Location: Horticultural Crops Research
2013 Annual Report
Wild and ornamental fruit in residential and near crop fields were collected for laboratory no-choice tests. Fruits that were susceptible were further tested in choice tests with a currently ripening cultivated crop. In choice cages where an equal weight of two hosts were provided more SWD developed on ‘Totem’ strawberry than Indian stawberry. Hardy kiwi, redtwig dogwood, cherry laurel, huckleberry and lingonberry were more susceptible than ‘Pinot noir’ or ‘Pinot gris’ wine grapes. More eggs were laid and subsequently more flies developed in hardy kiwi, cherry laurel, and huckleberry. This indicates that files showed a preference for these hosts as ovipositional substrates. In contrast, a similar proportion of eggs were laid among dogwood and lingonberry, but significantly more developed from these hosts than the wine grapes. In this case, SWD may not prefer either host as ovipositional substrates but experience differential survival on the hosts. The wild and ornamental hosts now known to be susceptible to SWD will pinpoint critical areas in farm/home landscapes for further management and monitoring.
Natural enemies have been observed among fruits infested with SWD, and their potential as biocontrol agents were examined in the laboratory studies. The rove beetle, Atheta coriaria, is a ground dwelling predator and commercially available. It reduced the number of surviving SWD within infested blueberries 4-7 days post infestation. Entompathogenic nematodes are also commercially available. Direct application of nematodes Steinernema carpocapsae, S. feltiae, and Heterhabditis bacteriophora resulted in no or a single infected larva. Field applications of these nematode species will be unsuccessful given that infection rates were very low in a small and moist arena in the laboratory.