Research On Rapid Identification And Environmental Risk Assessment Of Alien Invasive Insect A

Yellow crazy ant,Anoplolepis gracilipes,is a newly recorded invasive species in southern China,which seriously threaten the ecological environment and destroyed biological diversity of the invasion area.This paper mainly focuses on the three questions included the difficulty of identifying phenotype of invading insects,the unknown risk of regional diffusion and the lack of quantitative risk assessment methods.Aiming at the above problems,I respectively carried out three studies including based on the SS-PCR technology of rapid molecular identification,based on MaxEnt niche model predicting of potential geographic distribution of A.gracilipes in China and based on the quantitative evaluation index system of environmental impact of environmental risk assessment.Firestly,Morphological identification of A.gracilipes is limited by small size,high degree of similarity to related species.This study aims to develop a technique based on mitochondrial DNA cytochrome c oxidase subunit I(mtDNA COI)gene sequence for the rapid identification of A.gracilipes.The fragments of mtDNA COI gene of A.gracilipes and seven other ant species were amplified and sequenced using COI gene universal primers LCO-1490/HCO-2198.One pair of species specific COI(SS-COI)primers,APGPF and APGPR,was designed.The target fragment amplified by the SS-COI primers(APGPF/APGPR)is 374 bp in length.The species specificity and sensitivity of the primer pair were tested.The species specificity of the primer pair was validated using seven other ant species,i.e.C.irritans(Smith.1857),C.fedtschenkoi(Mayr.1877),C.nicobarensis(Mayr.1865),O.maragdina(Fabricius.1775),C.osakensis(Forel.1900),P.noda(Smith,1874),P.sp..All A.gracilipes specimens were successfully detected,and no cross reaction with other ant species was observed.The method was tested using individual worker or queen,individual 1st instar,2nd instar larva,even one grain of egg,and proved to be applicable for all of these life stages and grades.Sensitivity test results demonstrated that successful amplification could be obtained with the concentration of template DNA as low as 22.00 pg/?L,equal to 1/51200 of a whole worker of A.gracilipes.The SS-COI method developed here provides a quick,simple and reliable molecular technique for the identification and monitoring of A.gracilipes,which would be useful in detecting,monitoring and control of this new invasive ant species.Secondly,in order to reveal the potential risk of expansion and adaptive distribution of wild population of A.gracilipes,based on MaxEnt niche model predicting of potential geographic distribution of A.gracilipes in China was carried out.The existing points were divided into two parts:the native points and the integrative points,and the native prediction model and the global prediction model were constructed respectively.The global model represents the integrative model.Seven climatic environmental factors,which have a great influence on the survival of A.gracilipes,were selected for model analysis.Maxent model was adjusted by using ENMeval data package in R.Under both the default and refined parameter settings,based on the above twoprediction models,the prediction of the niche area of A.gracilipes in China were constructed respectively.The pROC protocol was used to test the reliability of the models.The results showed that in the optimization and default parameters,the AUC ratio of pROC tests of the two model were bigger than 1.It is shown that the two models both can better predict the suitable area of A.gracilipes in our country by the default parameters and optimized parameters.However,the AUC ratio of pROC test based on the local model is larger than the AUC ratio of pROC test based on the global model.Therefore,the former can better predict the suitable area of A.gracilipes in our country.As a whole,the results showed that the potential highly adaptive distribution of A.gracilipes mainly concentrated in Yunnan,Guangxi,Guangdong,Fujian,Hainan and Taiwan,and the regions of Hunan,Guizhou,Jiangxi and parts of Sichuan were medium suitable areas.But compared with the present situation of the distribution of A.gracilipes in China.the result of based on the two models under the default parameters and optimized parameters is more conservative in our country.In addition,from the global perspective of the predicted results,central Africa and north central America were the potential highly adaptive distribution of A.gracilipes.,which indirectly supports the idea that A.gracilipes originated from Africa.We believes that the definition of the local scope of A.gracilipes has a considerable impact on the prediction results.At last,in order to identify the environmental risks of A.gracilipes.risk assessment indicator system of alien terrestrial invertebrates species based on exotic possibility,colonizable possibility,spread possibility,economic and ecological risk was established.A.gracilipes was assessed quantitatively by the evaluation system,and the risk value of A.gracilipes is 3.17,which showed A.gracilipes belong to highly dangerous red invasive species according to criteria for risk grading of alien species.Therefore,this study suggested that the prevention and control research of A.gracilipes and quarantine and inspection work should be strengthened.From what have been discussed above,the results provided some helpful solutions for the rapid identification of invasive insects,the prodiction of proliferation risk and the quantitative assessment of environmental hazards,and provides reliable theoretical basis for preventing the ecological damage caused by its further expansion.