Substantially altered bacterial diversity associated with developmental stages of litchi stink bug, Tessaratoma javanica (Thunberg) (Hemiptera: Tessaratomidae)

Abstract

The mutualistic symbiotic relationship between insects and bacteria greatly influences the growth and development of host insects. Tessaratoma javanica (Thunberg) (Hemiptera: Tessaratomidae), also referred to as the litchi stink bug, has recently been established as an important insect pest of Litchi chinensis Sonn. and causes substantial yield loss in India. To design effective and environmentally safe management strategies, an understanding of the diversity and functions of microbiota harbored across the development stages is very important. The assessment of the diversity of development-associated bacteria in T. javanica and their predicted functions was conducted using 16S rRNA gene sequences obtained by the Illumina MiSeq technology. The result showed that taxonomic analysis of associated bacteria in different developmental stages includes a total of 46 phyla, encompassing 139 classes, 271 orders, 474 families, and 893 genera of bacteria. All developmental stages of T. javanica shared a total of 42.82 percent of operational taxonomic units (OTUs), with a 97 % similarity threshold. Alpha diversity indices showed maximum species richness in the egg and adult stages. The phyla Proteobacteria followed by Firmicutes, Bacteriodetes, and Actinobacteria, exhibited the highest levels of abundance across all the developmental stages of T. javanica. Microbiota were most different between the egg and the 4th nymphal stage (χ2 = 711.67) and least different between the 2nd and 4th nymphal instars (χ2 = 44.45). The predicted functions of the microbiota associated with T. javanica are mainly involved in amino acid metabolism, cell motility, cellular processes and signaling, glycan biosynthesis and metabolism, lipid metabolism, and membrane transport. The present study documentation and information on symbiotic bacteria across T. javanica life stages will prompt the development of novel biological management strategies.

Keywords: 16s rRNA; Bacterial diversity; Developmental stages; Litchi; Tessaratoma.

Graphical abstract

Fig. 1

Venn diagram showing unique and shared OTUs (924 OTUs shared among all developmental stages) among developmental stages of Tessaratoma javanica.

Fig. 2

Bar plot showing the relative abundance at phylum level in different developmental stages of Tessaratoma javanica. Upper different alphabets represent significant differences (p < 0.05) among developmental stages. NYM 2 refers to 2nd nymphal stage and NYM 4 – 4th nymphal stage.

Fig. 3

Box plot of different alpha diversity indices A) Chao 1, B) Ace, C) Simpson, and D) Shannon across the developmental stages of Tessaratoma javanica. Different alphabetical letters indicate the significant differences among developmental stages (p < 0.05). NYM 2 refers to 2nd Nymphal stage and NYM 4 refers to 4th nymphal stage.

Fig. 4

Principal coordinate analysis (PCoA) plot visualizes the beta diversity based on the Bray-Curtis dissimilarity index among developmental stages of Tessaratoma javanica (ANOSIM, R = 0.85354, P ≤ 0.001). Abbreviations of II refer to the 2nd nymphal stage, IV – 4th nymphal stage.

Fig. 5

A) LEfSe Bar diagram showing significant differences in different life stages from phylum to genus level shows enriched bacterial diversity. B) LDA (Linear discriminate analysis) score was greater than 2. The lowercase alphabet represented significant differences. Differences in the colour of nodes indicate diversity in bacterial communities across developmental stages of Tessaratoma javanica. Abbreviations of LSBE refer to egg stage, LSB2 - 2nd instar nymph stage, LSB4-4th nymphal stage, LSBF-Female stage, and LSBM-Male stage.

Fig. 6

Correlation analysis shows the relationship between major phyla. Each node represents a taxon. The blue bars represent the positive correlation and the red bars represent the negative correlation. The deeper the color of the bar (darker blue or darker red), represent the stronger the correlation.

Fig. 7

KEGG- Level 2 metabolic functions of bacterial communities associated with the different developmental stages of Tessaratoma javanica.