Native hosts of western cherry fruit fly (Diptera: Tephritidae) in the Okanagan Valley of British Columbia

Abstract

In the Okanagan Valley, bitter cherry, <i>Prunus emarginata</i> Dougl., the principal host of the western cherry fruit fly, <i>Rhagoletis indifferens</i> Curran, was found at 3 locations only but may occur elsewhere in the Okanagan Valley in restricted habitats. The rare occurrence and unreliable fruiting habit indicate its existence is marginal. Adult <i>R. indifferens</i> were trapped on this host even though no fruit was present. This indicates that bitter cherry and probably, the less preferred native host, western choke cherry, <i>P. virginiana</i> var <i>demissa</i> (Nutt.) Torr., are both important to the ecology of isolated, low, endemic populations of <i>R. indifferens</i> in the central and possibly northern Okanagan Valley. No instances were found where endemic populations of <i>R. indifferens</i> on native hosts might have formed a host strain adapted to the earlier maturing, introduced, cultivated cherries. Widespread infestations of this pest have adapted to development on cultivated sweet and semi-sweet cherries and appear to be a recently introduced race that is distinct from the endemic populations on native hosts. <i>R. indifferens</i> on cultivated cherries had an earlier emergence peak that those on the native hosts and were not associated with the presence of bitter cherry.