Field-simulator studies of insecticide resistance to dimethylcarbamates and pyrethroids conferred by metabolic- and target site-based mechanisms in peach-potato aphids,Myzus persicae (Hemiptera: Aphididae)

A range of insecticides was applied at recommended application rates against populations of Myzus persicae (Sulzer) carrying various combinations of three insecticide resistance mechanisms (carboxylesterase-based metabolic resistance and two target-site mechanisms, known as MACE and kdr), supported on either Chinese cabbage or potatoes in field simulator cages. Patterns of response were similar on both host species. MACE conferred extreme resistance to pirimicarb and triazamate (dimethylcarbamate insecticides). The kdr mechanism was associated with resistance to lambda-cyhalothrin, cypermethrin and deltamethrin (pyrethroid insecticides). A mixture of pirimicarb plus lambda-cyhalothrin was only effective against M persicae not carrying kdr or carrying kdr and low carboxylesterase-based resistance. None of the insecticides tested was effective against M persicae carrying both MACE and kdr resistance. The implications of these findings for the formulation of control strategies, based on regular monitoring of resistance genotype frequencies, are discussed.     

Bioassay and field-simulator studies of the efficacy of pymetrozine against peach-potato aphids,Myzus persicae (Hemiptera: Aphididae), possessing different mechanisms of insecticide resistance

Twenty-one clones of the peach-potato aphid, Myzus persicae (Sulzer), carrying various combinations of known mechanisms of insecticide resistance were assessed for their response to the new pyridine azomethine compound, pymetrozine, in leaf-dip bioassays. Pymetrozine was also applied as a foliar spray to populations of four different UK M persicae clones on potato plants in field-simulator chambers. Neither study showed any evidence of cross-resistance to this compound. Pymetrozine, used in conjunction with other effective aphicides, such as pirimicarb and imidacloprid, can therefore play an important role in insecticide resistance-management strategies for M persicae.     

Molecular studies of knockdown resistance to pyrethroids: cloning of domain II sodium channel gene sequences from insects

Knockdown resistance (kdr) is a target-site resistance mechanism that confers nerve insensitivity to DDT and pyrethroid insecticides. In the housefly, Musca domestica, molecular cloning of the para-type sodium channel gene has revealed two amino acid mutations that are associated with kdr and super-kdr resistance phenotypes. Both mutations are located in the domain II region of the channel; Leu1014 to Phe in the hydrophobic segment IIS6 and Met918 to Thr in the IIS4-IIS5 linker. To investigate whether these mutations also occur in other insects, we have designed degenerate primers based on conserved sequences in the domain II region of the sodium channel and used these to PCR amplify this region from insecticide-susceptible strains of eight diverse insect species representing four different insect Orders: Helicoverpa armigera, Plutella xylostella, Spodoptera littoralis (Lepidoptera), Blattella germanica (Dictyoptera), Tribolium castaneum (Coleoptera), Myzus persicae, Aphis gossypii and Phorodon humuli (Hemiptera). The primers amplified closely related para-type sodium channel sequences from each insect with a minimum of 85% amino acid identity between species. All of the sequences contained ‘susceptible’ Leu and Met residues at the positions associated with kdr and super-kdr resistance in the housefly. Recent results detailing the presence of a kdr-type Leu to Phe mutation in pyrethroid-resistant strains of two important agricultural pests, P. xylostella and M. persicae, are discussed. ©1997 SCI     

The sodium channel gene in Tetranychus cinnabarinus (Boisduval): identification and expression analysis of a mutation associated with pyrethroid resistance

BACKGROUND: The carmine spider mite (CSM), Tetranychus cinnabarinus, is the most harmful mite pest of various crops and vegetable plants. Pyrethroid insecticide fenpropathrin has been used to control insects and mites worldwide, but CSM has developed resistance to this compound. RESULTS: Three synergists together eliminated about 50% resistance against fenpropathrin in the CSM. A point mutation was identified from the sodium channel gene of fenpropathrin‐resistant CSM (FeR) by comparing cDNA sequences between FeR and susceptible (S) sodium channel genes, which caused a phenylalanine (F) to isoleucine (I) change at amino acid 1538 position in IIIS6 of the sodium channel and has been proven to confer strong resistance to pyrethroid in other species. The mRNA expression of the sodium channel gene in the FeR and abamectin‐resistant strain (AbR), which was included as a control, were both relatively lower than in the S. CONCLUSION: These results demonstrate that a mutation (F1538I) is present in the sodium channel gene in FeR of CSM, likely playing an important role in fenpropathrin resistance in T. cinnabarinus, but that decrease in the abundance of sodium channel did not confer this resistance. The F1538I mutation could be used as a molecular marker for detecting kdr resistance in Arachnida populations. Copyright © 2011 Society of Chemical Industry     

Use of the RFLP-PCR diagnostic test for characterizing MACE and kdr insecticide resistance in the peach potato aphid Myzus persicae

The peach-potato aphid Myzus persicae (Sulzer) has developed a number of insecticide resistance mechanisms owing to the high selective pressure produced by world-wide insecticide treatments. Knowledge of the geographical distribution and the temporal evolution of these resistant phenotypes helps to develop suitable pest-management programs. Current understanding of the major mechanisms of resistance at the molecular level makes it possible to diagnose the presence of modified acetylcholinesterase (MACE) or knockdown resistance (kdr). This paper describes a rapid method for the identification of both resistance mechanisms in a single molecular assay by using restriction fragment length polymorphism of PCR products (RFLP-PCR) in individual as well as pooled aphids.     

Insecticide resistance compromises the control of Aedes aegypti in Bangladesh

BACKGROUND

With no effective drugs or widely available vaccines, dengue control in Bangladesh is dependent on targeting the primary vector Aedes aegypti with insecticides and larval source management. Despite these interventions, the dengue burden is increasing in Bangladesh, and the country experienced its worst outbreak in 2019 with 101 354 hospitalized cases. This may be partially facilitated by the presence of intense insecticide resistance in vector populations. Here, we describe the intensity and mechanisms of resistance to insecticides commonly deployed against Ae. aegypti in Dhaka, Bangladesh.

RESULTS

Dhaka Ae. aegypti colonies exhibited high-intensity resistance to pyrethroids. Using CDC bottle assays, we recorded 2–24% mortality (recorded at 24 h) to permethrin and 48–94% mortality to deltamethrin, at 10× the diagnostic dose. Bioassays conducted using insecticide–synergist combinations suggested that metabolic mechanisms were contributing to pyrethroid resistance, specifically multi-function oxidases, esterases, and glutathione S-transferases. In addition, kdr alleles were detected, with a high frequency (78–98%) of homozygotes for the V1016G mutation. A large proportion (≤ 74%) of free-flying and resting mosquitoes from Dhaka colonies survived exposure to standard applications of pyrethroid aerosols in an experimental free-flight room. Although that exposure affected the immediate host-seeking behavior of Ae. aegypti, the effect was transient in surviving mosquitoes.

CONCLUSION

The intense resistance characterized in this study is likely compromising the operational effectiveness of pyrethroids against Ae. aegypti in Dhaka. Switching to alternative chemical classes may offer a medium-term solution, but ultimately a more sustainable and effective approach to controlling dengue vectors is required. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

The Pyrethrins and Related Compounds. Part XLI. Structure–Activity Relationships in Non-ester Pyrethroids against Resistant Strains of Housefly (Musca domestica L.)

A series of pyrethroids, related to NRDC 200 and etofenprox (MTI500) in which the central region is represented by a non-ester link, have been tested against one susceptible and two resistant strains (kdr and super-kdr) of houseflies (Musca domestica L.). A range of structural variations in the central region have been examined. Resistance factors mostly fell within narrow ranges for both resistant strains i.e. 10–50-fold resistance against kdr and 50–150-fold against super-kdr; thus no correlation of resistance with structural features was detectable for this region. Other changes examined were the substituent on the phenyl ring in the ‘acid’ component and the bridging group in the ‘alcohol’ component where small variations in response were observed. Examination of the effect of varying the ‘alcohol’ side chain was limited by lack of active analogues.     

Frequency and intensity of pyrethroid resistance through the CDC bottle bioassay and their association with the frequency of kdr mutations in Aedes aegypti (Diptera: Culicidae) from Mexico

BACKGROUND

The control of Aedes aegypti (L.), the main urban vector that causes arboviral diseases such as dengue, Chikungunya and Zika, has proved to be a challenge because of a rapid increase in insecticide resistance. Therefore, adequate monitoring of insecticide resistance is an essential element in the control of Ae. aegypti and the diseases it transmits. We estimated the frequency and intensity (Resistance Frequency Rapid Diagnostic Test [F‐RDT] and Resistance Intensity Rapid Diagnostic Test [I‐RDT]) of pyrethroid resistance in populations of Ae. aegypti from Mexico using the bottle bioassay and results were related to the frequencies of knockdown resistance (kdr) mutations V1016I and F1534C.

RESULTS

All populations under study were resistant to the pyrethroids: bifenthrin (99%), d‐(cis–trans)‐phenothrin (6.3% cis, 91.7% trans) and permethrin (99.5%) according to F‐RDT, and showed moderate to high‐intensity resistance at 10× the diagnostic dose (DD) in I‐RDT. Frequencies of the kdr mutation V1016I in Ae. aegypti populations were correlated with moderate permethrin resistance at 10× DD, whereas F1534C mutation frequencies were correlated with high bifenthrin resistance at 5× DD. Both I1016 and C1535 were highly correlated with high‐intensity phenothrin resistance at 1× to 10× DD.

CONCLUSIONS

This study showed that high frequencies of kdr mutations V1016I and F1534C are reflected in the results of F‐RDT and I‐RDT tests. Bioassays in conjunction with the characterization of genetic resistance mechanisms are indispensable in the strategic and rational management of resistance in mosquitoes. © 2018 Society of Chemical Industry

     

Involvement of a sodium channel mutation in pyrethroid resistance in Cydia pomonella L, and development of a diagnostic test

Populations of the codling moth, Cydia pomonella L (Lepidoptera, Tortricidae) have developed resistance to several classes of insecticide such as benzoylureas, juvenile hormone analogues, ecdysone agonists and pyrethroids, but the corresponding resistance mechanisms have not been extensively studied. Knockdown resistance (kdr) to pyrethroid insecticides has been associated with point mutations in the para sodium channel gene in a great variety of insect pest species. We have studied two susceptible strains (S and Sv) and two resistant strains (Rt and Rv) of C pomonella that exhibited 4- and 80-fold resistance ratios to deltamethrin, respectively. The region of the voltage-dependent sodium channel gene which includes the position where kdr and super-kdr mutations have been found in Musca domestica L was amplified. The kdr mutation, a leucine-to-phenylalanine replacement at position 1014, was found only in the Rv strain. In contrast, the super-kdr mutation, a methionine-to-threonine replacement at position 918, was not detected in any C pomonella strain. These data allowed us to develop a PCR-based diagnostic test (PASA) to monitor the frequency of the kdr mutation in natural populations of C pomonella in order to define appropriate insecticide treatments in orchards.     

The pyrethrins and related compounds part XXXIX— structure-activity relationships of pyrethroidal esters with cyclic side chains in the alcohol component against resistant strains of housefly (Musca domestica)

Activities of a range of pyrethroidal esters, incorporating structural variations in all regions of the acid and alcohol components, have been measured against two fully characterised and homozygous resistant strains of Musca domestica L. (kdr and super-kdr). The results, limited in this paper to esters of alcohols with cyclic side chains, indicate uniform resistance to the kdr strain across the whole range of structural variations. Against the super-kdr strain, while variation in the acid component has little effect, the resistance factor is sensitive to the nature of the alcohol component, in particular on whether it contains an α-cyano substituent.     

The pyrethrins and related compounds part XL— structure-activity relationships of pyrethroidal esters with acyclic side chains in the alcohol component against resistant strains of housefly (Musca domestica)

Activities of a range of pyrethroidal esters, incorporating structural variations in all regions of the acid and alcohol components, have been measured against two fully characterised and homozygous resistant strains of Musca domestica (kdr and super-kdr). The results, limited in this paper to esters of alcohols with acyclic side chains, show the same level of uniform resistance as the kdr strain observed previously, across a range of acid and alcohol variations. Against the super-kdr strain, in contrast to the cyclic side chain set, resistance factors are barely higher than for the kdr strain. Against super-kdr flies, some dependence of resistance factor on the position of the side chain substituent was detected. Polyfluorobenzyl esters confer particularly low resistance factors.     

Field-simulator study of insecticide resistance conferred by esterase-, MACE- and kdr-based mechanisms in the peach-potato aphid,Myzus persicae (Sulzer)

Insecticide sprays were applied to Myzus persicae (Sulzer) populations carrying various combinations of three insecticide resistance mechanisms (esterase-based metabolic resistance and two target site mechanisms, known as MACE and kdr), supported on host plants growing in field simulator cages. The study showed that MACE confers extreme resistance to pirimicarb and triazamate (carbamate insecticides) but not to deltamethrin + heptenophos (16 + 1) (Decisquick) or dimethoate (an organophosphorus insecticide). Resistance to dimethoate depends solely on levels of esterase-based resistance, while resistance to Decisquick depends on kdr and esterase. None of the four insecticides is effective against aphids carrying MACE combined with extreme esterase-based resistance. This knowledge, in association with current monitoring of the mechanisms, will play an important role in making decisions on insecticide use against M persicae in the UK. © 1999 Society of Chemical Industry