Host plant use by apple maggot, western cherry fruit fly, and other Rhagoletis species (Diptera: Tephritidae) in central Washington state

Host plant use by apple maggot fly, Rhagoletis pomonella (Walsh), 1867, western cherry fruit fly, Rhagoletis indifferens Curran, 1932, and other Rhagoletis species (Diptera: Tephritidae) in five cities or towns and several habitats of different commercial importance within south central Washington state was determined in 2004 to 2006. Rhagoletis pomonella larvae infested 0 to 16% of non-commercial apple trees, Malus domestica (Borkh.) Borkh., and 0 to 22.5% of wild black hawthorn, Crataegus douglasii Lindl. (Rosaceae), the first data showing R. pomonella has established within this part of the state. Rhagoletis indifferens infested 81.8 to 100% of non-commercial sweet and sour cherry trees (Prunus avium (L.) L. and Prunus cerasus L.) (0% in one area) and 21.7 to 94.7% of wild bitter cherry trees, Prunus emarginata (Dougl. ex. Hook.) D. Dietr. (Rosaceae). Rhagoletis zephyria Snow, 1894, Rhagoletis basiola (Osten Sacken), 1877, Rhagoletis tabellaria (Fitch), 1855, Rhagoletis berberis Curran, 1932, and Rhagoletis completa Cresson, 1929 infested 0 or 15.4 to 100% of their normal host plants. In south central Washington, the host breadth of P, pomonella is narrow perhaps because of the hot and dry conditions, low fly densities, and low host abundance outside of orchards. Here, R. pomonella likely can be managed to meet the strict quarantine requirements of apple export. Rhagoletis indifferens management can be confined to sweet and sour cherry trees. Responses of various Rhagoletis species to plant cues and survival of flies in dry climates need to be determined to understand patterns of host use and population densities in Washington.