The carmine spider mite, Tetranychus cinnabarinus (Boisduval), is one of the most important pests in the agricultural industry. Avermectins, as efficient acaricides, have been extensively used in the mite control. The targets for avermectins in mammals, nematodes, and insects had already been identified as γ-aminobutyric acid and glutamate chloride channels. However, the targets for avermectins in mites are still not clear. Here, we report the cloning of 5 full-length glutamate-gated chloride channel genes (TcGluCls) and 3 γ-aminobutyric acid chloride channel genes (TcGABACls) and their expression levels in different developmental stages in T. cinnabarinus. All 8 genes were successfully silenced in 2 sets using RNAi. One set was made of 5 TcGluCls, and the other set was composed of 3 TcGABACls. Compared with the control, after gene silencing the mortalities of mites in both sets decreased significantly when treated with 2 concentrations of abamectin, lethal concentration (LC₃₀) and LC₇₀. Functional expression in Xenopus laevis oocytes and electrophysiological assays showed that these candidate targets are mediated by L-glutamate and GABA, respectively. The electrophysiological assays showed all 5 TcGluCls are sensitive to abamectin and ivermectin. Nevertheless, 3 TcGABACls are unresponsive to the same doses of these 2 acaricides. Our data suggested that TcGluCls are targets for abamectin and ivermectin. TcGABACls could not be activated by abamectin or ivermectin under current experimental conditions. However, the result of RNAi indicated that downregulation of TcGABACls decreased acaricidal activity of abamectin, suggesting that TcGABACls could not be excluded completely as targets for abamectin in mites.

The dissipation dynamics and residue of pyrazosulfuron-ethyl, bensulfuron-methyl, acetochlor, and butachlor in paddy fields at Good Agricultural Practices (GAP) condition were carefully investigated in this study. The four herbicides’ residues were determined based on a quick, easy, cheap, rugged, safe (QuEChERS) method coupled with HPLC-MS/MS and GC-MS. The limit of detection (LOD) for pyrazosulfuron-ethyl, bensulfuron-methyl, acetochlor, and butachlor in all matrices ranged from 0.04–1.0 ng. The limit of quantification (LOQ) of the four herbicides ranged from 0.01–0.1 mg/kg. Moreover, the average recoveries of the four herbicides ranged from 78.9–108% with relative standard deviations (RSDs) less than 15% at three different fortified levels for different matrices. The dissipation results indicated that the average half-lives (t_1/2) of the four herbicides in soil were in the range of 3.5–17.8 days, and more than 95% of the four herbicides dissipated within 5 days in water. Furthermore, the final residues of the four herbicides were all below the LOQ at harvest time. Such results highlight the dissipation dynamics and residue of the four herbicides in a rice cropping system and contribute to risk assessment as well as scientific guidance on the proper and safe application of herbicides in paddy fields.

Phytophagous mites, including Tetranychus cinnabarinus , are arthropods known for their wide infestation of host plants and pesticide resistance. We found that fenpropathrin-resistant female mites (YN-FeR, with target resistance: F1538I kdr mutation) exhibited significantly enhanced adaptability to various stress conditions, including exposure to different acaricides and high-temperature (34°C) and low-humidity environments (40% relative humidity). This evolution was attributed to cuticle thickening in resistant female mites. Cuticle protein CPR25 was identified as a critical gene mediating cuticle thickening. CPR25 regulated its own overexpression by producing a circular RNA, named circCPR25 , which acted as a decoy to selectively sequester and bind to the miR-34~317 cluster. This study revealed a distinctive mechanism underlying the evolution of stress resistance in spider mites. Specifically, a cuticle protein in spider mites regulates its own overexpression by producing a decoy circRNA, thereby promoting cuticle thickening and facilitating rapid adaptation to adverse conditions.