Assessments of Rhagoletis pomonella (Diptera: Tephritidae) infestation of temperate, tropical, and subtropical fruit in the field and laboratory in Washington State, U.S

Authors: Yee, Wee; GOUGHNOUR, ROBERT - Washington State University

Submitted to: Journal of British Columbia Entomological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/24/2019
Publication Date: 12/31/2019
Citation: Yee, W.L., Goughnour, R.B. 2019. Assessments of Rhagoletis pomonella (Diptera: Tephritidae) infestation of temperate, tropical, and subtropical fruit in the field and laboratory in Washington State, U.S. Journal of British Columbia Entomological Society. 116(3):40-58.

Interpretive Summary: The apple maggot fly is a threat to domestic and foreign fruit markets. This threat can be reduced through knowledge of host plant use by the fly. Personnel at the USDA-ARS Temperate Tree Fruit & Vegetable Research Unit in Wapato, WA, and Washington State University in Vancouver, WA determined use of unmanaged (non-commercial) apple and hawthorn trees by the fly in WA, surveyed various fruit for use by the fly, and tested if tropical and subtropical fruits are suitable for attack by the fly. Hawthorns were used more than unmanaged apple trees; four hawthorn species of hybrids were recorded as new hosts, and most subtropical and tropical fruit were not suitable for the fly. Findings are important in that they could be useful for developing policies to protect both U.S. and subtropical fruit markets.

Technical Abstract: The threat of apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), in the Pacific Northwest of the U.S. to domestic and foreign fruit markets can be reduced through knowledge of host plant use by the fly. Here, fly use of non-orchard apple (Malus domestica Borkhausen) (Rosaceae) versus black hawthorn trees (Crataegus douglasii Lindley) (Rosaceae), of unrecorded host plants, and of tropical/subtropical fruit were determined in Washington State. Field surveys in 2013–2015 in central Washington indicated that a greater proportion of unmanaged black hawthorn (54.1%) than non-orchard apple trees (16.3%) was positive for fly larvae. In field surveys of 36 temperate fruit in 2015–2018 in western Washington, four hawthorns (one species, three hybrids) were natural hosts, producing adult flies. Mirabelle plum (subspecies) (Rosaceae) in the field and pluot (Rosaceae) and grape (Vitaceae) in the laboratory produced puparia, but were unconfirmed hosts for regulatory purposes as numbers of flies reared from them were not recorded or adult flies were not produced from them. Unmanaged sweet cherry (Rosaceae) in western Washington produced one adult fly, the first field record from Washington. Of 37 types of tropical/subtropical fruit hung in fly-infested apple trees, only mangoes (Anacardiaceae), from which adult flies had been reared in a previous study, produced puparia. Out of nine tropical/subtropical fruit in laboratory tests, Blue Java banana (Musaceae) produced puparia, although adult flies were not reared from it. Findings could be useful for developing policies to protect both U.S. and subtropical fruit markets.