Surveillance Strategies of Rodents in Agroecosystems, Forestry and Urban Environments

Rodents belong to the group of occasionally economically significant to very significant pests. Some species, especially synanthropic species, cause material damage in various ways. Successful and sustainable management of rodent control strategies requires different procedures such as prevention and rodent control measures. The present study gives an overview of the most common rodent species and methods for estimating the rodent population to assess the risk of economic damage that may occur due to rodents feeding in field crops, gardens, orchards, and young forest plantations, as well as contamination of stored food. As a prerequisite for effective integrated control of mice and voles, it is necessary to implement an adequate long-term monitoring system of these species, as they are primary pests. The integrated approach improves the treatment efficacy and reduces the treatment costs but also is considered ecologically friendlier compared to conventional measures. An integrated approach should provide an effective strategy for rodent management and control in all types of rodent habitats, from agricultural and forestry production fields to residential and public areas. By combining different preventive measures, it is possible to prevent the presence of pests, which will therefore result in a reduction of pesticide use.

Long-term changes in a small mammal community in a temperate zone meadow subject to seasonal floods and habitat transformation

We tested small mammal (SM) community response to the influence of seasonal floods and habitat transformation in a temporal zone meadow (west Lithuania). The habitat transitioned from a natural flooded meadow in 2008-2012 to a mowed and pastured area in 2020. SM were trapped in late summer to autumn using lines of 25 traps (145 in total), the number of trapping sessions being one or several per year. We tested the hypotheses that: (1) any reaction to the multiple disturbances is species-specific, that is, the relative abundance of SM species and their proportion in the community differs with respect to the flood magnitude and habitat transformation, and (2) at the guild level, disturbances favor habitat generalists, thereby changing the characteristics of SM community. The average relative density of SM was 20.25 individuals per 100 trap nights (range 7.56-40.67), with 4-year-long cyclical changes of density observed. In separate years, we recorded from 4 to 9 species; Shannon's diversity index varied from 0.46 to 2.19, with expressed change of the dominant species. Habitat generalist species were favored, while habitat specialists were disadvantaged. As the meadow transformation progressed, unfavored states in the SM community prevailed, with excessive numbers of granivore and herbivore species present. Our study suggests that multiple disturbances may lead to an increase in relative abundance, species richness, and diversity within the SM assemblages.

Stable Isotopes Reveal the Dominant Species to Have the Widest Trophic Niche of Three Syntopic Microtus Voles

Simple Summary

Diets and the trophic positions of animals are fundamental issues in their ecology. We analysed the isotopic niches (as a proxy for trophic niches) of common (Microtus arvalis), field (M. agrestis), and root (M. oeconomus) voles co-occurring in orchards, berry plantations, and nearby meadows using isotopic (δ¹⁵N and δ¹³C) compositions from hair samples. We tested if the niche of the dominant common vole was widest, whether its width was related to the presence of other Microtus species, and whether there were intraspecific differences in average δ¹³C and δ¹⁵N stable isotope values. The obtained results showed relative stability in the trophic niche across the vegetative period. The isotopic niche of the common vole was the widest, exceeding the other two Microtus species by 1.6–3 times. Co-occurring vole species were separated according to δ¹³C (i.e., used different plants as main food), but they maintained similarity according to δ¹⁵N distribution. The effect of animal age and gender on the width of the trophic niche was strongest in root vole, which is a species that has spread across the country in the last 70 years. These results give new insights into the trophic ecology small herbivores, showing the impact of species co-occurrence.

Abstract

Diets and trophic positions of co-occurring animals are fundamental issues in their ecology, and these issues in syntopic rodents have been studied insufficiently. Using carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotope ratios from hair samples, we analysed the trophic niches of common (Microtus arvalis), field (M. agrestis), and root (M. oeconomus) voles co-occurring in orchards, berry plantations, and nearby meadows (as control habitat to orchards and plantations). We tested if the niche of the dominant common vole was the widest, whether its width depended on the presence of other vole species, and whether there were intraspecific differences. Results suggest stability in the trophic niches of all three Microtus species, as season explained only 2% of the variance. The widest trophic niche was a characteristic of the dominant common vole, the range of δ¹³C values exceeding the other two species by 1.6, the range of δ¹⁵N values exceeding the other two species by 1.9, and the total area of niche exceeding that of the other voles by 2.3–3 times. In the meadows and apple orchards, co-occurring vole species were separated according to δ¹³C (highest values in the dominant common vole), but they maintained similar δ¹⁵N values. Results give new insights into the trophic ecology small herbivores, showing the impact of species co-occurrence.

Glacial cycles drive rapid divergence of cryptic field vole species

Understanding the factors that contribute to the generation of reproductively isolated forms is a fundamental goal of evolutionary biology. Cryptic species are an especially interesting challenge to study in this context since they lack obvious morphological differentiation that provides clues to adaptive divergence that may drive reproductive isolation. Geographical isolation in refugial areas during glacial cycling is known to be important for generating genetically divergent populations, but its role in the origination of new species is still not fully understood and likely to be situation dependent. We combine analysis of 35,434 single-nucleotide polymorphisms (SNPs) with environmental niche modeling (ENM) to investigate genomic and ecological divergence in three cryptic species formerly classified as the field vole (Microtus agrestis). The SNPs demonstrate high genomic divergence (pairwise F ST values of 0.45-0.72) and little evidence of gene flow among the three field vole cryptic species, and we argue that genetic drift may have been a particularly important mechanism for divergence in the group. The ENM reveals three areas as potential glacial refugia for the cryptic species and differing climatic niches, although with spatial overlap between species pairs. This evidence underscores the role that glacial cycling has in promoting genetic differentiation and reproductive isolation by subdivision into disjunct distributions at glacial maxima in areas relatively close to ice sheets. Future investigation of the intrinsic barriers to gene flow between the field vole cryptic species is required to fully assess the mechanisms that contribute to reproductive isolation. In addition, the Portuguese field vole (M. rozianus) shows a high inbreeding coefficient and a restricted climatic niche, and warrants investigation into its conservation status.