TRADE-OFF BETWEEN REPRODUCTION AND LENGTH OF ADULT LIFE IN MALES AND MATING FEMALES OF APHIDS

Males of the willow-carrot aphid, Cavariella aegopodii (Scopoli) (Ster norrhyncha: Aphididae), that were caged with five or more females had shorter adult lives than those caged with one or no females. Similarly mated females had a shorter adult life than unmated females. The diff erence in lifespan appears to result from a change in the time of onse t of senescence rather than a change in the rate of senescence. Contra ry to what is observed in most other animals unmated males of the will ow-carrot aphid had much longer lives than unmated females. The asymme try of the sexes in terms of the factors that affect their fitnesses a nd the deadline to further egg maturation imposed by leaf fall possibl y accounts for why the males of this aphid are potentially the longer lived sex.