Milkweed beetle

Definition

Any of several cerambycid beetles (family Cerambycidae) in the genera Tetraopes and Chrysochus that are obligate specialists on milkweed plants (Asclepias spp.), sequestering cardiac glycosides from their host for chemical defense. The term most commonly denotes the red milkweed beetle, Tetraopes tetrophthalmus, a conspicuous North American species with bright red elytra marked by black spots and antennae inserted within the eyes—a diagnostic trait of the genus.

Etymology

From the obligate association with milkweed host plants (genus Asclepias).

Example

The red milkweed beetle, Tetraopes tetrophthalmus, is frequently used in chemical ecology studies because its sequestration of cardiac glycosides mirrors the defensive strategy of monarch butterflies feeding on the same host plant.

Synonyms

• red milkweed beetle (Tetraopes tetrophthalmus)
• blue milkweed beetle (Chrysochus cobaltinus)

Related Terms

• Cerambycidae
• Tetraopes
• Asclepias
• cardiac glycoside
• Sequestration
• host specialization
• aposematism

Usage Notes

While "milkweed beetle" most often refers to Tetraopes tetrophthalmus, the term also applies to related Tetraopes species and to Chrysochus cobaltinus (the blue milkweed beetle), a chrysomeline leaf beetle in a different subfamily. The two genera represent independent evolutionary origins of milkweed specialization. Specialists distinguish them by family: Tetraopes in Cerambycidae (longhorn beetles) versus Chrysochus in Chrysomelidae (leaf beetles).