| Many insect lifestyles are found associated with microbiome,which have a complex relationship with their host in the long-term evolution.Research on the composition and structure of microbiome in insects is helpful to better understand the relationship between microbiome and their hosts,to further explore microbial resources,and to use microbiome to control pests.The small brown planthopper Laodelphax striatellus(Fallen)is an important agricultural pest which is one of the three most serious planthoppers in China.The main ways of damage to the crops include both direct sucking and virus spreading.There is a large number of microorganisms in L.striatellus,and these microorganisms form complex relationships with L.striatellus in long-term evolution.However,it is not clear about the composition and structure of microbial community and the interaction mechanism between microbiome and L.striatellus.Considering The outbreak and damage characteristics of L.striatellus and the potential application of microorganisms in pest control,it is neccessary to study the composition and structure of the microbial community and the interaction mechanism with L.striatellus.In this study,we first used high-throughput 16S rRNA amplicon sequencing approach to determine the microbial community in the body of the planthopper,and analyzed the composition and structure of the microbial community;secondly,we further analyzed the microbial composition and structure diversity in the head,gut and ovary of three important parts of the planthopper,and analyzed the function of microbiome on the host in different parts;then,we analyzed the influence of environmental impact factor antibiotic(tetracycline)on the microbial diversity of the planthopper,and further explore the effect of tetracycline on microbial community function.Finally,we studied the interaction between Wolbachia which is an important symbiont in the planthopper,and RSV in L.striatellus,and try to find some important microorganisms to control L.striatellus.The results are summarized as follows:Ⅰ.The composition and structure of the microbial community in the body of L.striatellusWe used a high-throughput 16S rRNA amplicon sequencing approach to systematically study and analyze the microbial community of L.striatellus.The Proteobacteria,Firmicutes,Bacteroides and Actinobacteria are high relative abundances,accounting for more than 99%of all bacteria in the body of L.striatellus.In the class level classification,Alphaproteobacteria,Bacilli,Bacteroidia,Clostridia,Actinobacteria are the highest Erysipelotrichia of erysipelotrichia is relatively high;Asaia and Wolbachia are relatively high at the genus level classification,accounting for about 77%of all bacteria in the L.striatellus,Other bacteria with high relative abundance are Bacteroides,Enterococcus,unclassified f Enterobacteriaceae,Acinetobacter,Streptoccus and Lactobacillus.The results showed that there were abundant microorganisms in L.striatellus,which provided a basis for the excavation of the microbial resources.Ⅱ.Composition and structure diversity of microbial community in different parts of the L.striatellusAfter the analysis of the microbial community in the body of the planthopper in the previous chapter,we further studied the microbial community in the head,intestine and ovary of the important parts of L.striatellus,in order to reveal the function and influence of microbiome in different parts of L.striatellus.By comparing the composition and structural diversity of the microbiome in the three parts,we found that Proteobacteria,Firmicutes and Bacteroidetes are the dominant bacterial groups in each part of the planthopper.The results of PCoA analysis showed that the bacterial community was clustered according to the different parts(gut,head and ovary),and the bacterial community in the intestines was different from that in the head and ovary.The dominant microbiome in the three parts was also different.The relative abundance of Asaia was the highest in the intestines,while that of Wolbachia was higher in the head and ovary.We also found that there are significant differences among the three parts in some nutrient metabolism pathways by the functional analysis of the microbial community in three parts.The results showed that there were differences in microbial community composition and structural diversity in different parts of L.striatellus and the effect of microbiome in different parts on the planthopper is also different,which further shows that the effect of microbiome in different parts on the host is different.Ⅲ.The effect of antibiotic treatment on the diversity of composition and structure of microbial community in L.striatellusAfter a systematic study of the microbiome in different parts of the body,we also explored whether environmental factors could affect the microbiome in L.striatellus.We analyzed the microbial community diversity of environmental factor antibiotic(tetracycline)treated and untreated L.striatellus by using 16S rRNA amplicon high-throughput sequencing technology.The results showed that antibiotics changed the composition and structure of the microbial community.Tetracycline treatment significantly reduced the relative abundance of Firmicutes and Bacteroides,but the relative abundances of Proteobacteria increased significantly.Tetracycline treatment reduced the relative abundance of Wolbachia,Bacteroides and Enterococcus,but the relative abundance of Asaia was not affected by tetracycline.After tetracycline treatment,the relative abundance of Proteobacteria in the head and ovary decreased significantly,while that in the gut increased.In addition,the relative abundance of Firmicutes and Bacteroides bacteria in the gut was significantly lower than that in the head and ovary,the results of functional analysis showed that antibiotics had a great effect in gut.The results showed that antibiotics had an effect on the composition and diversity of bacterial community,which provided a new way to control L.striatellus.Ⅳ.The relationship between Wolbachia and RSV in L.striatellusWe found that Wolbachia is relatively abundant and widely distributed in L.striatellus and previous studies have found that Wolbachia can inhibit the proliferation of virus in many insects.We studied the interaction between Wolbachia and rice stripe virus(RSV)in L.striatellus.We found that RSV can reduce the hatching ability of the host,but it has no effect on the density of Wolbachia in L.striatellus.In addition,we observed that Wolbachia has no effect on the density and infection rate of RSV,and Wolbachia and RSV can maintain a mild relationship in L.striatellus.The results provide a basis for further using Wolbachia to prevent plant viruses in agricultural pests.In summary,this study first clarified the composition and structure of the microbial community in the body of L.striatellus,further explored the composition and structural diversity of the microbial community in the head,gut and ovary of L.striatellus,and clarified the impact of antibiotics on the microbial community diversity in L.striatellus;in addition,it explored the relationship between symbiotic bacteria Wolbachia and the rice stripe virus(RSV)in L.striatellus.The results are helpful to provide theoretical guidance for the comprehensive control and agricultural production safety. |
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