Multiple host shifts between distantly related plants, Juglandaceae and Ericaceae, in the leaf-mining moth Acrocercops leucophaea complex (Lepidoptera: Gracillariidae)

Insect herbivores such as gall formers and leaf miners are often highly specialized and adapted to their respective natal host plants. Due to the specialization and adaptation, it is presumed that host shifts readily occur among closely related plant species. Leaf-mining moths, the Acrocercops leucophaea complex, consist of three species, A. leucophaea, A. defigurata, and A. transecta. Larvae of all the species of the complex feed on Juglandaceae plants, but A. leucophaea and A. transecta are also associated with an Ericaceae plant, which is quite distantly related to Juglandaceae. Such a host utilization as in this species complex is very rare among phytophagous insects. In the present study, we estimate the history of host shifts by reconstructing the phylogeny of the A. leucophaea complex using molecular data (partial sequence of mitochondrial COI, 12S rDNA, and ND5). Parsimony and maximum likelihood analyses indicated that the common ancestor of the A. leucophaea complex used Juglandaceae only, and that the association with Ericaceae has evolved in A. leucophaea and A. transecta independently. Parametric bootstrap analysis also supported multiple origins of the association with Ericaceae in this complex. These results imply that there are ecological and biochemical factors that promote host shifting between Juglandaceae and Ericaceae despite the two families being not closely related.