The Japanese beetle is a polyphagous insect that typically aggregates on preferred host plants in the field. We studied the response of Japanese beetles to artificial damage, fresh feeding damage, and overnight feeding damage to test the hypothesis that beetles are attracted to feeding-induced volatiles. Crabapple leaves that had been damaged overnight by Japanese beetles or fall webworms attracted significantly more Japanese beetles than did undamaged leaves. Artificially damaged leaves or leaves freshly damaged by Japanese beetles, however, were not significantly more attractive than undamaged leaves. Leaves that had been damaged overnight by Japanese beetles or fall webworms produced a complex mixture of aliphatic compounds, phenylpropanoid-derived compounds, and terpenoids. In comparison, artificially damaged leaves or leaves with fresh Japanese beetle feeding damage generated a less complex blend of volatiles, mainly consisting of green-leaf odors. Feeding-induced odors may facilitate host location and/or mate finding by the Japanese beetle.

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Antifungal potentials of volatile oxygenated alkyl compounds were determined by bioassay of Alternaria alternata germ tube growth. Compounds were naturally occurring lipoxygenase enzyme system products or related to them chemically. Results were based on headspace concentrations of test compounds.Among six-and nine-carbon aldehydes and ketones related to hexanal, nonanal, 3-hexanone, and 2-nonanone, respectively, the presence of an a,/3-unsaturated bond adjacent to the carbonyl moiety generally enhanced antifungal activity. Among six-carbon alcohols related to 1-hexanol, however, an a,d-unsaturated bond enhanced antifungal activity only slightly. Abundant, naturally occurring (E)-2-hexenal that higher plants emit as a response to wounding tested negatively for mutagenicity; a volatile compound modification of the Ames test with several strains of Salmonella typhimurium was used.

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