Aedes albopictusis the only vector that can transmit the dengue virus in Zhejiang Province, central China, and it can develop insecticide resistance due to long-term exposure to pyrethroids. The presence of knockdown resistance (kdr) mutations is one of the mechanisms responsible for pyrethroid resistance, and has been reported in someAe. albopictuspopulations in southern China. However, little is known about the DNA diversity of the voltage-gated sodium channel (VGSC) gene inAe. albopictuspopulations in central China. FourAe. albopictusfield populations were collected, in Yiwu (YW), Quzhou (QZ), Wenzhou (WZ), and Jiaxing (JX) from Zhejiang Province, central China. The susceptibility ofAe. albopictusadults to three pyrethroids (beta-cypermethrin, deltamethrin, and permethrin) was tested using the WHO tube assay, andKdrmutations were identifiedviaPCR and sequencing. The relationship betweenkdrmutations and pyrethroid phenotypes was also analyzed. Of the four populations, none was sensitive to any pyrethroid tested, and the YW population showed the strongest pyrethroid resistance. Non-synonymouskdrmutations were detected in codons 1532 and 1534, domain III. At codon 1534, one mutant allele, TCC(S), was detected in the four populations with a frequency of 42.08%, while at codon 1532, one mutant allele, ACC(T), was detected in the JX and QZ populations, with frequencies of 4.22 and 3.03%, respectively. The F1534S mutant allele was positively correlated with both beta-cypermethrin and deltamethrin resistance phenotypes (OR > 1, P < 0.05), whereas the I1532T mutant allele was possibly negatively correlated with beta-cypermethrin, deltamethrin, and permethrin resistance phenotypes (OR < 1, P > 0.05). In conclusion, resistance and resistance mutations regarding to three pyrethroids are already present in theAe. Albopictuspopulations from Zhejiang, central China, which prompts the need to use non-insecticide-based methods of insect control.

Carbon dioxide (CO₂) attracts host-seeking adult mosquitoes; this fact is exploited for mosquito monitoring, which is important for evaluating the effects of mosquito-control operations. A field experiment was designed to explore the relationship between the CO₂ flow rate and the trapping effect of BG traps. The aim was to select an appropriate flow rate for monitoring Aedes albopictus. Six sampling sites were selected for field experiments in Hangzhou city, Zhejiang Province, China. A total of six CO₂ flow rates (0.00 L/min, 0.075 L/min, 0.15 L/min, 0.30 L/min, 0.60 L/min and 1.20 L/min) were tested to compare their effects on mosquito trapping. The catches were performed in six trapping periods between 15:30 and 18:30, and each catch period lasted 0.5 h. A total of 3068 adult mosquitoes were captured at six sampling sites in six days using BG traps (with BG-Sweetscent), among which 86.96% were Ae. albopictus. The total number of Ae. albopictus (males and females) captured at a flow rate of 0.00 L/min was significantly lower than the numbers captured at 0.075 L/min, 0.15 L/min, 0.30 L/min, 0.60 L/min and 1.20 L/min (P<0.001, P<0.001, P<0.001, P<0.001, and P<0.001 respectively). The total number of Ae. albopictus captured and the number of Ae. albopictus females captured increased with increasing CO₂ flow and peaked at 0.3 L/min, above which these capture numbers did not increase significantly. In conclusion, the appropriate CO₂ flow rate for monitoring Ae. albopictus with BG traps was 0.3 L/min.

Dengue fever (DF) is often asymptomatic in endemic areas. Asymptomatic infection during a DF outbreak in China, where DF is not endemic, has not been reported until now. In this study a total of 365 subjects from 6 villages were recruited from October 4–7, 2009. Overall, 102 subjects (27.95%) were positive for dengue virus (DENV) IgM, and 14 subjects (3.84%) were positive for DENV IgG and IgM. In different age groups, seropositive rates varied from 12.50% to 50.00% for DENV IgM, and from 0% to 11.76% for DENV IgG. Seroprevalence of DENV IgM was significantly higher than that of DENV IgG. Seroprevalence rates of DENV IgM differed among different villages. However, the seroprevalence of DENV IgM was not statistically significantly different among gender and age groups. Asymptomatic DF infection is prevalent in non-endemic areas.

Introduction: Rodents are significant vectors, harboring diverse pathogenic microorganisms which can spread a variety of infectious diseases. Surveillance on rodent density patterns should be prioritized as early warning indicators for prevention and control of infectious diseases. We aimed to analyze spatial and temporal heterogeneity of rodent density patterns in Zhejiang Province, and analyze the spatial and temporal correlations between rodent density, meteorological, land use and vegetation factors. Methods: Collect rodent surveillance data, meteorological factors, and vegetation factors in Zhejiang Province from 2019 to 2023. Analyze the temporal and spatial distribution of rodent density patterns. Employ the GTWR model to analyze the spatial and temporal correlations between rodent density, meteorological, land use and vegetation factors. Results: The rodent density in southern Zhejiang Province was higher than that in northern Zhejiang Province, and the species richness of wild rodents also exceeded that in northern Zhejiang Province. The effects of meteorological and vegetation factors on rodent density varied across geographical spatial distributions, which might primarily be related to the distribution range of rodent species in different habitat sites. Discussions: Meteorological and vegetation factors could influence the rodent density, particularly that of wild rodents, by offering a suitable environment for growth and development as well as food sources.