Genetically based population variation in aphid association with ants and predators

Abstract

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.

Ant–aphid interactions on Asclepias syriaca are mediated by plant genotype and caterpillar damage

“…In contrast, Formica does not tend or prey upon Myzocallis , but is positively correlated with Myzocallis abundance as it collectes its honeydew from leaf surfaces (Mooney and Agrawal 2008). Formica in turn reduces Myzocallis abundance (Mooney andAgrawal 2008, Smith et al 2008), likely due to reduced Myzocallis fecundity or increased dispersal. While it is seemingly paradoxical that Formica positively correlates with, but decreases Myzocallis abundance, these opposing patterns are parallel to other commonly observed density-dependent associations between consumers and resources (e.g.…”

Plant chemical defense indirectly mediates aphid performance via interactions with tending ants

“…However, honeydew composition of tended and untended aphid species often differs significantly (Völkl et al. , Fischer and Shingleton , Mooney ), suggesting evolutionary adaptations by tended aphids to better attract ants and maintain mutualistic services. Both quantity and quality of honeydew are in part under the control of tended aphids (Takeda et al.…”

“…Both quantity and quality of honeydew are in part under the control of tended aphids (Takeda et al 1982, Fischer andShingleton 2001) and can mediate the degree of mutualistic behavior by ants (Völkl et al 1999). However, there are likely R eports physiological limits to this plasticity, and honeydew composition can have a fixed genetic component among individuals of a tended species (Mooney 2011). The composition of plant phloem, likely under genetic and environmental control, is therefore a key extrinsic factor for the determination of honeydew quality (Fischer and Shingleton 2001), and may have significant impacts on ant-aphid mutualisms.…”

“…The aphid Aphis asclepiadis Fitch feeds on the common milkweed Asclepias syriaca L. and is virtually always tended by ants in the field, with generally beneficial effects of tending on aphid performance (Mooney andAgrawal 2008, Smith et al 2008). However, natural variation among plant genotypes may alter this interaction from mutualistic to antagonistic .…”

Community Genetic and Competition Effects in a Model Pea Aphid System

“…In an experiment testing the effect of genetic diversity within the aphid (A. pisum) on interspecific competition (with M. viciae), Hazell et al (2006) showed that aphid genotype could change the outcome of interspecific competition. This highlights further the importance that within-species genetic variation can have on the outcome of species interactions (Mooney, 2011). Had we incorporated genetic variation of the interspecific competitors in our study (we only used a single genotype of the interspecific competitors), we may well have revealed additional complexity as a result of interactions among genotypes of all three species.…”