Insight into spotted lanternfly’s (Lycorma delicatula) salivary gland gene expression

The spotted lanternfly (SLF) is an invasive insect pest in the United States. This sap-sucking insect is highly polyphagous and detrimental to tree-of-heaven (TOH) and grapevine plants, posing major threat to the grape and wine industry. Hemiptera insects often inject saliva into their host during their feeding activity. Insect saliva plays important roles in digestion and often mediates plant-insect interactions. This study aimed to identify genes/proteins in SLF salivary glands (SGs) and differentially expressed genes when feeding on TOH and grapevines. SGs were dissected from SLF adults fed for ~4 weeks on either Concord grape or TOH plants in captivity and sequenced through Illumina. Genes were annotated using seven databases (NR and NT from Genbank, PFAM, KOG/COG, SwissProt, KEGG, and GO). Transcript abundance was estimated by mapping reads to the reconstructed transcriptome and standardized with FPKM. The read counts were used to determine differential expression after correcting for multiple testing. The biological functions of annotated genes were determined with GO. A total of 52738 unigenes were identified in SLF SGs. 7005 genes potentially function in suppressing/inducing/modulating plant defenses. Other gene functions include digestion, host plant’s transcription, metabolism, immune responses, and detoxification, etc. 981 genes were differentially expressed between SLF fed on TOH and grape. These results suggest multiple potential roles of SLF saliva, with several genes coding for calcium-binding proteins, oxidoreductases, hydrolases, dehydrogenases, etc. This study sets the basis for future understanding of SLF interactions with their host plants and its devastating effect on grapevines.