Feasibility Study On The Traceability Of Species Origin Based On Hydrogen Stable Isotopes

With the rapid development of the global economy,international trade has become increasingly frequent.Cross-regional personnel exchanges and cargo transportation have also made the spread of pests more rapid.Determining the source of invasive species and quarantine pests can carry out targeted quarantine at the place of production to cut off the spread of invasive species from the source.In view of this,this paper takes Lymantria dispar(international quarantine pests)and Dendroctonus valens(alien invasive pests)in China as the research objects,and intends to use stable isotope technology to test the isotope value of the test specimens,combined with The Online Isotopes in Precipitation Calculator(OIPC),to explore the feasibility of using stable isotope technology to trace the L.dispar and D.valens in China.The main conclusions are as follows:1)This article downloaded the global rainfall hydrogen stable isotope raster data from the OIPC database,and then used Arc GIS 10.4.1 to construct a zoning map of the rainfall hydrogen stable isotope in mainland China(the coordinate system is Beijing 1954).Based on this figure,it can be clearly seen that the distribution of hydrogen isotopes of rainfall in China is gradually decreasing from southeast to northwest.The zoning map can provide a certain degree of indication of the source of insects.2)The wings of 284 L.dispar adults captured from 5 regions were selected as experimental samples.The stable isotope mass spectrometer and elemental analyzer were used to measure the hydrogen stable isotope ratio of the samples,combined with the rainfall hydrogen isotope ratio of the sampling site,and the R software was used to analyze the data,The data was simulated and it was found that the?~2H value of the L.dispar samples increased with the increase of the?~2H value of the rainfall in the sampling site.A linear regression equation can be established between the two:y=1.186x–13.247(where x represents the ratio of stable hydrogen isotopes of rainfall and y represents the ratio of stable hydrogen isotopes of L.dispar).After T test(P<0.001,significance index is***),the explanatory variable of the equation is highly significant;after F test(P<0.001),the overall significance of the equation is high;after R~2 test,the result is 0.9913 to prove the model high degree of fit.153 adults D.valens captured from 5 regions were selected as experimental samples.The stable isotope mass spectrometer and elemental analyzer were used to measure the hydrogen stable isotope ratio of the samples,combined with the rainfall hydrogen isotope ratio of the sampling site,and the R software was used to analyze the data.The simulation results showed that the?~2H value of the D.valens samples increased with the increase of the?~2H value of the rainfall in the sampling site.A linear regression equation can be established between the two:y=3.166x+86.050(where x represents the ratio of stable hydrogen isotopes of rainfall,and y represents the ratio of stable hydrogen isotopes of D.valens).After T test(P<0.001,significance index is***),the explanatory variable of the equation is highly significant;after F test(P<0.001),the overall significance of the equation is high;after R~2 test,the result is 0.9808 to prove the model high degree of fit.On the one hand,the above studies show that the?~2H values of the samples of D.valens and L.dispar are linearly correlated with the?~2H values of the rainfall at the sampling site.On the other hand,it also points out that due to the difference in feeding methods between D.valens and L.dispar,D.valens is more sensitive to changes in hydrogen isotopes in rainfall.3)In order to verify the accuracy of the model,samples of L.dispar from Chengdu in Sichuan were selected for model back-testing.First,based on the regression model y=1.186x–13.247 between the?~2H value of the L.dispar sample and the?~2H value of the rainfall in the sampling site constructed in this paper,the?~2H measurement value of the L.dispar in Chengdu area(-64.3?-65.2)is used to calculate The rainfall?~2H value of the theoretical source location is between-43.04?-43.80,and then query the zoning map of hydrogen stable isotopes in the rainfall in mainland China constructed by the paper,find the color block corresponding to the value,and point to the following two regions——Sichuan Basin and Central China,which is distributed in a ring shape.Because the actual sampling site of the sample is located in the Sichuan Basin,the Chengdu area,which also proves that the actual source of the L.dispar sample can be obtained based on the model and method constructed in this paper.In the future,if there are D.valens and L.dispar of unknown origin(specimen to be tested),the unitary linear regression model of the two insects established in this article can be used to calculate the source of the specimens by measuring the isotope values of the insect specimens Isotope value of rainfall.By querying the zoning map of rainfall isotope in mainland China constructed in this paper,the range of the area of the specimen to be tested is obtained,so as to achieve the purpose of tracking the source of the specimen to be tested.