Holocyclic life cycle

Definition

A life cycle in aphids (Aphididae) that includes both a sexual phase with egg production and multiple parthenogenetic (asexual) generations, typically cycling between a primary woody host and secondary herbaceous hosts across seasons. The sexual phase produces cold-resistant eggs that overwinter, ensuring genetic recombination and survival through harsh conditions.

Etymology

Greek holo- (whole, complete) + kyklos (circle, cycle); coined to contrast with truncated (anholocyclic) cycles lacking the sexual phase.

Example

The green peach aphid Myzus persicae exhibits a holocyclic life cycle in temperate regions: eggs hatch on peach trees in spring, fundatrices produce parthenogenetic stem mothers that migrate to herbaceous summer hosts, and in autumn, winged males and oviparae return to peach where sexual reproduction produces overwintering eggs.

Synonyms

• complete life cycle
• heteroecious holocycle

Related Terms

• Anholocyclic life cycle
• heteroecy
• autoecy
• fundatrix
• ovipara
• Parthenogenesis
• host alternation
• Polyphenism

Usage Notes

The term applies specifically to aphids; many aphid populations in mild climates or greenhouses have lost the sexual phase and become anholocyclic. 'Holocyclic' implies host alternation in most species, though some autoecious aphids (remaining on one host) also retain sexual reproduction. The distinction between holocyclic and anholocyclic is ecologically significant for predicting overwintering success, population genetics, and pest management strategies.