Comparative Study On The Diversity Of Bacterial Communities In Diamondback Moth (Plutella Xylostella) Gut At Different Developmental Stages

The diamondback moth (Plutella xylostella) is the most destructive pest of crucifer plants. This species is distributed in countries and regions where cruciferous vegetables are cultivated. It is considered the most widely distributed Lepidopteran pest and has become a significant threat to agricultural production. In recent years, there has been a focus on finding the natural enemies of this species and investigating the relationship between its natural enemies and the use of insect-pathogenic microorganisms to control P. xylostella. In the present study, we investigated the diversity of the gut bacteria present in the larvae, pupae and adults of the diamondback moth using bar-coded 454 pyrophosphate sequencing technology. This study could serve as a cornerstone for exploring the physiological function and ecological significance of the gut flora of the diamondback moth. Moreover, its results further the understanding of the relationship between the diamondback moth and its gut bacteria using an evolutionary and, more specifically, a coevolutionary approach, and ultimately suggest new methods for the biocontrol of the diamondback moth. The main results were as follows:The gut bacteria of diamondback moth larvae were mainly categorized into five classes. Proteobacteria Gammaproteobacteria was the major class in the larval gut (70.06%), followed by Firmicutes Bacillus, Betaproteobacteria, Alphaproteobacteria and Bacteroides Flavobacterium. Proteobacteria Gammaproteobacteria Enterobacteriaceae was the predominant family in the bacterial flora, accounting for 57.89% of the identified bacteria.It was found that the gut bacteria of the diamondback moth pupae belonged to two classes:Proteobacteria Gammaproteobacteria (99.58%) and Firmicutes Bacillus (0.42%). Gammaproteobacteria was the main class. Gammaproteobacteria Enterobacteriales Enterobacteriaceae, which contributed 99.58% of the total sequences obtained, was the dominant family in the pupal gut. The other family, Bacillus Lactobacillus Carnobacteriaceae, which belongs to Firmicutes, accounted for 0.42% of the sequences.Proteobacteria was the only phylum identified in the adult diamondback moth gut. Betaproteobacteria (0.14%) and Gammaproteobacteria (99.86%) were detected among the adult diamondback moth gut bacteria. The identified Betaproteobacteria consisted of Burkholderiales Burkholderiaceae (0.08%) and Burkholderiales Comamonadaceae (0.05%). Proteobacteria Enterobacteriales Enterobacteriaceae (99.86%), which belong to the Gammaproteobacteria, was the main family found in the adult diamondback moth gut and continued to be the most dominant gut bacteria in diamondback moth gut.The results of comparison of the gut bacteria found in the diamondback moth larvae, pupae and adults were as follows:Gammaproteobacteria Enterobacteriales Enterobacteriaceae represented the most important component of the diamondback moth gut bacteria, The differeces in gut bacteria observed in three different growth stages could be due to the growth of the diamondback moth, together with changes in its eating habits. diamondback moth larvae displayed a larger bacterial population compared to the other two growth stages. In the class-level classification, the larvae gut bacteria had three class:Proteobacteria, Firmicutes and Bacteroidetes; pupae gut bacteria had two class:Proteobacteria and Firmicutes; While the the adult gut bacteria only has Proteobacteria. In the order-level classification, the larvae gut bacteria had eight orders:Flavobacteriales (Bacteroidetes Flavobacteria), Bacillales and Lactobacillales (Firmicutes Bacilli), Sphingomonadales (Proteobacteria Alphaproteobacteria), Burkholderiales (Proteobacteria Betaproteobacteria), Enterobacteriales (Proteobacteria Gammaproteobacteria), Pseudomonadales (Proteobacteria Gammaproteobacteria) and Xanthomonadales (Proteobacteria Gammaproteobacteria); Pupal gut bacteria had two orders:Lactobacillales (Firmicutes Bacilli) and Enterobacteriales (Proteobacteria Gammaproteobacteria); The adult gut bacteria only has two orders:Burkholderiales (Proteobacteria Betaproteobacteria) and Enterobacteriales (Proteobacteria Gammaproteobacteria).