Sphaeroderma testaceum
(Fabricius, 1775)
artichoke beetle
Sphaeroderma testaceum, commonly known as the artichoke , is a in the . It is to Europe, North Africa, and Israel, and has been to Atlantic Canada. are active from late spring through early autumn and feed on leaves of thistles and related plants. The is notable as a pest of artichokes and other cultivated thistles.
Pronunciation
How to pronounce Sphaeroderma testaceum: /sfɛːroʊˈdɛrmə tɛsˈtæsɪəm/
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Identification
Distinguished from the very similar Sphaeroderma rubidum by smaller body size and quadrate (more square-shaped) . Reliable separation requires examination of . The combination of light -orange coloration, wide with closely set , and with two notches and coarse puncturation aids field recognition.
Images
Appearance
Small measuring 3.5–4 mm in length. Body shiny light -orange. wide with large . positioned close together between eyes. convex, slightly elongate, and quadrate in shape. with coarse puncturation basally, prominent corners, a well-defined groove, and two notches. Hind enlarged.
Habitat
Wasteland, woodland edges, roadsides, and other areas where plants (thistles and related Asteraceae) occur. Presence is strongly tied to availability of larval and rather than specific vegetation structure.
Distribution
to most of Europe, North Africa, and Israel. in Atlantic Canada (, established).
Seasonality
active from May/June to September. New adults emerge in May following spring .
Diet
Both and feed on leaves of thistles and related plants: Carduus, Carlina, Cirsium, Onopordum, Cynara (artichokes), Centaurea nigra (Common Knapweed), and Serratula . In Canada, has been recorded on Cirsium arvense.
Host Associations
- Carduus - and feed on leaves
- Carlina - and feed on leaves
- Cirsium - and feed on leaves; includes C. arvense in Canada
- Onopordum - and feed on leaves
- Cynara - and feed on leaves; includes cultivated artichokes
- Centaurea nigra - and feed on leaves; Common Knapweed
- Serratula - and feed on leaves
Life Cycle
Overwinters as third (final) , sometimes as . occurs in spring. New adults emerge in May. Adults present through September. Larval development occurs on leaves.
Ecological Role
specializing on thistles and related Asteraceae. May contribute to of weedy thistles, though also damages cultivated artichokes.
Human Relevance
Agricultural pest of artichokes (Cynara ). derives from this association. to Atlantic Canada, where it has been observed on Cirsium arvense.
Similar Taxa
- Sphaeroderma rubidumExtremely similar external ; distinguished reliably only by examination, though S. testaceum averages smaller with more quadrate
More Details
Nomenclatural note
GBIF lists this as a synonym of Pistosia testacea, though NCBI and most sources maintain Sphaeroderma testaceum as the accepted name. The basionym is Altica testacea Fabricius, 1775.
North American introduction
The is ( and established) in Atlantic Canada, with records on Cirsium arvense, but does not appear to have spread widely in North America based on available distribution data.