Objective To investigate the resistance levels of adult Culex quinquefasciatus mosquitoes to three commonly used pyrethroid insecticides in Xingyi City, Guizhou Province, as well as to examine the changes in metabolic detoxification enzyme activities and mutations in the knockdown resistance (kdr) gene thereby providing a scientific foundation for the prevention and control of Culex quinquefasciatus in the region. Methods In 2024, the larvae of Culex quinquefasciatus were collected from different locations in Xingyi and reared to adult mosquitoes in the laboratory, and their resistance to pyrethroid insecticides was determined using the adult mosquito contact tube method. Surviving samples (resistant population) from the resistance tests were examined for the activities of mixed function oxidase (MFO), glutathione-S-transferase (GST), and non-specific esterase (NSE) using a microplate reader. The genomic DNA of individual adult Culex quinquefasciatus mosquitoes was extracted, and the voltage-gated sodium channel (VGSC) gene fragment was amplified via PCR and sequenced to analyze the mutations in the kdr gene. Results The 24-h mortality rates of adult Culex quinquefasciatus exposed to 0.25% permethrin, 0.025% deltamethrin, and 0.025% beta-cypermethrin were 1.00%, 0%, and 0.88%, respectively, indicating all populations of Culex quinquefasciatus exhibited resistance to the three pyrethroid insecticides. The activity of MFO in permethrin-resistant population followed a normal distribution, while deltamethrin-resistant and cypermethrin populations exhibited skewed distributions. The resistance ratios (RRs) for the three populations were 1.17, 1.03, and 1.07 times, respectively, with no statistically significant differences in MFO activity between field populations and susceptible strains (all P>0.05). However, the GST activities of permethrin-resistant and beta-cypermethrin-resistant field populations were 1.06 and 1.45 times higher than those of sensitive strains (P<0.05). Sequencing of the VGSC gene fragments of adult Culex quinquefasciatus resistant to pyrethroid insecticides revealed that mutations occurred solely at 1014 locus, presenting two alleles: wild type TTA(L) (1.26%) and mutant TTT(F) (98.74%). Two genotypes were identified: wild/mutant heterozygotes L/F (2.52%) and mutant homozygotes F/F (97.48%). No statistically significant differences were observed in the frequency of resistance gene mutations among populations resistant to the three pyrethroid insecticides (P>0.05). Conclusion The adult mosquitoes of Culex quinquefasciatus in Xingyi have developed resistance to three commonly used pyrethroid insecticides, with changes observed in metabolic detoxification enzyme activities and mutations in the kdr gene. The resistance of Culex quinquefasciatus in Xingyi is the result of multiple mechanisms. Understanding the resistance level and mechanism can provide a reliable basis for mosquito control and resistance management. It is recommended to enhance the monitoring of mosquitoes' resistance to insecticides, prioritize environmental management focused on eradicating breeding sites, reduce the use of pyrethroid insecticides, and rotate with other classes of insecticides to delay the onset of resistance.

OBJECTIVE: To rapidly identify the two morphologies and chemical properties of similar herbal medicines, Blumea riparia and B. megacephala as the basis for chemical constituent analysis. METHODS: UPLC-Q-Exactive-MS/MS was utilized for profiling and identification of the constituents in B. riparia and B. megacephala. Chemical pattern recognition (CPR) was further used to compare and distinguish the two herbs and to identify their potential characteristic markers. Then, an HPLC method was established for quality evaluation. RESULTS: A total of 93 constituents are identified, including 54 phenolic acids, 35 flavonoids, two saccharides, one phenolic acid glycoside, and one other constituent, of which 67 were identified in B. riparia and B. megacephala for the first time. CPR indicates that B. riparia and B. megacephala samples can be distinguished from each other based on the LC-MS data. The isochlorogenic acid A to cryptochlorogenic acid peak area ratio calculated from the HPLC chromatograms was proposed as a differentiation index for distinguishing and quality control of B. riparia and B. megacephala. CONCLUSION This study demonstrates significant differences between B. riparia and B. megacephala in terms of chemical composition. The results provide a rapid and simple strategy for the comparison and evaluation of the quality of B. riparia and B. megacephala.