Volatile Profiling of Healthy and Infested Wood

After the fresh wood sections were cut down from the tree, they were immediately cut into 0.4 m sections to collect volatiles using a closed-loop dynamic headspace sampling system, as previously described by Sun et al. [49 (link)]. One milliliter of n-hexane was used to elute volatiles from traps. Plant volatiles were collected for 24 h at a 12:12 h light/dark cycle, and seven biological replicates were conducted for each treatment (healthy or infested by M. alternatus). After the volatiles collection was completed, all wood sections were cut into pieces to confirm whether they were healthy or infested by M. alternatus larvae. The collected volatiles were sent to gas chromatography-mass spectrometry (GC-MS) on a QP-2010 GC-MS instrument (Shimadzu, Japan) equipped with an HP-5 MS fused-silica column (30 m × 0.25 mm × 0.25 μm) (Agilent Technologies Inc., Santa Clara, CA, USA). Helium (1 mL/min) was used as the carrier gas, and the procedure was the same as previously reported by Sun et al. [50 (link)].