Resistance of ornamental lilies to feeding by the invasive lily leaf beetle, Lilioceris lilii (Coleoptera: Chrysomelidae) in Michigan

The lily leaf beetle (Lilioceris lilii), an invasive pest whose range continues to expand across the United States threatens the lily industry. Lily leaf beetles feed both on ornamental and wild lilies in the Lilium genus and on Fritillaria species. Feeding by the adult and larval stages can completely strip lilies of above ground foliage and can eventually kill lily plants. Despite its long establishment in North America, the beetle’s feeding preferences in the field are unknown. Assessing the feeding preference of beetles may help at identifying resistant lily varieties. To assess preference, 21 lily varieties categorized into main types of Asiatic, Martagon, Oriental, and Lilium henryi were monitored biweekly throughout the growing season for lily beetle abundance by life stage and percent defoliation. Defoliation at the end of the season reached almost 100% on most lily varieties, except for L. henryi that remained under 30% indicating that it is a resistant variety. Similar number of eggs were laid on the different lily varieties but, there were significantly fewer larvae on L. henryi suggesting dissonance in maternal choice and larval performance.