Genetically based population variation in aphid association with ants and predators

A species’ genotype can have extended consequences for the structure of the surrounding community, but few studies have investigated the extended consequences of genetic variation in animals. Accordingly, I examined the importance of genetically based variation among five populations of the ant-tended aphid Aphis asclepiadis for its interactions with both ants and predators. In a common environment, aphid source population accounted for 23 and 17% of the variation in the occurrence of ants and predators, respectively. Ant exclusion increased predator abundance, accounting for 25% of variation, but there was no detectable influence of ants on aphid abundance. There was an indication that aphid source populations varied in honeydew quality, but this was uncorrelated with rates of ant attendance. This study provides the first evidence for genetic variation in aphids for attractiveness to ants, and underscores the important link between intra-specific genetic variation in aphids and the processes governing arthropod community structure.