Abstract: The volatiles from healthy and pinewood nematode-infested branches of Pinus thunbergii were collected by distillation, and analyzed by using HPLC and GC-MS. Electroantennogram (EAG) and behavioral responses of Monochamus alternatus with different physiological status to the volatiles were investigated respectively.The results showed that unmated beetle had a greater EAG response potential to the volatiles from healthy branch than to those from infested branch, while it was reverse for mated beetle. The EAG response of unmated beetle under 15 days-old to the volatiles from healthy branch increased with its age. “Y” tube olfactory test showed unmated beetle had positive response to the volatiles from healthy branch and negative response to those from infested branch, while mated beetle showed positive response to the volatiles from infested branch and negative response to those from healthy branch. Female beetle with its age from 1 day to 15 days-old and male beetle from 1 day to 9 days-old had an increasing positive response to the volatiles from healthy branch, but the male after 9 days-old showed a negative response. It could be concluded that M. alternatus with different physiological status all had special sensitivity and selectivity to host tree.

Key words: Red soil, Natural vegetation, Cutting period