| Apis cerana is widely distributed in China.It is one of the main pollinating insect in traditional agriculture.Apis cerana has the characteristics of small body,black head and chest,black and yellow abdomen,and yellow-brown hairs covering the whole body.It has many advantages that Apis mellifera do not have,such as the ability to use sporadic nectar plants,strong harvesting power,high utilization rate,long nectaring period and adaptability,strong anti-mite and disease resistance,and low consumption of feed.It is very suitable for fixed-point breeding in Chinese mountainous areas.However,the introduction of Apis mellifefra has greatly threatened the Apis cerana’s breeding industry in China,and even caused the gradual extinction of Apis cerana in some areas.Therefore,the investigation and analysis of the distribution and germplasm resources of Apis cerana in China are particularly important.This research collected samples of Apis cerana from a total of 15 sampling locations in various regions of China,and morphological dissection was performed to prepare specimens for index measurement and analysis.The main results are as follows:1.Collection and determination of morphological indexes of Apis ceranaA total of 146 Apis cerana samples were collected from 15 areas.Morphological anatomy was selected from 5 collected 146 groups of Apis cerana,and morphological specimens were prepared.After drying,LY-WN ultra-clear microscope was used to take pictures,and the obtained pictures were indexed using LY-M-Toupview measurement and analysis software.For measurement,the selected measurement indexes include: the length of the third tergum,length of the fourth btergum,the length of proboscis,the right front wing length,the right front wing width,cubital vein a and cubital vein b,and the sum of the third and fourth tergum,the right forewing area and index number of cubiral vein are calculated.2.Analysis of the six morphological indicators of Apis ceranaThe SPSS software was used to statistically analyze the morphological indicators of Apis cerana.According to the statistics of the average value of the index and the standard deviation,it can be known that the average wing length,wing width,and wing area of the Apis cerana in Malkang are the largest,the average value of the wing length of Apis cerana in Yunnan is the smallest,and the average value of wing width and wing area of Apis cerana in Shandong was the smallest.The average T3T4 length and index number of cubiral vein of Apis cerana in Dongbei are the largest,respectively.The average value of the T3T4 length of Apis cerana in Yunnan is the smallest.The average value of index number of cubiral vein of Apis cerana in Shanxi is the smallest.The average length of proboscis of Apis cerana in western Guizhou is the largest,and the average length of proboscis of Apis cerana in Yunnan is the smallest.Correlation analysis results between morphological indicators and geographic factors show that longitude has an impact on all six morphological indicators,latitude will affect the sum of the third and fourth tergum,wing length,and index number of cubiral vein,and altitude will affect five morphological indicators other than index number of cubiral vein.the average annual temperature will affect the morphological indicators other than length of proboscis.Annual rainfall will affect the T3T4 length,wing length and wing area.Correlation results between the six indicators showed that the wing width was significantly correlated with the third and fourth tergum,length of proboscis,and wing length(p <0.05),Wing area was significantly related to the third and fourth tergum,length of proboscis,wing length,and wing width(p <0.05),and the index number of cubiral vein was only significantly related to the third and fourth tergum(p <0.05).The results of factor analysis,discriminant analysis,and cluster analysis all indicate that the morphological diversity of Apis cerana in China is extremely rich,and different geographical types of Apis cerana have different degrees of differentiation.3.Morphological Diversity of Apis cerana in different geographical regions of western SichuanThe SPSS statistical analysis of six morphological indicators of Apis cerana in western Sichuan region shows that in the correlation analysis between the six morphological indicators and geographical factors,the longitude,latitude,altitude,annual temperature and annual rainfall will all effect the sum of the length of T3+T4,wing length,wing width and wing area,and index number of cubiral vein.The results of factor analysis,discriminant analysis,and cluster analysis all show that Apis cerana in the western Sichuan area have clearly differentiated.Although the degree of differentiation is different,it can be roughly determined that Apis cerana in the northern and central Sichuan plateau can be divided into one group,and the southeastern edge of the western Sichuan mountain and the eastern edge of the western Sichuan mountain can be divided into another group.It shows that the Apis cerana in western Sichuan can be divided into the geographical types of western Sichuan plateau and western Sichuan moutain.4.Apis cerana genome extraction and resequencing analysisIn this study,genomic DNA was extracted from the collected Apis cerana samples by the CTAB method,and tested by agarose gel electrophoresis.Whole-genome sequencing was performed on the samples that passed the test.PCA cluster analysis was performed on the sequencing results.The analysis results showed that: No matter which two principal components are analyzed,the result show that,although Apis cerana in the central part of the western Sichuan plateau have differentiated,they are generally grouped with the Apis cerana in the northern part of the western plateau,Apis cerana in the western Sichuan moutains are different from those in the western Sichuan plateau.At the molecular level,it can be seen that the Apis cerana in the western Sichuan area have undergone genetic differentiation.The group structure analysis results show that when K=2,the northern/central group of the western Sichuan plateau differentiates separately,indicating that the two groups have a common ancestral group,and when K=6,the Apis cerana of the western Sichuan mountain separate as a group.At the molecular level,it is proved that the Apis cerana in the northern part of the western Sichuan plateau and the central part of the western Sichuan plateau belong to the same geographical group,while the Apis cerana in the western Sichuan mountainous area belong to another group. |
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