RESPONSE OF JAPANESE-BEETLES (COLEOPTERA, SCARABAEIDAE) TO LEAF VOLATILES OF SUSCEPTIBLE AND RESISTANT MAPLE SPECIES

We studied the close range olfactory response of Japanese beetles, Pop illia japonica Newman, to constitutive or feeding-induced volatiles fr om leaves of 4 maple species differing in susceptibility to defoliatio n. In pitfall arenas, intact leaves of susceptible species, Acer palma tum Thunberg and A. platanoides L., wee not significantly more attract ive than those of resistant maples, A rubrum L. and A. saccharinum L. Consistent with these results, the compounds emitted by intact maple l eaves were generally similar across resistance groupings. For each map le species, leaves that had been damaged overnight by Japanese beetles attracted significantly more beetles than did undamaged leaves. Beetl es did not discriminate between damaged leaves of susceptible and resi stant maple species. Significant differences were noted, however, in t he types of feeding-induced compounds emitted by susceptible and resis tant maple leaves. Specifically, leaves of susceptible species emitted relatively higher amounts of esters with fruit-like odors and the flo ral fragrance compound linalool, whereas leaves of resistant maples em itted more terpene hydrocarbons. Possible roles of volatile compounds as attractants and feeding stimulants, or as feeding deterrents, for t he Japanese beetle are discussed.