Infestation and timing of use of non-crop plants by Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) in the Okanagan Basin, Canada

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), was first detected in 2009 in the Okanagan Basin, British Columbia, Canada. During 2010–2016, 94 570 fruits of 35 non-crop species, from 12 plant families, were collected from 101 sites where adult D. suzukii flies were trapped, and incubated in a controlled environment. In total, 450 adult D. suzukii emerged from 62 of 929 fruit collections, and from 10 host plant species in five families, of which six species are native to the region. Five plant species are reported for the first time as hosts of D. suzukii, and 11 species for the first time as non-hosts. Measures of fly occurrence and infestation reveal it to be relatively abundant in five hosts and low in others. The fly reproduced in a succession of host plants, with first infestation of each from mid-July through mid-September, and was present until mid-October, but overwintering stages were not found. Degree-day accumulations for the infested period suggest that three to five generations of D. suzukii developed on non-crop plants and formed a large contribution to the annual increases observed in trap counts in a semi-arid cold winter climate, with implications for many strategies of pest management.