Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2015
Publication Date: 8/1/2015
Citation: Yee, W.L., Goughnour, R.B., Hood, G.R., Forbes, A.A., Feder, J.L. 2015. Chilling and host plant/site associated eclosion times of western cherry fruit fly (Diptera:Tephritidae) and a host-specific parasitoid. Environmental Entomology. 44(4):1029-1042. Interpretive Summary: The western cherry fruit fly originated in wild bitter cherry trees but moved onto commercial sweet cherry trees when they were introduced into the western U.S. However, little is known about the differences in biology of the flies in the two host plants. Personnel at the USDA-ARS Yakima Agricultural Research Laboratory in Wapato, WA, University of Notre Dame in Indiana, and the University of Iowa in Iowa City examined the effects of chilling on emergence times of cherry fruit flies from sweet and bitter cherry and their wasp parasites. It was found that flies from bitter cherry emerged later than flies from sweet cherry and that wasps from bitter cherry flies emerged later than wasps from sweet cherry flies, suggesting that wasps respond to differences in emergence times of their host flies. Results are important for understanding how new forms of insects could originate and also for how parasites could potentially be used to suppress fly populations.
Technical Abstract: The western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is native to bitter cherry, Prunus emarginata (Douglas ex Hooker) Eaton, but ~100 years ago established on earlier-fruiting domesticated sweet cherry, Prunus avium (L.) L. Here, we determined if eclosion times of adult R. indifferens from sweet and bitter cherry differ according to the phenology of their respective host plants and if eclosion times of the host-specific parasitoid Diachasma muliebre (Muesebeck) (Hymenoptera: Braconidae) attacking bitter and sweet cherry flies differ according to the eclosion phenology of their fly hosts. Fly pupae from sweet and bitter cherry fruit were collected from sympatric and allopatric sites in Washington state, U.S., and chilled at 4.65–4.92 °C. Because timing of eclosion in R. indifferens depends on chill duration, eclosion time in wasps could also vary with chill duration. To account for this, fly pupae were chilled for 1, 2, 2.5, 3, 4, 6, or 8 months. Both flies and wasps eclosed earlier with longer chill durations. Eclosion times of sweet and bitter cherry flies from a sympatric site in central Washington did not differ. However, at allopatric sites in northwestern and central Washington, bitter cherry flies eclosed later than sweet and bitter cherry flies at the sympatric site. Correspondingly, D. muliebre parasitizing a more isolated bitter cherry fly population eclosed later than D. muliebre parasitizing earlier-emerging sweet and bitter cherry fly populations. These results provide evidence for D. muliebre rapidly responding to changes in host plant shifts by R. indifferens.