tsagkarakou A , Nikou Dimitra , Roditakis E , Sharvit M , Morin S , Vontas J
Ref : Pesticide Biochemistry and Physiology , 94 :49 , 2009
Abstract : Pyrethroid and organophosphate resistance-associated mutations have been recently reported in the whitefly Bemisia tabaci (Gennadius), a major pest of protected and outdoor crops worldwide. Here, we developed simple PCR-agarose gel visualization based assays for reliably monitoring the L925I and T929V pyrethroid resistance mutations in the B. tabaci para-type voltage gated sodium channel and the iAChE F331W organophosphate resistance mutation in the acetylcholinesterase enzyme ace1. PCR-RFLP assays were developed for detecting the L925I and the F331W resistance mutations. A highly specific PASA was developed for detecting the T929V mutation. The molecular diagnostic tools were used to monitor the frequency of the resistance mutations in a large number of field caught Q biotype B. tabaci from Crete (Greece), where both organophosphates and pyrethroids are extensively used. The F331W mutation was fixed in all field individuals examined. The pyrethroid resistance mutations were detected in high frequencies: 0.38 and 0.54 for L925I and T929V, respectively. The simple diagnostics are accurate and robust, to be used alongside classical bioassays to prevent ineffective insecticide applications, and for early identification of the spreading of resistant Q biotype populations into new regions around the globe.
ESTHER : Tsagkarakou_2010_Pestic.Biochem.Physiol_94_49
PubMedSearch : Tsagkarakou_2010_Pestic.Biochem.Physiol_94_49
Gene_locus related to this paper: bemta-ACHE1

Title : Insecticide resistance in Bemisia tabaci (Homoptera: Aleyrodidae) populations from Crete - Roditakis_2005_Pest.Manag.Sci_61_577
Author(s) : Roditakis E , Roditakis NE , Tsagkarakou A
Ref : Pest Manag Sci , 61 :577 , 2005
Abstract : The resistance levels to alpha-cypermethrin, bifenthrin, pirimiphos-methyl, endosulfan and imidacloprid were determined in Bemisia tabaci (Gennadius) from Crete. Five B tabaci populations collected from greenhouse and outdoor crops were bioassayed and compared with a reference susceptible strain. Bemisia tabaci collected in a floriculture greenhouse exhibited the highest resistance against all insecticides: at LC50, resistance factors were 23-fold for bifenthrin, 80-fold for alpha-cypermethrin, 18-fold for pirimiphos-methyl, 58-fold for endosulfan and 730-fold for imidacloprid. A population collected on outdoor melons was more susceptible than the reference strain against all insecticides tested, suggesting the occurrence of local highly susceptible B tabaci populations in 'refugia'. In pairwise comparisons of resistance levels, correlation was observed between the LC50 values of the pyrethroid insecticides bifenthrin and alpha-cypermethrin.
ESTHER : Roditakis_2005_Pest.Manag.Sci_61_577
PubMedSearch : Roditakis_2005_Pest.Manag.Sci_61_577
PubMedID: 15712366

Title : Mechanisms of resistance to organophosphates in Tetranychus urticae (Acari: Tetranychidae) from Greece - Tsagkarakou_2002_Insect.Biochem.Mol.Biol_32_417
Author(s) : Tsagkarakou A , Pasteur N , Cuany A , Chevillon C , Navajas M
Ref : Insect Biochemistry & Molecular Biology , 32 :417 , 2002
Abstract : We investigated the mechanisms conferring resistance to methyl-parathion (44-fold) and to methomyl (8-fold) in Tetranychus urticae from Greece by studying the effect of synergists on the resistance and the kinetic characteristics of various enzymes in a resistant strain (RLAB) and a susceptible reference strain (SAMB). It is shown that S,S,S-tributyl phosphorotrithioate, a synergist that inhibits esterases and glutathione S-transferases, and piperonyl butoxide, a synergist that inhibits cytochrome P450 mediated monooxygenases, did not affect the level of methyl-parathion or methomyl resistance in RLAB and that resistance ratios to both insecticides did not change significantly in the presence of either synergist. Isoelectric focusing of esterase allozymes on single mites revealed no differences in staining intensity and glutathione S-transferase activity was not significantly different in the two strains. The activity of two cytochrome P450 monooxygenase groups was compared. No significant difference of 7-ethoxyresorufin-O-diethylase activity was observed between strains that were two-fold higher in RLAB than in SAMB. The kinetic characteristics of acetylcholinesterase, the target enzyme of organophosphates and carbamates, revealed that acetylcholinesterase in RLAB was less sensitive to inhibition by paraoxon and methomyl in comparison with SAMB. I(50), the inhibitor concentration inducing 50% decrease of acetylcholinesterase activity was greater (119- and 50-fold with paraoxon and methomyl, respectively) and the bimolecular constant k(i) was lower (39- and 47-fold with paraoxon and methomyl, respectively) in RLAB compared to SAMB.
ESTHER : Tsagkarakou_2002_Insect.Biochem.Mol.Biol_32_417
PubMedSearch : Tsagkarakou_2002_Insect.Biochem.Mol.Biol_32_417
PubMedID: 11886776