Meiwen Zhang

Dongting Lake is a biodiversity hotspot and an important food production base. Small mammals in the area are mainly rodents, which not only pose a threat to food security but also to human health. Alexandromys fortis and Apodemus agrarius are the main rodents in the area. Previously, their habitats were relatively separated, but in recent years, with changes in environmental conditions, they have invaded each other. In order to achieve effective management of rodents in Dongting Lake, long-term monitoring of land use types and rodent communities was conducted for 20 years. The results showed that the construction land continued to increase, and the arable land and forest land remained stable. During this period, there was no significant relationship between the density of A. fortis and A. agrarius and the area of different land use types, but the fatness of A. fortis was significantly correlated with water body area and construction land area. The research suggests that fatness is more suitable and sensitive than population density during the rodent monitoring.

The Dongting Lake wetland is an important habitat for rodents. In order to understand the structural characteristics of rodent communities and the effect of groundwater level on them, this study explored the changes in rodent community structure in four different habitats (Carex, Reeds, Carex + Reeds, and Poplar) from 2003 to 2023. Meanwhile, the relationships between groundwater level, nutrient composition of Carex brevicuspis, and structural characteristics of rodent communities were analyzed. The results showed that the advantages of rodent species in the four different habitats are different, and the community structure of rodents has undergone significant changes in recent years. A significant correlation between groundwater level and the nutrient composition of C. brevicuspis was found. Further analysis shows a significant correlation between the nutritional components of C. brevicuspis and the population structure of rodents. Crude protein, total phosphorus, and dry matter were three key plant nutrient indicators that were significantly correlated with both capture rate and the community diversity index (p < 0.05). Total phosphorus and crude protein were significantly negatively correlated with capture rate and Simpson’s index (p < 0.05), but significantly positively correlated with Pielou’s index and Shannon–Wiener’s index (p < 0.05), while the dry matter was completely opposite. The research conclusions suggest that different habitats and groundwater levels affect different characteristics of rodent community structures, and that plant nutrients are likely to be the mediator.

Rodents are the main wildlife species in the Dongting Lake area and can even cause significant biological disasters. In order to investigate the relationship between rodent communities and vegetation, the relationship between rodent population characteristics and vegetation cover between 2000 and 2020 was analyzed. The results showed that the rodent community in Dongting Lake has obvious spatial and temporal variability, and that Microtus fortis and Apodemus agrarius are currently the main rodent species in the area, with a higher population density in eastern Dongting Lake. Meanwhile, rodent fatness varied significantly between seasons, with the highest rodent fatness in winter at most survey sites. There was also significant spatial and temporal variability in vegetation cover, and the overall trend was increasing. There was a significant relationship between vegetation cover and rodent population density and fatness, and the relationship varied by rodent species. Microtus fortis population density was significantly correlated with medium to high levels of vegetation cover, but fatness was significantly correlated with low to medium levels of vegetation cover. The relationship between population density, fatness, and vegetation cover of A. agrarius is opposite to that of M. fortis. The study confirms that M. fortis is still the main pest rodent species in the Dongting Lake area, but the monitoring of A. agrarius and vegetation cover should be strengthened.

Plant sterilants are used to control rodent populations due to their minimal environmental risk and other ethical considerations. However, their practical utilization is unsatisfactory due to high costs and processing difficulties. Broussonetia papyrifera is a plant material that has shown the potential to inhibit the reproduction of Microtus fortis, a species that causes serious damage to crops in the Dongting Lake region in China. M. fortis was treated with different doses of B. papyrifera leaf methanol extracts. The results show that the growth of sex organs was inhibited, and the males’ testosterone levels and sperm quality were reduced. Though there were some positive effects on females, the reproductive parameters of coupled voles were inferior; the most treated couple exhibited an increased reproductive time, fetal counts, and reduced weight. It was also found that M. fortis responded negatively to the extract after a single treatment or long-term repeated treatment compared to a short-term repeated treatment. B. papyrifera leaves showed a higher application potential as a sterilant for male rodents. These findings enrich the study of plant sterilants and provide insights into the utilization of B. papyrifera and the management of rodents. Owing to the effectiveness and accessibility of the leaves, the derived sterilant may be more economical for controlling rodent pests.

Rodent damage poses a significant threat to crops, human life, and health. Compared to chemical rodent control, such as placing poisonous baits, it is more economical and environmentally friendly to use physical methods, such as building a rodent-proof wall. This study introduces a method of physically controlling harmful rodents and four methods of calculating the effect of rodents control. To understand the controlling effect of the rodent-proof wall, an investigation was conducted on the Dongting Lake beach and corresponding farmland in the embankment in April and July 2012. Our findings illustrated that the density of the reed vole Microtus fortis in the farmland with rodent-proof walls was 0.52%, significantly lower than that in the farmland without rodent-proof walls (1.76%) after artificial trapping and drug extermination (χ2 = 3.900, P = 0.048). The density of M. fortis that had migrated into the farmland in dikes with a rodent-proof wall decreased by 98.53%, significantly higher than the decrease of density in dikes without a rodent-proof wall (86.61%) (χ2 = 11.060, P = 0.01). The results demonstrated the effectiveness of rodent-proof wall control. Therefore, building a rodent-proof wall should be advocated and vigorously promoted to prevent the migration of rodents into the Dongting Lake area and similar environments, as they cause harm.

We investigated the synergistic succession of the small mammal and herbaceous communities after farmland was reconverted to seasonally flooded wetlands in the Dongting Lake Region of China. The composition of small mammals and the herbaceous community was examined in four habitat types: F (farmland), S (where agriculture continued, but human habitation ceased), R (farmland reconverted back to seasonally flooded wetlands), and B (aboriginal seasonally flooded wetlands). Using various diversity indices, the data showed that the small mammal community changed in parallel with the succession of the herbaceous community. Compared to F, there was little change in S, whereas R noticeably changed. Microtus fortis inhabited R, because Carex spp. was the dominant plant species. R held a mixture dominant species from both F and B, demonstrating that R was in transition (intermediate stages of succession) from F to B. However, the status of the small mammal community in B changed in 2008–2010, due to the op...

Density dependence plays a key role in determining the population sizes of rodents. To explore density-dependent effects on sexual development, we documented and analyzed the development of the sex organs and hormone concentrations in both sexes, and the time to maturity in females of the reed vole in response to different population densities under laboratory conditions. Weaned voles were put into either same-sex or mixed-sex groups. Upon maturity, organ coefficients were calculated for sex organs as the length or weight of the sex organ divided by the length or weight of the body, respectively. The results demonstrate that, for individuals in same-sex groups, the coefficients for uterine length and short diameter of the testis decreased as population density increased. Population density had a highly significant effect on hormone concentrations as well as time to maturity in females. Population density in mixed-sex groups affects hormone concentrations, and increases the organ coefficients for ovarian weight, uterine weight, and uterine length; however, population density had no significant effect on the time to maturity of female voles in mixed-sex groups. These experiments showed that the effect of density dependence on the development of the vole differed between same-sex and mixed-sex conditions, the effects of increased density being greater in same-sex groups. We conclude that the effect of promoting sexual development between individuals might be greater than the effect of inhibition between individuals in mixed-sex groups.

Density Effect on Postnatal Growth of Laboratory-Bred Yangtze Vole (Microtus fortis calamorum)