Oviposition behavior and development of the invasive lily leaf beetle on native host plants from the Pacific Northwest United States

Abstract Invasive insects often feed on novel plant species related to hosts in their native range, including species of conservation concern. The lily leaf beetle, Lilioceris lilii Scopoli (Coleoptera: Chrysomelidae), a Eurasian pest of cultivated lilies, is one such invader first detected in Canada in 1943 that has spread throughout the Northeastern United States and Canada, reaching the Pacific coast by 2011. Although L. lilii is known to feed on nearly 100 plant species across several genera, it is unknown what hosts it will feed on in its new range. We addressed this knowledge gap with experiments of L. lilii on native host plants found in the Pacific Northwest, United States, where it is now well‐established and has the potential for population expansion. We conducted oviposition and larval feeding trials with Calochortus tolmiei Hook. & Arn. (Liliaceae) , Fritillaria affinis (Schult. & Schult.f.) Sealy (Liliaceae) , Lilium columbianum Leichtlin (Liliaceae), and Prosartes hookeri Torr. (Liliaceae). Trials showed that female L. lilii oviposited on all hosts tested, and larvae fed on all hosts except P. hookeri. Larvae reared on L. columbianum performed similarly well to larvae that fed on the control lilies. Individuals were only able to be reared to the adult stage on L. columbianum and C. tolmiei , although survival rates were low for C. tolmiei. With numerous susceptible native Liliaceae species of conservation concern in the Pacific Northwest, the establishment of the lily leaf beetle may constitute a new threat to these already vulnerable species across broad regions.