Bacterial And Virus Diversity In Migratory Pests Mythimna Separata(Walker)

Mythimna separata(Walker)is one of the most important agricultural pest in China,and its sustainable control is crucial.Microbial pesticides in pest control is more and more widely used.In the present study,we investigate the viral and bacterial diversity and community existing in migratory individuals from M.separata based on viral metagenomics and 16 S r DNA high-throughput sequencing technology to systematically The species of microorganisms carried by the pests are clarified.This study provides a theoretical basis for the selection of microbial pesticides.The main results are as follows:1.Virus diversity of Mythimna separataA total of 823,132 contigs were obtained based on the analysis of virus metagenomic sequencing of M.separata.Among them,0.28% of the contigs were related to viruses.In contrast,a total of 1,079 contigs were obtained based on the analysis of viral meta-transcriptome,and 1% of the sequence was annotated to the virus.The results of species annotation showed that there were 13 virus families and 13 genera were identified from M.separata.Among them,bacteriophage annotation to 4 viral families and 3 viral genera.These viral-like contigs can be further classified into vertebrate viruses(2 genera in1 family),phages(3 genera in 4 families),arthropod virus(1 family),plant viruses(1 family)and insect viruses(5 genera in 7 families).Bioinformatics analysis reveals two new viruses for the first time: One is a novel Tymoviridae-like virus,tentatively named Mythimna separata Tymoviridae-like virus(MSTV),which shared 72.40% nucleotide sequence identity with Murindo virus(MN661046.1).The other is a novel Errantivirus-like virus,referred to as Mythimna separata Errantivirus-like virus(MSEV).Homology with the genomic nucleotide of Trichoplusia Ni TED virus(NC038512.1)was 71.65%.Viral detection rates of MSTV and MSEV in M.were 16.86%(n = 172)and 15.70%(n = 172),respectively.Phylogenetic analysis with deduced amino acid sequence of RNA dependent RNA polymerase indicated that Mythimna separata Tymoviridae-like is closely related to other members of Tymoviridae and is proposed as a new member of this family.The average monthly infection rate of MSTV in M.were 13.72%,12.42% and 36.67% during the northward migrants,mixed migrants and southward migrants.The average monthly infection rate of MSEV in M.were 13.72% and 12.42% during the northward migrants and mixed migrants,the southward migrants can reach 40%.2.Bacteria diversity and bacterial community structure of Mythimna separata during the migratory periodWe collected the migratory samples in 2013,2017 and 2018 by using 16 S r DNA high-throughput sequencing technology.Overall,83 bacterial classes,878 bacterial genus,and 333 bacterial species were detected.The most common genus were Orbus,Enterobacter,Pantoea,Enterococcus,Asaia and Morganella.We also analyzed the dominant bacterial during the three immigration period,the higher bacteria abundance in the northward migrants are Orbus,Enterococcus,Enterobacter and Erwina;Asaia,Orbus,Bacteroides,Morganella and Enterobacter are the dominant bacterial community in the mixed migrants.The bacteria carried by the southward migrants belong to the genera Enterococcus and Lactococcus.We investigate the virus and bacterial community in migratory pest of M.separata in China using the high throughput sequencing technology.The investigation results not only enriched the feline virus database,but also systematically provided the virus database of M.separata.We also found two newly discovered viruses,which provided the basic data for the early warning of the potential viral pandemic.The infection rates of the viruses carried by the natural populations of M.separata in different migratory periods were compared,and we found that the highest virus rate of the natural populations of this pest in the southbound period,indicating that the populations in the southbound period were more likely to be infected by the virus.At the same time,the dominant bacteria species in M.separata during the different migrant periods were analyzed comprehensively,and enriched the database of M.separata carrying virus and bacteria,which not only provided the background data for the M.separata carrying virus and bacteria species,but also provided the new ideas for biological control of this pest.