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Background: The green peach aphid, Myzus persicae (Sulzer), is one of the most economically important crop pests worldwide. Insecticide resistance in this pest was first detected over 60 years ago, with resistance in M. persicae now spanning over 80 active ingredients. Sulfoxaflor is a relatively new insecticide that is primarily used to control sap-feeding insects. In 2018 resistance to sulfoxaflor was discovered in field populations of M. persicae in Australia. This study aimed to determine the current distribution and phenotypic levels of sulfoxaflor resistance in Australian clones of M. persicae and to investigate how these patterns relate to clonal type., Results: For the first time, we show there is low-level resistance (8-26-fold) distributed across Australia, with resistance being detected in aphids collected from approximately 20% of all M. persicae collected and screened. Furthermore, this study shows sulfoxaflor resistance is found in two M. persicae haplotypes, providing evidence that there have been multiple independent evolutionary events which have given rise to sulfoxaflor resistance in this species., Conclusion: These findings have important implications for the chemical control of M. persicae in Australia, especially when considering the broader genetic background of these aphids which are known to harbour a number of other insecticide resistance mechanisms. We recommend continuous monitoring of sulfoxaflor resistance in field populations of M. persicae (in Australia and elsewhere) and further research into the underlying genetic mechanisms conferring resistance to sulfoxaflor in both clonal haplotypes. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

Background: Dusky cotton bug (DCB), Oxycarenus hyalinipennis (Costa) (Hemiptera: Lygaeidae), is a key insect pest of cotton. It causes huge losses to cotton and many other economically important crops. Sulfoxaflor is a newly introduced systemic insecticide that is effective against many sap-feeding insect pests such as aphids, whiteflies and true bugs. The present study was designed to characterize the inheritance of sulfoxaflor resistance in DCB. Moreover, the role of synergists in reducing sulfoxaflor resistance in DCB was also assessed., Results: A field population of DCB has developed 1132.0-fold resistance to sulfoxaflor after 11 selected generations in the laboratory. Nonsignificant difference of reciprocal crosses was observed depending on the LC 50 (median lethal concentration) values (95% confidence intervals overlapped), suggesting an autosomal mode of sulfoxaflor resistance inheritance. The degree of dominance of 0.7 for F 1 (Sulfo-Sel Pop ♀ × Lab-Pop♂) and 0.6 for F 1 '(Sulfo-Sel Pop ♂ × Lab-Pop♀), respectively, suggested that sulfoxaflor resistance was incompletely dominant. According to the monogenic model, the number of genes involved to induce sulfoxaflor resistance revealed that sulfoxaflor resistance was polygenic in nature. The realized heritability (h 2 ) value for sulfoxaflor resistance was 0.2. The synergists experiment indicated that esterases were involved in the sulfoxaflor resistance mechanism in DCB., Conclusions: The current results indicate that there is autosomal, incompletely dominant and polygenic inheritance of sulfoxaflor resistance in DCB. Our results would be helpful in delaying sulfoxaflor resistance against DCB in the field. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

Background: Sulfoxaflor has been considered as a new tool for Nilaparvata lugens control in the field. In this study, a laboratory-selected resistant strain and a susceptible strain were used to evaluate the inheritance and fitness costs of sulfoxaflor resistance in N. lugens., Results: The resistant strain (SFX-SEL) showed 123.63-fold resistance compared with the susceptible strain (SS). Progenies of reciprocal crosses (F 1 RS and F 1 SR) showed similar concentration-mortality responses (LC 50 ) to sulfoxaflor and also exhibited a similar degree of dominance; -0.16 for F 1 RS and -0.26 for F 1 SR. Significant differences between the observed and expected mortalities of F 2 individuals suggested that sulfoxaflor resistance is associated with multiple genes. The resistant strain had a relative fitness of 0.75 with substantially decreased female adult period, oviposition days, total fecundity, egg hatchability and female adult survival rate, and prolonged pre-adult period and total pre-oviposition period., Conclusion: Sulfoxaflor resistance in N. lugens was inherited as autosomal, incompletely recessive and multigene. The development of resistance may have a significant fitness cost for the resistant population. Current research provides valuable information for researchers to establish management strategies to delay the development of sulfoxaflor resistance and control N. lugens sustainably in the field. © 2019 Society of Chemical Industry., (© 2019 Society of Chemical Industry.)

Background: Sulfoxaflor is a new insecticide for controlling Nilaparvata lugens in the field. This study was conducted to investigate the risk of resistance development, the cross-resistance spectrum and the mechanisms of sulfoxaflor resistance in N. lugens., Results: A sulfoxaflor-resistant strain was obtained from a field population by successive selection with sulfoxaflor for 39 generations in the laboratory. Sulfoxaflor-resistant populations showed significant levels of cross-resistance to dinotefuran, nitenpyram, thiamethoxam, clothianidin, imidacloprid and cycloxaprid. However, they exhibited only minor or no cross-resistance to isoprocarb, etofenprox, chlorpyrifos, triflumezopyrim and buprofezin. Sulfoxaflor was synergized by the inhibitor piperonyl butoxide (PBO) in the sulfoxaflor-resistant strain (SFX-SEL) with 2.69-fold relative synergistic ratios compared with the unselected strain (UNSEL). Compared with UNSEL, the P450 enzyme activity of SFX-SEL was increased 3.50 times, and eight P450 genes were upregulated more than 2.0-fold in SFX-SEL. RNAi reduced the expression of CYP6ER1 (36.87-fold change) and significantly enhanced the susceptibility of SFX-SEL to sulfoxaflor., Conclusion: Resistance development and cross-resistance risk of sulfoxaflor-resistance in N. lugens is evident. The enhanced detoxification of P450 enzymes caused by upregulation of several P450 genes is considered to be the metabolic resistance mechanism. These results suggest that CYP6ER1 might play an important role in sulfoxaflor resistance in N. lugens. © 2018 Society of Chemical Industry., (© 2018 Society of Chemical Industry.)

Background: The discovery of sulfoxaflor (Isoclast™ active) stemmed from a novel scaffold-based approach toward identifying bioactive molecules. It exhibits broad-spectrum control of many sap-feeding insect pests, including aphids, whiteflies, hoppers and Lygus. Systematic modifications of the substituents flanking each side of the sulfoximine moiety were carried out to determine whether these changes would improve potency., Results: Structure-activity relationship (SAR) studies showed that, with respect to the methylene linker, both mono- and disubstitution with alkyl groups of varying sizes as well as cyclic analogs exhibited excellent control of cotton aphids. However, against green peach aphids a decrease in activity was observed with substituents larger than ethyl as well as larger cycloalkyl groups. At the terminal tail there appeared to be a narrow steric tolerance as well, with linear groups or small rings more active against green peach aphids than bulkier groups., Conclusion: A novel series of compounds exploring the substituents flanking the sulfoximine moiety of sulfoxaflor were prepared and tested for bioactivity against cotton aphids and green peach aphids. SAR studies indicated that a decrease in green peach aphid potency was observed at the methylene linker as well as at the terminal tail with bulkier substituents. A quantitative structure-activity relationship analysis of the compounds revealed significant correlation of activity with two molecular descriptors, vol (volume of a molecule) and GCUT_SMR_3 (molar refractivity). This predictive model helps to explain the observed activity with the various substituents. © 2016 Society of Chemical Industry., (© 2016 Society of Chemical Industry.)

Background: Sulfoxaflor (Isoclast™ active), a new sulfoximine-class insecticide, targets sap-feeding insect pests, including those resistant to neonicotinoids. Sulfoxaflor acts on the insect nicotinic acetylcholine receptor (nAChR) in a distinct manner relative to neonicotinoids. Unlike any of the neonicotinoids, sulfoxaflor has four stereoisomers. A homology model of Myzus persicae (green peach aphid) based on the ACh binding protein from Aplysia californica, overlaid with M. persicae nAChR sequence (α2 and β1 subunits) was used to investigate the interactions of the sulfoxaflor stereoisomers with WT and R81T versions of the nAChR., Results: Whole-molecule van der Waals interactions are highly correlated with the binding affinity for the neonicotinoids and correctly predict the rank order of binding affinity for neonicotinoids and sulfoxaflor. The R81T mutation in M. persicae nAChR is predicted to have much less effect on binding of sulfoxaflor's stereoisomers than that of the neonicotinoids., Conclusion: All four stereoisomers predictably contribute to the activity of sulfoxaflor. The WT and R81T nAChR homology models suggest that changes in a whole-molecule electrostatic energy component can potentially explain the effects of this target-site mutation on the pattern of reduced efficacy for the modeled neonicotinoids, and provide a basis for the reduced effect of this mutation on sulfoxaflor. © 2016 Society of Chemical Industry., (© 2016 Society of Chemical Industry.)

Background: Sulfoxaflor, a new insecticide from the sulfoximine chemical family, and imidacloprid, a widely used neonicotinoid insecticide, were tested to assess the susceptibility and feeding behaviour of two populations of Myzus persicae: Mp61, which exhibited target-site R81T resistance to neonicotinoids, and Mp1989, a laboratory clone maintained since 1989 as a susceptible reference., Results: The imidacloprid LC50 value for Mp61 was 16 times higher than for Mp1989, showing a moderate level of resistance. Sulfoxaflor LC50 values for Mp61 and Mp1989 were much closer. The probing behaviour, as assessed by electrical penetration graphs (EPGs), of both populations was clearly altered by sulfoxaflor, which reduced the ability of aphids to find and feed from the phloem. The feeding behaviour of the susceptible Mp1989 population was much more severely affected than the moderately resistant Mp61 population on imidacloprid-treated plants. PCR assays of both aphid populations followed by DNA sequencing identified differences between populations in the point mutation in the β-subunit of the nicotinic acetylcholine receptor linked to the resistant gene against the neonicotinoid insecticide., Conclusions: Sulfoxaflor provoked feeding cessation more rapidly than imidacloprid in both aphid populations. Sharp differences in feeding behaviour were detected between the susceptible and the moderately resistant neonicotinoid-resistant aphid populations. The EPG technique can be used as a useful tool to give new insights into the functional effects of new chemical compounds and for early detection of low to moderate levels of resistance of sap-feeding insects to insecticides. The potential of this technique was validated by molecular analysis of the R81T mutation target site., (© 2015 Society of Chemical Industry.)

Background: Sulfoxaflor, a new insect control agent developed by Dow AgroSciences, exhibits broad-spectrum control of many sap-feeding insect pests, including aphids, whiteflies, leafhoppers, planthoppers and lygus bugs. During the development of sulfoxaflor, structure-activity relationship (SAR) exploration of the sulfoximine functional group revealed that the nature of the sulfoximine nitrogen substituent significantly affects insecticidal acitivity. As part of the investigation to probe the various electronic, steric and lipophilic parameters at this position, a series of N-heterocyclic sulfoximines were synthesized and tested for bioactivity against green peach aphid., Results: Using a variety of chemistries, the nitrile substituent was replaced with different substituted five- and six-membered heterocycles. The compounds in the series were then tested for insecticidal acitivty against green peach aphid in foliar spray assays. In spite of the larger steric demand of these substituents, the resulting N-heterocyclic sulfoximine analogs displayed good levels of efficacy. In particular, the N-thiazolyl sulfoximines exhibited the greatest activity, with LC50 values as low as 1 ppm., Conclusions: The novel series of N-heterocyclic sulfoximines helped to advance the current knowledge of the sulfoxaflor SAR, and demonstrated that the structural requirement for the sulfoximine nitrogen position was not limited to small, electron-deficient moeities, but rather was tolerant of larger functionality., (© 2014 Society of Chemical Industry.)

Background: Insecticides are important tools for managing damaging insect pests. Compounds that are effective against pests such as the whiteflies Bemisia tabaci and Trialeurodes vaporariorum, which show resistance to a range of insecticidal modes of action (MOA), have particular value as components of resistance management programmes. The sulfoximine insecticides are chemically unique as the first to incorporate a sulfoximine functional group. Sulfoxaflor is the first sulfoximine compound under commercial development for the control of sap-feeding insects. Its cross-resistance relationships were investigated by comparing the responses of field-collected strains with those of insecticide-susceptible laboratory strains of B. tabaci and T. vaporariorum., Results: Sulfoxaflor exhibited very low (less than threefold) resistance ratios (RR) when tested against strains of B. tabaci that produced RR of up to 1000-fold to imidacloprid and cross-resistance to other neonicotinoid insecticides. Similarly, sulfoxaflor was not cross-resistant in a strain of B. tabaci exhibiting resistance to a pyrethroid (deltamethrin) and an organophosphate (profenophos). No cross-resistance was observed between sulfoxaflor and imidacloprid in T. vaporariorum. One population of the three field strains tested showed slightly reduced susceptibility to sufloxaflor with an RR of 4.17. By comparison, this same population exhibited an RR of more than 23.8-fold for imidacloprid relative to the susceptible population., Conclusion: In spite of sharing a target site with neonicotinoids (the nicotinic acetylcholine receptor), sulfoxaflor was largely unaffected by existing cases of neonicotinoid resistance in B. tabaci and T. vaporariorum. Neonicotinoid resistance mechanisms in these whitefly species are known to be primarily based on enhanced detoxification of insecticide. This lack of cross-resistance indicates that sulfoxaflor is a valuable new tool for the management of sap-feeding pests already resistant to established insecticide groups., (© 2012 Society of Chemical Industry.)

Background: The commercialization of new insecticides is important for ensuring that multiple effective product choices are available. In particular, new insecticides that exhibit high potency and lack insecticidal cross-resistance are particularly useful in insecticide resistance management (IRM) programs. Sulfoxaflor possesses these characteristics and is the first compound under development from the novel sulfoxamine class of insecticides., Results: In the laboratory, sulfoxaflor demonstrated high levels of insecticidal potency against a broad range of sap-feeding insect species. The potency of sulfoxaflor was comparable with that of commercial products, including neonicotinoids, for the control of a wide range of aphids, whiteflies (Homoptera) and true bugs (Heteroptera). Sulfoxaflor performed equally well in the laboratory against both insecticide-susceptible and insecticide-resistant populations of sweetpotato whitefly, Bemisia tabaci Gennadius, and brown planthopper, Nilaparvata lugens (Stål), including populations resistant to the neonicotinoid insecticide imidacloprid. These laboratory efficacy trends were confirmed in field trials from multiple geographies and crops, and in populations of insects with histories of repeated exposure to insecticides. In particular, a sulfoxaflor use rate of 25 g ha(-1) against cotton aphid (Aphis gossypii Glover) outperformed acetamiprid (25 g ha(-1) ) and dicrotophos (560 g ha(-1) ). Sulfoxaflor (50 g ha(-1) ) provided a control of sweetpotato whitefly equivalent to that of acetamiprid (75 g ha(-1) ) and imidacloprid (50 g ha(-1) ) and better than that of thiamethoxam (50 g ha(-1) )., Conclusion: The novel chemistry of sulfoxaflor, its unique biological spectrum of activity and its lack of cross-resistance highlight the potential of sulfoxaflor as an important new tool for the control of sap-feeding insect pests., (Copyright © 2010 Society of Chemical Industry.)