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Solenopsis invicta is a main issue in southern China and is causing significant damage to the local ecological environment. The extensive use of insecticides has resulted in the development of tolerance in S. invicta. In our study, ten S. invicta colonies from Sichuan Province exhibited varying degrees of tolerance against flonicamid, with LC 50 values from 0.49 mg/L to 8.54 mg/L. The sensitivity of S. invicta to flonicamid significantly increased after treatment with the P450 enzyme inhibitor piperonyl butoxide (PBO). Additionally, the activity of P450 in S. invicta was significantly enhanced after being treated with flonicamid. Flonicamid induced the expression levels of CYP4aa1 , CYP9e2 , CYP4C1 , and CYP6A14. The expression levels of these P450 genes were significantly higher in the tolerant colonies compared to the sensitive colonies, and the relative copy numbers of CYP6A14 in the tolerant colonies were 2.01–2.15 fold. RNAi feeding treatment effectively inhibited the expression of P450 genes, thereby reducing the tolerance of S. invicta against flonicamid. In addition, the overexpression of CYP6A14 in D. melanogaster resulted in reduced sensitivity to flonicamid. Our investigations revealed hydrophobic interactions between flonicamid and seven amino acid residues of CYP6A14, along with the formation of a hydrogen bond between Glu306 and flonicamid. Our findings suggest that flonicamid can effectively control S. invicta and P450 plays a pivotal role in the tolerance of S. invicta against flonicamid. The overexpression of CYP6A14 also increased tolerance to flonicamid. [Display omitted] • Differences in tolerance among S.invicta colonies to flonicamid was demonstrated. • Higher expression levels of P450 genes were shown in the flonicamid tolerant colony. • RNAi treatment of P450 genes reduces the tolerance of S. invicta to flonicamid. • Overexpression of CYP6A14 in D. melanogaster boosts its tolerance to flonicamid. [ABSTRACT FROM AUTHOR]

Nutrients and heavy metals (HM) in the sediment have an impact on microbial diversity and community structure. In this study, the distribution characteristics of nutrients, HM, and microbial community in the sediments along the Longsha River, a tributary of the Pearl River (or Zhu Jiang), China were investigated by analyzing samples from 11 sites. On the basis of the HM-contamination level, the 11 sampling sites were divided into three groups to explore the changes in microbial communities at different ecological risk levels. Results indicated that nutrient concentrations were higher near farmlands and residential lands, while the ecological risk of HM at the 11 sampling sites was from high to low as S10 > S2 > S9 > S6 > S11 > S7 > S5 > S8 > S3 > S4 > S1. Among these HM, Cu, Cr, and Ni had intense ecological risks. In addition, the results of Variance Partitioning Analysis (VPA) revealed a higher contribution of HM (35.93%) to microbial community variation than nutrients (12.08%) and pH (4.08%). Furthermore, the HM-tolerant microbial taxa (Clostridium_sensu_stricto_1, Romboutsia, norank_o__Gaiellales, and etc.) were the dominant genera, and they were more dynamic around industrial lands, while microbes involved in the C, N, and S cycles (e.g., Smithella , Thiobacillus , Dechloromonas , Bacter oidetes_vadinHA17 , and Syntrophorhabdus) were inhibited by HM, while their abundance was lower near industrial lands and highway but higher around residential lands. A three-unit monitoring program of land-use types, pollutants, and microbial communities was proposed. These results provide a new perspective on the control of riparian land-use types based on contaminants and microbes, and different microbial community response patterns may provide a reference for contaminant control in sediments with intensive industrial activities. [Display omitted] •Distribution characteristics and sources of pollutants were explored. •Cu, Cr, and Ni had intense ecological risks in sediments of Longsha River. •HM (35.93%) contributed more to microbial community variation than nutrients (12.08%) and pH (4.08%). •HM-resistant microbes were in higher abundance near industrial sites. • A new perspective on the control of riparian land-use types based on contaminants and microbes was proposed. [ABSTRACT FROM AUTHOR]

Residential solid fuel combustion (RSFC) is an important source of PM 2.5. Here we investigate the cytotoxicity of primarily emitted and photochemically aged PM 2.5 to A549 cells. Owing to the formation of water-soluble ions and organics (e.g., oPAHs and nPAHs), emission factors of PM 2.5 were increased by 44.4% on average after 7-day equivalent photochemical aging, which greatly altered chemical profiles of freshly emitted PM 2.5. Consequently, the cytotoxicity varied with aging duration that 2-day and 7-day aged PM 2.5 induced 22.5% and 35.1%, respectively, higher levels of reactive oxygen species than primary emissions. Similar increases were also observed for multi-cytotoxicity. Correlation analysis and western blot results collectively confirmed HO-1/Nrf-2 signaling pathway dominated the cytotoxicity of aged PM 2.5 from RSFC, which was regulated by the enhanced o-PAHs and n-PAHs during photochemical aging. Thus, aged and secondary aerosol exposure needs to be paid more attention due to the enhanced cytotoxicity and the vast crowd involved. [Display omitted] • Emission factors of PM 2.5 increased averagely 44.4% after 7-day photochemical aging. • PM 2.5 induced oxidative stress and inflammation cytokines all increased with photochemical aging duration. • OPAHs and nPAHs were the key cytotoxic substances in PM 2.5 • HO-1/Nrf-2 signaling pathway dominated the cytotoxicity of aged PM 2.5 [ABSTRACT FROM AUTHOR]