The role of plant hormones in spotted lanternfly-grapevine interactions

The spotted lanternfly (SLF), Lycorma delicatula is an invasive species in the United States that has become a significant pest in vineyards. SLF feeds voraciously on plant tissues using its piercing and sucking mouthparts through which it injects saliva and uptakes plant sap. Despite its impact, research on fundamental mechanisms mediating SLF interactions with their predominant hosts (grapevines and tree of heaven -TOH) is limited. This study quantifies plant hormones in salivary glands of SLF adults fed on grapevines and TOH as well as hormones in grapevines fed by SLF adults using LC/MS. The salivary glands of SLF contain salicylic acid (SA), abscisic acid (ABA), 12-oxo-phytodienoic acid, indole-3-acetic acid (IAA), jasmonic acid, jasmonic acid isoleucine (JA-ILE), and the cytokinin ribosides -zeatin and cis-zeatin. While the concentrations of these hormones were similar in insects fed on grapevines and TOH, ABA was more abundant in insects fed on grapevines, and JA-ILE was only detected in insects fed on grape. Quantification of these hormones in grapevines infested with 10 SLF adults showed a significant increase of ABA 14 and 21 days after insect infestation, higher IAA at days 3, 5, and 21, and higher SA levels at day 3 compared with non-SLF-infested vines. These results are discussed in the context of the possible implications that these hormones may have on the regulation of plant defenses. This study contributes to our understanding of the composition of SLF saliva and its potential role in plant immunity, as well as grapevine defense responses to SLF feeding.