Abstract

Preference of adult Japanese beetle (Popillia japonica Newman) for different species, varieties, and cultivars was compared among 33 crabapple (Malus Mill.), nine cherry (Prunus L.), and nine birch (Betula L.) taxa. Field-grown crabapples and cherries and container-grown birches were visually rated based on the percentage of total leaf area skeletonized by natural populations of this beetle. The largest variation in the preference of Japanese beetles was found among the crabapples, with injury ranging from 0 to 83%. Eighteen of the crabapple taxa had no significant injury. All of the cherry taxa were skeletonized in excess of 46%, suggesting little natural resistance among these plants. Eight of the birch taxa had no significant injury, while one species, B. jacquemontii, had an average injury of 16%. An additional study was conducted to evaluate the degree of resistance of selected crabapple taxa by caging beetles on branches of individual trees in no choice tests. Although beetles continued to feed on one resistant species, M. hupehensis (a species without injury under natural conditions), beetles would not feed on leaves of another resistant cultivar, M. baccata ‘Jackii’, when caged on those trees. These results indicate there is considerable potential for using resistance to adult Japanese beetle feeding as one selection criterion when choosing taxa of crabapple and birch for use in the landscape. Results also suggest that the mechanism(s) of resistance can vary and may include aspects of avoidance (low attraction of beetles) as well as antixenosis.