Effect of plant chemical variation and mutualistic ants on the local population genetic structure of an aphid herbivore

Abstract

Plants exhibit impressive genetic and chemical diversity, not just between species but also within species, and the importance of plant intraspecific variation for structuring ecological communities is well known. When there is variation at the local population level, this can create a spatially heterogeneous habitat for specialised herbivores potentially leading to non‐random distribution of individuals across host plants. Plant variation can affect herbivores directly and indirectly via a third species, resulting in variable herbivore growth rates across different host plants. Herbivores also exhibit within‐species variation, with some genotypes better adapted to some plant variants than others. We genotyped aphids collected across 2 years from a field site containing ~200 patchily distributed host plants that exhibit high chemical diversity. The distribution of aphid genotypes, their ant mutualists, and other predators was assessed across the plants. We present evidence that the local distribution of aphid (Metopeurum fuscoviride) genotypes across host‐plant individuals is associated with variation in the plant volatiles (chemotypes) and non‐volatile metabolites (metabotypes) of their host plant tansy (Tanacetum vulgare). Furthermore, these interactions in the field were influenced by plant‐host preferences of aphid‐mutualist ants. Our results emphasise that plant intraspecific variation can structure ecological communities not only at the species level but also at the genetic level within species and that this effect can be enhanced through indirect interactions with a third species.

Chemical composition and antibacterial effect of Smyrnium olusatrum L. Fruit Essential Oil

“…Indeed, although all these countries are different, they all belong to the Mediterranean region. Moreover, the published data relating to the chemotype of aromatic plants support the influence of genotypes as well as ecotypes (light, precipitation, growing site, and nature of the soil (pH, constituents) seasonal variation), but also the age and part of plant [26][27][28][29] .…”

Generalism in Nature…The Great Misnomer: Aphids and Wasp Parasitoids as Examples

“…These ants appear to prevent other aphid species from settling on plants occupied by M. fuscoviride, perhaps even killing them [30,123], although not necessarily consuming them because of the terpenes/terpenoids [124] that they contain ( cf . [77,78] and references therein). In addition, the distribution of trichomes and sugars, organic acids and amino acids, and secondary plant antifeedants, especially terpenes/terpenoids, has recently been found to significantly influence the positioning of different tansy aphid species on and between plant chemotypes [75,77,78,79], and as such and as Jakobs & Mūller state in their 2018 paper in relation to tansy aphid feeding preference and performance [75]: “These different performance optima may cause niche differentiation and, therefore, enable co-existence.…”

“…[77,78] and references therein). In addition, the distribution of trichomes and sugars, organic acids and amino acids, and secondary plant antifeedants, especially terpenes/terpenoids, has recently been found to significantly influence the positioning of different tansy aphid species on and between plant chemotypes [75,77,78,79], and as such and as Jakobs & Mūller state in their 2018 paper in relation to tansy aphid feeding preference and performance [75]: “These different performance optima may cause niche differentiation and, therefore, enable co-existence. In conclusion, the tremendous variation in plant chemistry even within one species can affect the distribution of highly specialized aphids at various scales aphid species-specifically .” (cf.…”

“…Benedek et al [77] were the first to show that tansy aphids, M. fuscoviride , were differentially attracted to, and survived on, different genets of tansy, dependent on terpene/terpenoid chemotype (cf. also [78]). In fact, and fascinatingly, recent research by Jacobs & Mueller [75,79,80] have revealed that this fine-grained micro-ecological distribution of tansy aphids between plants also even extends within plants, where it is again governed by the intra -plant chemical profile, as well as trichrome arrays (see Discussion for further details).…”

Spectral Fingerprints Predict Functional Phenotypes of a Native Shrub

“…In this way, chemotypes serve as an important link among genotypes interacting with the environment and resultant phenotypes. For example, chemotypes influence population genetics and genetic adaptation (Zytynska et al, 2019), plant demographic rates (e.g., population structure, community, distribution; Ehlers and Thompson, 2004), phenology (e.g., greenup; Thoss et al, 2007;Welker et al, 2007;Usano-Alemany et al, 2014), and interactions with herbivores (e.g., foraging behavior and diet selection; .…”