Comprehensive lists of suitable host plants of apple maggot, Rhagoletis pomonella (Walsh, 1867) (Diptera: Tephritidae), including new host records

Abstract

Apple maggot, Rhagoletis pomonella (Walsh, 1867) (Diptera: Tephritidae), is an introduced quarantine pest of apple, Malus × domestica (Suckow) Borkh. (Rosaceae), in western North America that is native to eastern Canada, eastern/midwestern U.S.A., and central/southern Mexico. Ancestral hosts of R. pomonella are species of hawthorns, Crataegus Linnaeus (Rosaceae), but not all Crataegus are hosts and some plants of other genera are also hosts. Identifying plants that are fly hosts may help efforts to prevent fly spread and to manage flies. Here we present updated lists of host plants of R. pomonella based on the literature and include three newly recorded hosts we discovered from 2023 and 2024 fruit collections in Washington State, U.S.A. There are 58 known host plants of R. pomonella in Canada and the U.S.A. belonging to nine genera of Rosaceae. Of these hosts, 53% belong to Crataegus, of which 81% are native to one or both countries. The newly recorded host records are Crataegus × cogswellii K. I. Chr. & T. A. Dickinson, Crataegus okennonii J. B. Phipps (O'Kennon's hawthorn), and Crataegus castlegarensis J. B. Phipps & O'Kennon (Castlegar hawthorn). In addition, reported hosts of the R. pomonella complex in Mexico include five Crataegus species as well as apple. Discovering previously unknown host plants and providing accurate lists of known hosts of R. pomonella can help reduce chances of accidental fly spread into pest-free areas via infested fruit.