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, Popillia japonica Newman, to constitutive or feeding-induced volatiles from leaves of 4 maple species differing in susceptibility to defoliation. In pitfall arenas, intact leaves of susceptible species, Acer palmatum Thunberg and A. platanoìdes L., were not significantly more attractive than those of resistant maples, A. rubrum L. and A. sacchárinum L. Consistent with these results, the compounds emitted by intact maple leaves were generally similar across resistance groupings. For each maple species, leaves that had been damaged overnight by Japanese beetles attracted significantly more beetles than did undamaged leaves. Beetles did not discriminate between damaged leaves of susceptible and resistant maple species. Significant differences were noted, however, in the types of feeding-induced compounds emitted by susceptible and resistant maple leaves. Specifically, leaves of susceptible species emitted relatively higher amounts of esters with fruit-like odors and the floral fragrance compound linalool, whereas leaves of resistant maples emitted more terpene hydrocarbons. Possible roles of volatile compounds as attractants and feeding stimulants, or as feeding deterrents, for the Japanese beetle are discussed.