VOLATIVE COMPOUNDS INDUCED BY HERBIVORY ACT AS AGGREGATION KAIROMONESFOR THE JAPANESE-BEETLE (POPILLIA-JAPONICA NEWMAN)

The Japanese beetle is a polyphagous insect that typically aggregates on preferred host plants in the field. We studied the response of Japa nese beetles to artificial damage, fresh feeding damage, and overnight feeding damage to test the hypothesis that beetles are attracted to f eeding-induced volatiles. Crabapple leaves that had been damaged overn ight by Japanese beetles or fall webworms attracted significantly more Japanese beetles than did undamaged leaves. Artificially damaged leav es or leaves freshly damaged by Japanese beetles, however, were not si gnificantly more attractive than undamaged leaves. Leaves that had bee n damaged overnight by Japanese beetles or fall webworms produced a co mplex mixture of aliphatic compounds, phenylpropanoid-derived compound s, and terpenoids. In comparison, artificially damaged leaves or leave s with fresh Japanese beetle feeding damage generated a less complex b lend of volatiles, mainly consisting of green-leaf odors. Feeding-indu ced odors may facilitate host location and/or mate finding by the Japa nese beetle.