| Reference | [1]. Pest Manag Sci. 2019 Jun;75(6):1646-1654. doi: 10.1002/ps.5282. Epub 2019 Jan 7.<br />
Characterization of sulfoxaflor resistance in the brown planthopper, Nilaparvata lugens (Stål).<br />
Liao X(1), Jin R(1), Zhang X(1), Ali E(1), Mao K(1), Xu P(1), Li J(1), Wan H(1).<br />
Author information: (1)Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China.<br />
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.<br />
DOI: 10.1002/ps.5282 PMID: 30488546<br />
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[2]. J Appl Ecol. 2020 Jan;57(1):160-169. doi: 10.1111/1365-2664.13519. Epub 2019 Oct 29.<br />
Sulfoxaflor exposure reduces egg laying in bumblebees Bombus terrestris.<br />
Siviter H(1), Horner J(1), Brown MJF(1), Leadbeater E(1).<br />
Author information: (1)Department of Biological Sciences Royal Holloway University of London Egham UK.<br />
Sulfoximine-based insecticides, such as sulfoxaflor, are of increasing global importance and have been registered for use in 81 countries, offering a potential alternative to neonicotinoid insecticides.Previous studies have demonstrated that sulfoxaflor exposure can have a negative impact on the reproductive output of bumblebee colonies, but the specific life-history variables that underlie these effects remain unknown.Here, we used a microcolony-based protocol to assess the sub-lethal effects of chronic sulfoxaflor exposure on egg laying, larval production, ovary development, sucrose consumption, and mortality in bumblebees. Following a pre-registered design, we exposed colonies to sucrose solutions containing 0, 5, 10 and 250ppb of sulfoxaflor. Exposure at 5 ppb has been previously shown to negatively impact colony reproductive success.Our results showed that sulfoxaflor exposure at 5 ppb (lowest exposure tested) reduced the number of eggs found within the microcolonies (Hedge's d = -0.37), with exposed microcolonies also less likely to produce larvae (Hedge's d = -0.36). Despite this, we found no effect of sulfoxaflor exposure on ovarian development. Sulfoxaflor-exposed bumblebees consumed less sucrose solution, potentially driving the observed reduction in egg laying. Policy implications. Regulatory bodies such as the European Food Safety Authority (EFSA) are under increasing pressure to consider the potential impact of insecticides on wild bees, such as bumblebees, but sublethal effects can go undetected at lower-tier testing. In identifying just such an effect for bumblebees exposed to sulfoxaflor, this study highlights that microcolony-based protocols are a useful tool that could be implemented within an ecotoxicology framework. Furthermore, the results provide evidence for potentially negative consequences of pollinator exposure to an insecticide that is currently undergoing the licensing process in several EU member states.<br />
DOI: 10.1111/1365-2664.13519 PMCID: PMC7004077 PMID: 32055075<br />
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[3]. Insects. 2020 Feb 10;11(2):114. doi: 10.3390/insects11020114.<br />
Sulfoxaflor Residues in Pollen and Nectar of Cotton Applied through Drip Irrigation and Their Potential Exposure to Apis mellifera L.<br />
Jiang H(1)(2), Chen J(3), Zhao C(1)(2), Tian Y(1)(2), Zhang Z(1)(2), Xu H(1)(2).<br />
Author information: (1)State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China. (2)Key Laboratory of Natural Pesticide and Chemical Biology, South China Agricultural University, Guangzhou 510642, China. (3)Department of Environmental Horticulture and Mid-Florida Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Apopka, FL 32703, USA.<br />
Systemic insecticides have been applied through drip irrigation for controlling crop pests, but few studies have addressed potential negative effects of the application on non-target organisms. In this study, the safety of sulfoxaflor applied at 450 or 700 g a.i. ha-1 through drip irrigation at different times before flowering or during flowering to honey bee (Apis mellifera L.) was studied in 2016-2017 in a cotton production field in Xinjiang, China. Results showed that sulfoxaflor residues in pollen and nectar of cotton treated with sulfoxaflor at 450 g a.i. ha-1 before and during flowering through drip irrigation were either undetectable or no more than 17 μg·kg-1. Application of sulfoxaflor at 700 g a.i. ha-1 before flowering resulted in ≤ 14.2 μg·kg-1 of sulfoxaflor in pollen and < 0.68 μg·kg-1 in nectar. Sulfoxaflor applied at this higher rate during flowering had the highest residue, up to 39.2 μg·kg-1 in pollen and 13.8 μg·kg-1 in nectar. Risk assessments by contact exposure and dietary exposure showed that drip application of sulfoxaflor at the two rates before or during flowering posed little risk to honey bees. Thus, drip application of sulfoxaflor could represent an environmentally benign method for controlling cotton aphid.<br />
DOI: 10.3390/insects11020114 PMCID: PMC7074347 PMID: 32050712<br />
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[4]. Neurotoxicology. 2019 Sep;74:132-138. doi: 10.1016/j.neuro.2019.06.003. Epub 2019 Jun 15.<br />
Mode of action of sulfoxaflor on α-bungarotoxin-insensitive nAChR1 and nAChR2 subtypes: Inhibitory effect of imidacloprid.<br />
Houchat JN(1), Dissanamossi BM(1), Landagaray E(2), Mathé-Allainmat M(2), Cartereau A(1), Graton J(2), Lebreton J(2), Le Questel JY(2), Thany SH(3).<br />
Author information: (1)LBLGC USC INRA 1328, Université d'Orléans, 1 rue de Chartres, 45067 Orléans, France. (2)CEISAM UMR CNRS 6230, Université de Nantes, Faculté des Sciences et des Techniques. 2 rue de la Houssinière, BP 92208, 44322 Nantes, France. (3)LBLGC USC INRA 1328, Université d'Orléans, 1 rue de Chartres, 45067 Orléans, France. Electronic address: [email protected].<br />
Cockroach neurosecretory cells, dorsal unpaired median (DUM) neurons, express two distinct α-bungarotoxin-insensitive nicotinic acetylcholine receptor subtypes, nAChR1 and nAChR2 which are differently sensitive to the neonicotinoid insecticides and intracellular calcium pathways. The aim of this study is to determine whether sulfoxaflor acts as an agonist of nAChR1 and nAChR2 subtypes. We demonstrated that 1 mM sulfoxaflor induced high current amplitudes, compared to acetylcholine, suggesting that it was a full agonist of DUM neuron nAChR subtypes. Sulfoxaflor evoked currents were not inhibited by the nicotinic acetylcholine receptor antagonist d-tubocurarine (dTC) which reduced nAChR1. But, sulfoxaflor evoked currents were reduced in the presence of 5 μM mecamylamine which is known to reduce nAChR2 subtype. Interestingly, when 1 μM imidacloprid was added in the extracellular solution, sulfoxaflor-induced currents were significantly suppressed. Moreover, when extracellular calcium concentration was increased, bath application of 1 μM imidacloprid partially reduced sulfoxaflor activated currents when nAChR1 was inhibited with 20 μM dTC and completely suppressed sulfoxaflor currents when nAChR2 was inhibited with 5 μM mecamylamine. Our data demonstrated therefore that sulfoxaflor activates both nAChR1 and nAChR2 subtypes.<br />
DOI: 10.1016/j.neuro.2019.06.003 PMID: 31212017<br />
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[5]. Int J Environ Res Public Health. 2020 Mar 7;17(5):1740. doi: 10.3390/ijerph17051740.<br />
The Toxic Effects of Sulfoxaflor Induced in Earthworms (Eisenia fetida) under Effective Concentrations.<br />
Zhang X(1), Wang X(1), Liu Y(1), Fang K(1), Liu T(1).<br />
Author information: (1)Plant Protection Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences (CAAS), Qingdao 266101, China.<br />
Sulfoxaflor is a new kind of neonicotinoid insecticide that is used to control sap-feeding insect pests. In this study, a hazard assessment of sulfoxaflor on soil invertebrate earthworms was performed under effective concentrations. The results showed that different exposure times and doses had significant influence on the toxicity of sulfoxaflor. Sulfoxaflor degraded quickly in artificial soil with a degradation rate of 0.002-0.017 mg/(kg·d) and a half-life of 12.0-15.4 d. At 0.5 mg/kg and 1.0 mg/kg, the ·OH- content, antioxidant enzyme activeities, thiobarbituric acid reactive substances (TBARS) content and 8-OHdG content had significant differences compared to those in the control group. On the 56th day, significant differences were only observed in the Glutathione S-transferase enzyme (GST) activity and 8-OHdG content at 1.0 mg/kg compared to those in the control group due to the degradation of sulfoxaflor. This indicated that the risk of sulfoxaflor to earthworms was reduced because it was easily degraded in soil. However, because sulfoxaflor is a super toxic pollutant to earthworms, high concentrations of sulfoxaflor should not be released into the soil environment.<br />
DOI: 10.3390/ijerph17051740 PMCID: PMC7084856 PMID: 32155971
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