Pea aphid

Definition

A small, soft-bodied aphid species (Acyrthosiphon pisum, family Aphididae) that feeds phloem sap from leguminous plants including pea, clover, alfalfa, and broad bean. A major agricultural pest worldwide and a premier model organism for insect genomics, developmental biology, and the study of polyphenism, symbiosis with Buchnera bacteria, and host-plant specialization.

Etymology

From the host plant 'pea' + 'aphid', the common name for small sap-sucking insects in family Aphididae; scientific name Acyrthosiphon from Greek elements referring to 'unpointed siphon' (the cornicles), pisum from Latin for pea.

Example

Pea aphid populations exhibit remarkable polyphenism: unwinged females reproduce parthenogenetically on host plants during favorable conditions, while winged morphs develop for dispersal when crowding or plant quality declines.

Synonyms

• Acyrthosiphon pisum
• green pea aphid

Related Terms

• aphid
• Acyrthosiphon
• Aphididae
• Buchnera
• Polyphenism
• Parthenogenesis
• phloem feeder
• Hemiptera
• model organism
• crop pest

Usage Notes

The common name 'pea aphid' properly refers only to Acyrthosiphon pisum, though 'green peach aphid' (Myzus persicae) is a distinct and similarly important pest. In laboratory contexts, 'pea aphid' almost always indicates the sequenced clone LSR1 or derivatives. The species comprises multiple host races specialized on particular legumes, sometimes treated informally as 'pea' and 'clover' biotypes.