Genetic analyses of Japanese field vole Alexandromys (Microtus) montebelli winter diet in apple orchards with deep snow cover

The Japanese field vole Alexandromys (Microtus) montebelli is prevalent in apple orchards and is the dominant cause of damage to fruit trees during winter. A recent study revealed that the Japanese field vole bred and increased its population during winter in regions with deep snow. Understanding what food resources support the voles during winter can assist in formulating a better understanding of the factors of the annual variations in orchard damage. In this study, we sampled faeces of the voles from November 2018 to May 2021 and performed the DNA metabarcoding analysis for plant dietary profiling with a molecular marker on the internal transcribed spacer region in the nuclear genome. We obtained results from 60 samples, and the food sources detected most frequently were the broadleaf docks Rumex obtusifolius, followed by the cultivated apples Malus spp. The detection frequency of Fabaceae sp. declined after March, and the one of apple rootstocks increased instead. During March and April, the various parts of fruit trees and Rumex spp. were the main diets for most of the voles. The biomass supplied by herbaceous plants, especially Rumex spp. could affect the extent of vole damage to fruit trees in winter.