Detection Of Larvae Of Scarabaeoidea Diversity In Three Plateaus Of China Based On DNA Metabarcoding Technology

Soil ecosystem is rich in resources and has a high level of biodiversity.At present,soil ecosystem biodiversity continues to decline under the dual pressure of natural and human.Therefore,it is urgent to develop a parallel biodiversity detection technology.As an indicator insect of soil structure,larvae of Scarabaeoidea(Coleoptera,Scarabaeidae)are of great value in biodiversity conservation and soil monitoring.Accurate identification of species is the basis of all biological research.Traditional morphological identification methods are time-consuming and labor-intensive,and require professional taxonomists.DNA metabarcoding is a combination of highthroughput sequencing technology and DNA barcoding technology,which can obtain barcode gene sequences of multiple species efficiently and conveniently.This research adopts the DNA metabarcode technology in China’s Inner Mongolia plateau,Loess plateau and Tibet plateau 240 larvae of Scarabaeoidea biological samples,to a length of about 313 bp COI genes as molecular markers,combined with highthroughput sequencing and bioinformatics technology,of three plateau grubs species diversity and community composition structure parsing.The aim was to provide basic information and scientific basis for biological monitoring and diversity conservation of grubs in plateau area.In this study,OTU(Operational Taxonomic Units)clustering was performed under 94% sequence similarity threshold,and the main results are as follows:(1)A total of 19 larvae of Scarabaeoidea OTUs,belonging to 11 species and 8genera,were identified by DNA macrobarcoding in 30 samples from three plateaus in China.(2)The Chao1 index and ACE index of the Inner Mongolia Plateau ranged from14.33 to 23.50 and 11.10 to 41.00 respectively by calculating α diversity index of the three plateaues.The variation range of Chao1 index and ACE index is 10.00-16.00 and10.93-21.64 on the Loess Plateau.The Chao1 index and ACE index vary from 7.00 to28.00 and 13.00 to 46.37 on the Tibet Plateau.Among them,the highest values of Chao1 and ACE index in the Tibet Plateau both appear at point 2,and the grassland type is meadow grassland.The highest value of Chao1 index appeared at point 7 on the Loess Plateau,and the grassland type was typical grassland.The highest value of ACE index appeared at point 4,and the grassland type was typical grassland.The highest values of Chao1 and ACE index in the Tibet Plateau both appear at point 1,and the grassland type is meadow grassland.The lowest values of Chao1 and ACE index in Inner Mongolia Plateau appeared at point 9,and the grassland type was desert grassland.The lowest values of Chao1 index on the Loess Plateau appeared at point 5 and point 6,and the grassland type was typical grassland.The lowest values of ACE index all appeared at point 8,and the grassland type was desert grassland.The lowest values of Chao1 and ACE index in the Tibet Plateau both appeared at point 6,and the grassland type was typical grassland.Based on Chao1 and ACE indices,the OTU diversity of the three plateaus is Inner Mongolia Plateau > Tibet Plateau > Loess Plateau.The Shannon index varied from 0.21 to 1.86,indicating that the distribution of the OTU number of larvae of Scarabaeoidea at each point had little difference.The highest value of Shannon index was found at site 2 of the Tibet Plateau,and the lowest value was found at site 3 of the Tibet Plateau.(3)The OTU number of larvae of Scarabaeoidea in the Inner Mongolia Plateau was used to measure the change of population richness with sampling sites(p < 0.05).The OTU number of larvae of Scarabaeoidea in the Inner Mongolia Plateau showed a gradually decreasing trend with the change of sampling sites,and it began to decrease significantly from site 8.On the whole,the Loess Plateau showed a trend of increasing at first and then decreasing.The Tibet Plateau showed an overall downward trend,and it decreased significantly from the No.4 sample site.(4)The Bray-Crutis distance was used as a measure of β-diversity by comparative analysis of β-diversity among groups at different points in the three plateaus.The community structure of 10 different points in Inner Mongolia Plateau and Loess Plateau was similar(p > 0.05),and the community structure of 10 points in Tibet Plateau was significantly different(p = 0.025).Among the 10 sites on the Tibet Plateau,the community structure of site 1 was similar to that of site 8,site 3 was similar to that of site 7,site 4 was similar to that of site 6,site 9 was similar to that of site 10,and the community structure of site 2 and site 5 was different from that of other sites.(5)The three dominant species on the plateau are Amphimallon solstitiale,Aphodius fossor,and Holotrichia sp..(6)RDA ranking results showed that all the samples in Inner Mongolia Plateau and Loess Plateau and the samples No.4,No.6,No.7,No.9 and No.10 on the Tibet Plateau were mainly affected by the mean annual temperature(p = 0.014),and negatively correlated with the altitude(p = 0.043)influencing factors.The Loess Plateau No.4 sample was the most affected by the mean annual temperature.The annual precipitation(p = 0.078)had no significant effect on the different Plateau samples.