The Eurasian strawberry blossom weevil, Anthonomus rubi (Herbst, 1795), is established in North America

We report the strawberry blossom weevil, Anthonomus rubi (Herbst, 1795) (Coleoptera: Curculionidae), a species native to Europe, Asia, and North Africa, as established in British Columbia, Canada. This is the first report of A. rubi in North America. We provide a diagnosis of the species and compare it with other species of the genus Anthonomus Germar in Canada. This species is a pest of plants in Rosaceae Jussieu, including economically important berries such as strawberries (Fragaria Linnaeus) and raspberries (Rubus idaeus Linnaeus), and of native berries of importance to Indigenous peoples in Canada. Female weevils oviposit eggs inside developing flower buds and sever flower stalks, facilitating larval development inside damaged buds and thus reducing fruit yields. Surveys to confirm the presence of A. rubi conducted in 2020 found the weevil to be well established in cultivated and wild hosts throughout the Greater Vancouver area and Fraser Valley, British Columbia. At least one species of parasitoid wasp in the genus Pteromalus Swederus (Hymenoptera: Pteromalidae) has been found in association with A. rubi in the province. Future investigations are required to understand the biology of A. rubi in its new range, assess its impact on berries, and develop management strategies.

Composition of Strawberry Floral Volatiles and their Effects on Behavior of Strawberry Blossom Weevil, Anthonomus rubi

The strawberry blossom weevil (SBW), Anthonomus rubi, is a major pest in strawberry fields throughout Europe. Traps baited with aggregation pheromone are used for pest monitoring. However, a more effective lure is needed. For a number of pests, it has been shown that the attractiveness of a pheromone can be enhanced by host plant volatiles. The goal of this study was to explore floral volatile blends of different strawberry species (Fragaria x ananassa and Fragaria vesca) to identify compounds that might be used to improve the attractiveness of existing lures for SBW. Floral emissions of F. x a. varieties Sonata, Beltran, Korona, and of F. vesca, were collected by both solid-phase microextraction (SPME) and dynamic headspace sampling on Tenax. Analysis by gas chromatography/mass spectrometry showed the floral volatiles of F. x ananassa. and F. vesca were dominated by aromatic compounds and terpenoids, with 4-methoxybenzaldehyde (p-anisaldehyde) and α-muurolene the major compounds produced by the two species, respectively. Multi-dimensional scaling analyses separated the blends of the two species and explained differences between F. vesca genotypes and, to some degree, variation between F. x ananassa varieties In two-choice behavioral tests, SBW preferred odors of flowering strawberry plants to those of non-flowering plants, but weevils did not discriminate between odors from F. x ananassa and F. vesca flowering plants. Adding blends of six synthetic flower volatiles to non-flowering plants of both species increased the preference of SBW for these over the plants alone. When added individually to non-flowering plants, none of the components increased the preference of SBW, indicating a synergistic effect. However, SBW responded to 1,4-dimethoxybenzene, a major component of volatiles from F. viridis, previously found to synergize the attractiveness of the SBW aggregation pheromone in field studies.

Reproduction of entomopathogenic nematodes of the genera Steinernema Travassos, 1927 (Rhabditida: Steienernematidae) within strawberry blossom weevil larvae Anthonomus rubi Herbst, 1795 (Coleoptera: Curculionidae)

Studies have been conducted on the contamination in the laboratory of larvae of raspberry-straw weevil (Anthonomus rubi Herbst, 1795) with two isolates of entomopathogenic nematodes (ETNs) of the genus Steinernema Travassos, 1927, vchecked the possibility of their reproduction under these conditions, and features of quantitative performance indicators. On the basis of the obtained data, it was established that, regardless of the type of isolate of the EPN, all experimental A. rubi larvae died on the 3rd day after infection, and the yield of larvae nematodes from the dead insects began on day 10—12 and lasted 42—44 days. During this period, on average, from one of the affected specimens of raspberry-straw weevil, from 26965 to 29168 larvae of the EPN was allocated. The total number of larvae of EPN obtained in the infection of 14 larvae of weevil of raspberry-strawberry was 392929 individuals. The migration of newly-formed individuals of the EPN was uneven, the bulk of the larvae (61—66.2%) is released during the second decade of the month, the rest — 24.5%—31.2% in the third decade. In the first and last decades the larvae are significantly less (3.5—5.8%).