The invasive strawberry blossom weevil, Anthonomus rubi Herbst (Coleoptera: Curculionidae), uses Dasiphora fruticosa for reproduction in British Columbia

Abstract

The first North American report of the Eurasian strawberry blossom weevil, Anthonomus rubi Herbst was in the Fraser Valley of British Columbia (BC), Canada in 2019. This weevil feeds on and reproduces in closed developing flower buds of plants in the family Rosaceae, including small fruit crops, ornamental plants, and non-crop plants outside of crop fields. In its native range, A. rubi has been observed feeding and ovipositing on shrubby cinquefoil, Dasiphora fruticosa. In the Fraser Valley, D. fruticosa is a commonly grown landscaping shrub and therefore could serve as an important non-crop host for A. rubi. To investigate the potential of D. fruticosa as a host for A. rubi, we monitored four landscaping beds containing D. fruticosa for A. rubi adults, immature stages, and parasitoids that target immature stages of A. rubi during the 2022 growing season. We collected damaged flower buds weekly and monitored for weevil and parasitoid emergence. We observed A. rubi adults feeding on flowers and ovipositing in D. fruticosa buds at all field sites. Adult weevils emerged from 45% of collected clipped buds and two species of parasitoid wasps from the genus Pteromalus Swederus (Hymenoptera: Pteromalidae), emerged from A. rubi damaged buds. Parasitism levels were low at all surveyed sites, with a mean parasitism rate of 1.4%. This is the first report of A. rubi using D. fruticosa as a host plant in North America and suggests that this plant could be an important non-crop host for A. rubi in the newly invaded range, where attack by natural enemies is low.