Diversity Of Intestinal Bacteriae In Three Lepidopteran Larvae Damaging Maize Ears

With the expansion of maize planting area,the change of planting methods,and the emergence of different new maize varieties,the types of maize pests have increased,and the number of dominant populations has changed and the degree of damage has increased.In recent years,Helicoverpa armigera Hübner,Conogethes punctiferalis Guenée and Ostrinia furnacalis Guenée have become more and more common in the maize field.Especially in the later period of maize growth,three lepidopteran larvae damaging maize ear can be seen on the maize ear.The damage caused a serious impact on the yield and quality of maize.In this paper,the bacterial diversity and community composition of the three lepidopteran larvae intestines damaging maize ear were studied by using traditional microbial isolation and culture methods combined with high-throughput sequencing technology to further explore the function of the intestinal bacteria and provide the theoretical basis for preventing and controlling the maize pest.The main results are as follows:1.Culturable bacteria in the intestines of three lepidopteran larvae damaging maize ear and maize endophytesA total of eight,eleven and six bacteria were isolated,cultured and identified from the intestines of H.armigera larvae,C.punctiferalis larvae and O.furnacalis larvae.And there were a total of seventeen bacteria isolated from maize endophytes.There were five common strains in the intestines of three larvae damaging maize ear and maize endophytes,belonging to three genera,namely Serratia,Klebsiella and Enterococcus,and these three genera were dominant in culturable intestinal bacteria.There were differences in phylum level between three larvae damaging maize ear.Among the culturable intestinal bacteria of H.armigera larvae,the proportion of Proteobacteria was 75%,and the proportion of Firmicutes was 25%.Among the culturable bacteria in the intestinal flora of C.punctiferalis larvae,the proportion of Proteobacteria was 39.1%,the proportion of Firmicutes was 56.5%,and the proportion of Bacteroidetes was 4.3%.Among the culturable bacteria in the intestinal flora of O.furnacalis larvae,Proteobacteria accounted for 70.6%,and the proportion of Firmicutes was 29.4%.Among the culturable maize endophytes,Proteobacteria accounted for 61.3%,and the proportion of Firmicutes and Bacteroidetes were 34.5% and 3.8%.2.Diversity of the intestinal bacteriae of three lepidopteran larvae damaging maize ear and maize endophytesA total of 132 OTUs were obtained from the intestinal bacteria of three larvae damaging maize ear and maize endophytes,which were classified into 6 phyla and 87 genera.The main phyla were Proteobacteria,Firmicutes,Actinobacteria,and Bacteroidetes.There were a total of 64,64 and 69 bacteria genera in the intestines of H.armigera larvae,C.punctiferalis larvae and O.furnacalis larvae.There were 44 common genera in the three larvae guts,and there were seven common genera in the intestines of H.armigera larvae and C.punctiferalis larvae,which were Ezakiella,Roseomonas,Finegoldia,Peptoniphilus,Bacillus,Brevibacterium.There were four common genera in the intestines of H.armigera larvae and O.furnacalis larvae,which were Haemophilus,Rikenella,Qingshengfania and unclassified_p_Proteobacteria.There were 13 common genera in the intestines of C.punctiferalis larvae and O.furnacalis larvae,which were unclassified_f_Comamonadaceae,Devosia,Delftia,Bosea,Pseudochrobactrum,Prevotellaceae_UCG-001,Novosphingobium,norank_p_Saccharibacteria,Brevundimonas,Alloprevotella,Salana,Verticia and so on.There were nine unique genera in the intestines of H.armigera larvae,including Sphingobium,Anaeroticuncus,Bradyrhizobium,Ruminococcaceae_UCG-005,Leuconostoc and so on.There were five unique genera in the intestines of C.punctiferalis larvae,which were Gordonia,Desulfovibrio,Caldicoprobacter and so on.There were three unique genera in the intestines of O.furnacalis larvae,which were Perlucidibaca,Flavisolibacter and Alistipes.The classification level of bacteria in the intestinal of three kinds of lepidopteran larvae damaging maize ear was relatively consistent,and both Firmicutes and Proteobacteria were the main phyla in the flora of the intestinal bacteria.The highest abundance of bacteria in the intestines of H.armigera larvae was Firmicutes(57.35%),followed by Proteobacteria(41.90%).The highest abundance of bacteria in the intestines of C.punctiferalis larvae was Firmicutes(57.23%),followed by Proteobacteria(42.25%)and Bacteroidetes(2.70%).The highest abundance of bacteria in the intestines of O.furnacalis larvae was Firmicutes(74.43%),followed by Proteobacteria(24.49%).The dominant genera in the intestines of H.armigera larvae were Enterococcus(69.27%),Serratia(22.77%),and Klebsiella(6.70%).The dominant genera in the intestines of C.punctiferalis larvae were Enterococcus(70.91%),Klebsiella(15.85%),and Serratia(4.40%).The dominant genera in the intestines of O.furnacalis larvae were Enterococcus(73.10%),Klebsiella(11.64%),unclassified_f_Brucellaceae(5.64%),and Serratia(4.48%).Enterococcus,Serratia and Klebsiella were the predominant bacteriae in the intestinal bacteriae composition,while Enterococcus was dominant.3.The function of intestinal bacteriae in three lepidopteran larvae damaging maize earAccording to the information matching to the KEGG database,the abundance of metabolic pathways are: transporters,ABC transporters,purine metabolism,pyrimidine metabolism,oxidative phosphorylation,bacterial secretion system,glycolysis,amino and nucleotide sugar metabolism,fructose and mannose metabolism,pyruvate metabolism and so on.In the metabolic pathways,the abundance of intestinal microbiota is much more than that of maize endophytes.