Anthonomus rubi

Bedel, 1887

strawberry blossom weevil, strawberry-blossom weevil

Anthonomus rubi is a small weevil native to Europe, Asia, and North Africa that has become established in North America (first detected in British Columbia, Canada in 2019, then Washington State, USA in 2021). It is a major agricultural pest of strawberry and raspberry, with females laying single in unopened flower buds before severing the stalk, causing bud death and yield losses up to 80% in severe cases. The has been observed to exhibit prolonged activity year-round in protected systems, with recent documentation of direct fruit feeding in addition to traditional bud damage.

Anthonomus rubi by (c) Mick Talbot, some rights reserved (CC BY). Used under a CC-BY license.

Anthonomus.rubi.1 by Sarefo. Used under a CC BY-SA 4.0 license.

Anthonomus Rubi by Robert Henschel. Used under a Public domain license.

Pronunciation

How to pronounce Anthonomus rubi: //ˌænθəˈnoʊməs ˈruːbaɪ//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

distinguished from similar Anthonomus by combination of small size (2–4 mm), dull black coloration with grey , and association with Rosaceae . Distinguished from Anthonomus brunnipennis by stage ; from Anthonomus signatus (strawberry bud weevil, native to North America) by geographic origin and subtle morphological differences. Identification in British Columbia confirmed through genetic analysis.

Images

Habitat

Agricultural settings: strawberry fields, raspberry plantations, and blackberry crops; protected systems (soilless tunnels, plastic greenhouses); semi-natural adjacent to crop fields including grass cover areas and wild patches; shelters located within cropping areas and perimeter wild host plants. In invaded range (British Columbia), also found on non-crop native hosts including Salmonberry (Rubus spectabilis) and Thimbleberry (Rubus parviflorus) not present in native range.

Distribution

Native: Europe, western Asia, North Africa. : established in British Columbia, Canada (first detection 2019, Abbotsford; confirmed widespread in Greater Vancouver area and Fraser Valley by 2020) and Washington State, USA (2021).

Seasonality

Overwintered emerge April–May when temperatures reach 8–15°C; oviposition period lasts 1–2 months; larvae develop in severed buds, emerging as adults in late summer. Recent observations in Italian tunnel systems show prolonged year-round adult activity with continued bud and fruit damage through October; newly emerged adults can survive >240 days under laboratory conditions.

Diet

feed on foliage, open flower petals, and pollen of Rosaceae plants; larvae feed on pollen and developing tissue within flower buds. Documented include cultivated strawberry (Fragaria × ananassa), wild strawberry (F. vesca), raspberry (Rubus idaeus), blackberry (Rubus spp.), dog rose (Rosa canina), and ornamental roses. Recent observations confirm direct feeding on strawberry fruits at all ripening stages (green, white, pink/red), creating small deep holes. In British Columbia, also feeds on Salmonberry and Thimbleberry.

Host Associations

Fragaria × ananassa - primary cultivated cultivated strawberry, major economic impact
Fragaria vesca - wild wild strawberry
Rubus idaeus - primary cultivated raspberry
Rubus fruticosus - blackberry
Rubus spectabilis - ( range only)salmonberry, British Columbia
Rubus parviflorus - ( range only)thimbleberry, British Columbia
Rosa canina - dog rose
Rosa spp. - ornamental roses
Pteromalus spp. - at least one associated with A. rubi in British Columbia
Steinernema spp. - , laboratory studies show in A. rubi larvae

Life Cycle

(one per year) with potential for extended activity. Overwintered emerge in spring, feed on foliage and flower buds, mate, then females oviposit single in unopened flower buds and sever the peduncle. Larvae develop and pupate within withered buds. Adults emerge in late summer, feed on foliage for several weeks, then move to sites. Recent findings indicate newly emerged adults in the same year can sever buds and possess egg-laying potential, and eggs may be present in 40% of non-severed buds.

Behavior

Females exhibit distinctive stalk-severing after oviposition, partially or completely cutting the flower peduncle to facilitate larval development in the wilting bud. demonstrate strong olfactory orientation: attracted to floral volatiles of strawberry (particularly 4-methoxybenzaldehyde in F. × ananassa, α-muurolene in F. vesca), with preference for flowering over non-flowering plants. Males produce an (grandlure I, grandlure II, and lavandulol in 1:4:1 ratio) that attracts both sexes. Synergistic response to blends of synthetic floral volatiles; 1,4-dimethoxybenzene enhances pheromone trap catches. Adults move between crop and non-crop , suggesting use of alternative for maintenance.

Ecological Role

Major agricultural pest causing 5–90% bud damage and up to 60% yield loss in strawberry; damage increases harvesting and sorting labor. In invaded range (British Columbia), threatens native berry important to peoples. Serves as for (Pteromalus spp.) and (Steinernema spp.). Potential role in supporting of natural enemies in agricultural landscapes.

Human Relevance

Significant economic pest of soft fruit production in Europe and emerging threat in North America. Damage mechanisms include bud destruction (reducing fruit set) and direct fruit feeding (rendering berries unmarketable). Monitoring employs yellow sticky traps and -baited traps; mass trapping shows promise but requires optimization. Control methods include physical removal of severed buds and , use of black fabric to create lethal high temperatures, and applications (though resistance documented). strategies under development for new .

Similar Taxa

Anthonomus signatusNative North American 'strawberry bud weevil' with similar and range; distinguished by geographic distribution and subtle morphological differences
Anthonomus brunnipennisEuropean with morphological similarity; stages differ; plant is Potentilla erecta rather than Rosaceae fruit crops

More Details

Pheromone composition

Male-produced consists of three components: grandlure I, grandlure II, and lavandulol in 1:4:1 ratio. Commercial lures now incorporate 1,4-dimethoxybenzene based on demonstrated synergistic effect.

Invasion history

First North American detection in Abbotsford, British Columbia in 2019; by 2020 confirmed established throughout Greater Vancouver area and Fraser Valley. Crossed into Washington State, USA by 2021. of introduction unknown but likely associated with plant material movement.

Recent behavioral shifts

Observations from 2017–2020 in Italian tunnel systems document: (1) prolonged activity year-round rather than summer-winter , (2) direct fruit feeding creating deep holes at all ripening stages, (3) newly emerged adults with reproductive potential in same year of , and (4) survival exceeding 240 days under laboratory conditions. These findings contrast with traditional literature and may represent phenotypic plasticity in protected environments.