Tetranychus urticae
Koch is one of the most common and harmful pests in vegetable production areas. Similar to other countries, control of
T. urticae
is mainly based on acaricides in Turkey. However,
...T. urticae
rapidly develops resistance and failures in chemical control have occurred frequently. The toxicity of various acaricides was investigated in ten
T. urticae
populations collected from vegetable crops in Turkey. In addition, populations were screened for the presence of currently known target-site resistance mutations. It was shown that resistance to bifenthrin was the most widespread, but also half of the populations were resistant to abamectin and hexythiazox. Resistance mutations in the voltage-gated sodium channel (VGSC) and chitin synthase 1 were found in various populations. Moreover, for the first time, F1538I and L1024V VGSC mutations were reported for Turkish populations. Mutations that confer resistance to abamectin, bifenazate and METI-I acaricides such as pyridaben were not detected. These results will contribute to the design of an effective resistance management program in Turkey.
Acaricides used against
Tetranychus urticae
Koch, 1836 (Acari: Tetranychidae) in cotton fields cause control failure over time. To determine the resistance status of
T. urticae
populations to ...tebufenpyrad and bifenazate, different populations collected from Aydın (AYD), Adana (ADA), Şanlıurfa (SAN), and Diyarbakır (DIY) provinces of Türkiye, between 2019 and 2020, were subjected to diagnostic dose bioassays. Firstly, the spider mites were eliminated with a discriminating dose. Afterwards, LC
50
and LC
90
of the remaining populations were determined and the ten highest resistant populations were selected. The highest phenotypic resistance to bifenazate was observed in AYD4 and DIY2 (LC
50
57.14 mg L
− 1
with 85.01-fold and LC
50
30.15 mg L
− 1
with 44.86-fold, respectively), while the lowest phenotypic resistance was found in SAN6 (LC
50
1.5 mg L
− 1
; 2.28-fold). Considering the phenotypic resistance to tebufenpyrad, the highest resistance was found in AYD4 population (LC
50
96.81 mg L
− 1
; 12.92-fold), while the lowest - in DIY28 population (LC
50
21.23 mg L
− 1
; 2.83-fold). In pharmacokinetic studies, the ADA16 population was compared with the sensitive German Susceptible Strain population and it was determined that carboxylesterase activity was statistically higher (1.46 ± 0.04 nmol/min/mg protein enzyme activation 2.70-fold). The highest activation of glutathione
S
-transferase was detected in ADA16 (1.49 ± 0.01 nmol/min/mg protein; 2.32-fold). No mutations were found in PSST (METI 1), the point mutation site for tebufenpyrad, and Cytb (METI 3), the point mutation site for bifenazate. In terms of phenotypic resistance, bifenazate was found to be moderately resistant in two populations (85.01 and 44.86-fold), while tebufenpyrad was moderately resistant in one population (12.92-fold). This study showed that both acaricides are still effective against
T. urticae
populations.
Tetranychus urticae Koch is a serious pest of strawberries and its remarkable ability to develop resistance has often caused failure in chemical control. In the present study, resistance to ...spiromesifen was detected in two out of nine field-populations of T. urticae collected from important strawberry production areas in Turkey, with resistance ratio's mounting to 60- and 140-fold. Synergism assays showed the involvement of detoxification enzymes, especially cytochrome P450 monooxygenases, in resistance against spiromesifen in field-collected T. urticae populations. We further selected the most resistant field-collected population (POP14) with spiromesifen and obtained an extremely resistant population (LC50 > 5000 mg a.i./L). Gene expression analysis with qPCR supported the involvement of cytochrome P450s in spiromesifen resistance in this selected population. In addition, we also detected a higher expression of acetyl-CoA carboxylase (ACCase), the target-site of spiromesifen, in the spiromesifen-selected population. Furthermore, a F1640L mutation in the conserved region of CT-domain of ACCase was uncovered in the most resistant field populations, but the role of this mutation in spiromesifen resistance needs further validation. Overall, spiromesifen still seems to be an effective tool in the control of T. urticae in strawberry production areas of Turkey, but resistance is on the rise and should be considered a serious threat.
•Spiromesifen was effective against most of the sampled T. urticae populations.•Two out of nine populations showed more than 60-fold resistance to spiromesifen.•P450s play a role in spiromesifen resistance.•A target-site mutation F1640L in ACCase was uncovered.•Higher expression of ACCase could also contribute to resistance.
The poultry red mite, Dermanyssus gallinae, is the most important blood sucking ectoparasite of egg laying hens and causes economic losses in poultry farms worldwide. Although various management ...methods exist, the control of poultry red mites (PRMs) mainly relies on acaricides such as pyrethroids and organophosphates (OPs) in many regions of the world. However, repeated use of these synthetic chemicals has resulted in resistance development causing control failure of PRM. In this study, we investigated acaricide resistance mechanisms of Turkish PRM populations. First, we obtained the COI sequence from 30 PRM populations from different regions in Turkey and identified four different COI haplotypes. Toxicity assays showed that four field-collected PRM populations were highly resistant to the pyrethroid alpha-cypermethrin, with resistance ratios (RRs) varying between 100- and 400-fold, while two of these populations had a RR of more than 24-fold against the OP acaricide phoxim. Biochemical assays showed a relatively higher activity of glutathione-S-transferases and carboxyl-cholinesterases, two well-known classes of detoxification enzymes, in one of these resistant populations. In addition, we also screened for mutations in the gene encoding the voltage-gated sodium channel (vgsc) and acetylcholinesterase 1 (ace-1), the target-site of pyrethroids and OPs, respectively. In all but two PRM populations, at least one vgsc mutation was detected. A total of four target-site mutations, previously associated with pyrethroid resistance, M918T, T929I, F1534L, F1538L were found in domain II and III of the VGSC. The T929I mutation was present in the vgsc of almost all PRM populations, while the other mutations were only found at low frequency. The G119S/A mutation in ace-1, previously associated with OP resistance, was found in PRM for the first time and present in fourteen populations. Last, both alive and dead PRMs were genotyped after pesticide exposure and supported the possible role of target-site mutations, T929I and G119S, in alpha-cypermethrin and phoxim resistance, respectively. To conclude, our study provides a current overview of resistance levels and resistance mutations in Turkish PRM populations and might aid in the design of an effective resistance management program of PRM in Turkey.
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•Turkish populations have a unique COI haplotype, compared to European populations.•High level of alpha-cypermethrin resistance was detected.•Multiple known and validated vgsc resistance mutations were present at different frequencies.•The G119S/A mutation in ace was reported for the first time in PRM and present in almost half of the populations.•Genotyping of mites after pesticide exposure supported the role of T929I and G119S mutations in acaricide resistance.
The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is the most economically important mite pest in agricultural areas and chemical acaricides are widely used to control T. ...urticae populations. Cyflumetofen is a recently introduced acaricide that inhibits the mitochondrial electron transport chain at complex II (succinate dehydrogenase, SDH), which represents the most recently developed mode of action for mite control worldwide. In the present study, started upon the launch of cyflumetofen in Turkey, a five-year survey was performed to monitor cyflumetofen susceptibility in 28 T. urticae populations collected from agricultural fields across the country. The first resistance case that might cause control failure in practical field conditions was uncovered in 2019, three years after the registration of cyflumetofen. In addition, an extremely resistant population (1722-fold resistance) was also detected towards the end of 2019. Cyflumetofen resistance did not decrease in the laboratory after relaxation of selection pressure for over one year in field-collected populations, suggesting the absence of a fitness cost associated with resistance in these populations. Next to phenotypic resistance, metabolic and physiological mechanisms underlying the decreased susceptibility were also investigated. Synergism assays showed the involvement of P450 monooxygenases in cyflumetofen resistance. Downregulation of carboxylesterases as resistance mechanism, is underpinned by the fact that pre-treatment with esterase inhibitor DEF decreased cyflumetofen toxicity in field-collected strains. Furthermore, a novel H258L substitution in the subunit B of complex II was uncovered in a field population. In silico modeling of the new mutation suggested that the mutation might indeed influence toxicity to complex II inhibitors cyenopyrafen and pyflubumide, but most likely not cyflumetofen. However, further studies are needed to uncover the exact role of this mutation in resistance to this new class of complex II inhibitors.
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•Cyflumetofen resistance was monitored in Turkish T. urticae populations for five years.•More than 1700-fold resistance was detected only three years after its introduction.•P450 inhibitor PBO significantly synergized the cyflumetofen toxicity.•A H258L mutation in subunit B of SDH was uncovered.•The potential role of new mutation in resistance was studied with molecular modeling.
The Green apple aphid,
Aphis pomi
de Geer (Hemiptera: Aphididae), is one of the most common and serious insect pests of apple orchards in Turkey. This species feeds on succulent tissue of trees, ...which can lead to leaf curling, stunting, distorted tip growth, black-sooty mold, and a vector of some plant viruses. Growers prefer to apply insecticide applications heavily to control the green apple aphid in commercial apple orchards. However, there have not been conducted any research study on insecticide resistance of
A
.
pomi
in Turkey. The resistance status of
A. pomi
populations collected from commercially apple orchards in the Central Anatolia region was investigated to: acetamiprid (neonicotinoid), the specific aphicide pirimicarb (carbamate), beta-cyfluthrin (synthetic pyrethroid), and chlorpyrifos-ethyl (organophosphate) insecticides. All populations were characterised for the first time using polyacrylamide gel electrophoresis to determine the esterase banding patterns. Biochemical assays revealed higher activity of total esterase. This is the first study conducted to determine glutathione S-transferase activity related to the insecticide resistance of
A. pomi
. It was determined that the resistance levels reached to 14.93 fold to acetamiprid, 3.74 fold to beta-cyfluthrin, 4.19 fold to chlorpyrifos-ethyl, and 4.33 fold to pirimicarb. The present study revealed neonicotinoid, organophosphate, carbamate, and pyrethroid resistance in
A. pomi
populations from the Central Anatolia Regions of Turkey. It also clearly showed that the enhanced esterase enzyme activity is the main resistance mechanism against carbamate pirimicarb resistance. The present study is the first insecticide resistance study on
A. pomi
for Turkey.
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