Body colour and genetic variation in winged morph production in the pea aphid

Aphids (Homoptera: Aphidoidea) produce a number of different phenotypes in their life-cycle, among which are winged (alate) and wingless (apterous) mo rphs. Lowe & Taylor (1964) and Sutherland (1969a, b) were the first to sugg est that aphid clones differ in their propensity to produce the winged morp h and that in the pea aphid (Acyrthosiphon pisum Harris), this propensity i s linked to the colour of the phenotype. We tested for the occurrence of ge netic variation in winged morph production by rearing individuals from red and green clones of pea aphid under wing-inducing (crowding) and control co nditions, and scored the phenotypes of their offspring. Clones differed sig nificantly in alate production and red clones produced on average a higher proportion of winged morphs than green clones. Importantly, however, there was considerable variation between clones of the same colour. Broad-sense h eritabilities of winged morph production were 0.69 (crowding treatment) and 0.63 (control). Clones also differed in the number of offspring they produ ced. When exposed to the crowding stimulus, aphids deferred offspring produ ction, resulting in a higher number of offspring produced in the crowding t reatment than in the control.