Feasibility analysis on species origin traceability by hydrogen stable isotope: sample case of Dendroctonus valens (Coleoptera: Scolytidae)

Dendroctonus valens (Coleoptera: Scolytidae) is an adventive trunk-boring pest, which can spread over long distances through natural and artificial transmission. Currently, the most effective means of prevention and control of this pest are timely monitoring and early warning. However, their implementation is usually hampered by the lack of feasible methods and tools for fast tracking and traceability.

  Objective  A traceability model that can be used to trace D. valens in China was established, based on hydrogen stable isotope technology.

  Method  The grid data of hydrogen stable isotopes of global precipitation were downloaded from the Online Isotopes in Precipitation Calculator (OIPC), and then, a zoning map of stable hydrogen isotopes of rainfall in mainland China was constructed using ArcGIS 10.4.1 (the coordinate system is Beijing 1954). The 153 D. valens adults captured in 5 regions were selected as experimental samples. The stable isotope mass spectrometer and elemental analyzer were used to measure the hydrogen stable isotope ratio (δ²H value) of the samples. Combined with the rainfall hydrogen isotope ratio of the sampling site, the data was simulated using R software.

  Result  From the zoning map of rainfall isotopes in the Chinese mainland, it can be clearly found that the δ²H isotope values of rainfall in the eastern monsoon region showed regional changes, and generally showed a gradient change from southeast to northwest. The δ²H stable isotope values of D. valens from the five geographical locations were significantly different. The δ²H stable isotope value of D. valens was positively correlated with the δ²H stable isotope value of rainfall. Based on the experimental data, a linear regression equation was established: y = 3.166x + 86.050. The t-test, F-test, R² test and residual test proved that the model fit well.

  Conclusion  The hydrogen stable isotope characteristics of D. valens and the precipitation hydrogen stable isotope in its habitat present a highly correlated linear relationship, and the precipitation hydrogen stable isotope has regular changes that can be used for discrimination in the distribution area of D. valens. Therefore, based on the mathematical model of this experiment, the traceability of D. valens in China can be realized.