Decoding chemical profiles in insect‐induced gall development: Insights from P hacopteron lentiginosum – G aruga pinnata interactions

Galls are specialized plant structures derived from the interactions between plants and gall‐inducing insects. Infestation by the gall inducers stimulates the production of both volatile and nonvolatile metabolites including volatile organic compounds (VOCs), which function as important mediators of chemical communication between the plant, the gall inducer and associated organisms. The present study was aimed at characterizing the extractable volatile and nonvolatile metabolites across the three developmental stages (3rd, 4th and 5th instar nymphal stages) of leaf galls induced by Phacopteron lentiginosum Buckton (Hemiptera: Phacopteronidae) on Garuga pinnata Roxb. (Burseraceae), in comparison with ungalled leaves (control). The extracts of three developmental stages of galls and ungalled leaves were analyzed using Gas Chromatography‐coupled‐Mass Spectrometry. Forty‐two compounds were identified across all samples, of which 38 compounds were detected exclusively in gall tissues. The chemical composition varied significantly among developmental stages: the 3rd stage exhibited the highest chemical diversity and concentration followed by 4th and 5th instars. The identified compounds are associated with cuticular wax formation, plant defense responses and semio‐chemical signaling, suggesting functional roles in gall nutrition and potential interactions with parasitoids. These findings demonstrate stage‐specific metabolic profiles during gall development. Future studies integrating early gall developmental stages, transcriptomics and behavioral assays will further elucidate the molecular and ecological mechanisms governing plant–insect gall interactions.