Abstract: In this paper, the pest rodent economic thresholds of corn, soybean, peanut and sweet potato are determined. The daily appetites of each species of rodents are determined by saturated supply with seeds, stems and leaves of the crops as well as wild grasses. Taking daily appetite ratios as equivalent coefficients of damage intensities of each species of rodents, it is considered that oneApodemusagrarus equals to 0.599 Cricetulus triton and one C. barabensis equals to 0.468 A. agrarius. The rodent community capture rates are translated into equivalent ones of abundant species C. triton, and the regression equations of crop yield losses and rodent community densities (represented by the equivalent C. triton capture rates) are calculated. The dynamic economic thresholds are: corn272.70 L+1.26, soybean106.08L+2.35, peanut 223.56L+2.94 and sweet potato 3344.48L+0.27, and the statical economic thresholds are respectively 2.26,2.92,3.36 and 15.19.

Key words: Farmland rodent pests, Economic threshold, Economic injury level, O₂-limited environment, methane oxidation, methanotrophs, non-methanotrophs, community structure