Relative Susceptibility, Preference, and Suitability ofCarpinusTaxa for the Japanese Beetle (Coleoptera: Scarabaeidae) 1

Nineteen Carpinus taxa were evaluated in no-choice and multiple-choice laboratory feeding bioassays for susceptibility, preference, and suitability for the adult Japanese beetle (Popillae japonica Newman). No-choice laboratory feeding bioassays revealed that only three Carpinus taxa, Carpinus caucasica Grossh., Carpinus tschonoskii Maxim., and the hybrid Carpinus caroliniana x C. coreana, were significantly less susceptible and less suitable to feeding and for reproduction by Japanese beetles. Leaf tissue removed was related to the amount of frass produced, but was not related to leaf thickness, inner or outer leaf toughness, or fecundity. Frass production did not reflect fecundity. Hybridization may have either a positive or negative effect on host susceptibility, preference, and suitability. When a moderately preferred species such as C. caroliniana Walter or C. betulus L. is crossed with a species of equal or higher susceptibility, (i.e. C. coreana Nakai, Blume, or C. laxiflora (Sieb. and Zucc.) Blume) feeding preference increases. A “C. tschonskii factor” (Maxim.) appears to affect susceptibility and preference. There does not appear to be a large pool of Carpinus taxa suitable for future tree breeding programs in areas where Japanese beetle outbreaks are common. Potential use of Carpinus taxa in urban landscapes and forests is discussed.Index words: Susceptibility, preference, suitability, Japanese beetle, Popillia japonica, Carpinus.Species used in this study: Carpinus betulus L., C. caroliniana Walter, C. caucasica Grossh, C. cordata Blume, C. coreana Nakai, C. fargesii Franch, C. japonica Blume, C. laxiflora, (Sieb. and Zucc.) Blume, C. orientalis Mill, C. tschonoskii Maxim, C. turczaninowii Hance, C. betulus x tschonoskii, C. caroliniana x betulus, C. caroliniana x (C. betulus x tschonoskii), C. caroliniana x cordata, C. caroliniana x coreana, C. caroliniana x orientalis, C. caroliniana x tschonoskii, C. caroliniana x coreana, C. cordata x C. japonica, and, Sassafras albidum (Nutt.) Nees.