Abstract
Trapping by a Porapak Q column and GC-MS analysis of onion volatiles revealed 9 alkyl di- and trisulfides. Among these, dimethyl, methyl propyl and dipropyl trisulfides were newly identified in the headspace onion odor and the last two were found, for the first time, to have attractant-oviposition stimulating activity. From the bioassay tests of 24 synthetic and commercially obtained compounds, it was concluded that a propylthio moiety is essential for a compound to express the activity. These findings were discussed in relation to the host plant selection of onion fly and synergism among the onion odor components.
