Concordance of eclosion life history timing across trophic levels in communities of host plants, fruit flies, and parasitoid wasps in the Pacific Northwest, USA

Authors: Yee, Wee; HOOD, GLEN - Wayne State University; MILNES, JOSHUA - Washington Department Of Agriculture; FORBES, ANDREW - University Of Iowa; FEDER, JEFFREY - University Of Notre Dame

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2025
Publication Date: 6/19/2025
Citation: Yee, W.L., Hood, G.R., Milnes, J.M., Forbes, A.A., Feder, J.L. 2025. Concordance of eclosion life history timing across trophic levels in communities of host plants, fruit flies, and parasitoid wasps in the Pacific Northwest, USA. Environmental Entomology. Article nvaf050. https://doi.org/10.1093/ee/nvaf050.
DOI: https://doi.org/10.1093/ee/nvaf050

Interpretive Summary: Fruit flies cause major economic damage to small fruits including cherries. Parasitoid wasps can help suppress fruit fly populations, especially in non-crop habitats before fruit flies infest cherry orchards. However, differences in host plant fruiting times may affect the timing of fruit fly emergence, which could reduce the effects of biological control if the fruit flies and parasitoids mature at separate times. Researchers at the USDA-ARS in Wapato, Washington, Washington State Department of Agriculture, and Universities studied how the timing of host plant fruits impact the development of fruit flies and their parasitoids. They looked at four plant-fly systems in Washington State: Oregon grape, dogwood, snowberry, and cherry. Each plant fruited at separate times, and the fruit fly’s emergence generally matched fruit maturity. The emergence of parasitoid wasps also usually matched the development of fruit flies, but not always. These results suggest that the timing of fruit maturity influences when fruit flies and their parasitoid wasps emerge, with impacts on biological control of fruit flies and insect evolution.

Technical Abstract: Whether host plant fruiting phenology variation affects eclosion times and generates allochronic isolation across trophic levels for Rhagoletis flies (Diptera: Tephritidae) and their braconid parasitoids is largely unknown, except in the Rhagoletis pomonella (Walsh) hawthorn-apple system. Here, we investigated how fly and wasp eclosion times in 4 systems—Oregon grape, Rhagoletis berberis Curran; red osier dogwood, Rhagoletis tabellaria (Fitch); bitter cherry, Rhagoletis indifferens Curran; and snowberry, Rhagoletis zephyria Snow—in Washington state, USA correspond to host phenology. Fruiting patterns differed among plants. Oregon grape and bitter cherry fruited once in relatively narrow temporal windows, while red osier dogwood and snowberry fruited multiple times or more widely through the season. Fruiting times differed for plants from earlier to later: based on fruit set, Oregon grape < red osier dogwood = bitter cherry < snowberry; first ripening fruit, Oregon grape < bitter cherry = snowberry; percent mature fruit in early August, Oregon grape = red osier dogwood < bitter cherry < snowberry. Mean fly eclosion times generally matched host fruiting times: red osier dogwood fly < Oregon grape fly = bitter cherry fly < snowberry fly. Parasitoid and fly eclosion matched except snowberry fly wasps eclosed before bitter cherry fly wasps. Differences in eclosion times between flies or wasps resulted in allochronic isolation from 1% to 96%. Nonconcordance between timing of fruit maturity and fly/wasp eclosion may be related to differences in precise host fruit or fly stages attacked by different species. Fruiting phenology may select for variable fly eclosion times, leading to a range of allochronic isolation between different Rhagoletis species and their associated guilds of parasitoid wasps.