Chemodiversity affects preference for Tanacetum vulgare chemotypes in two aphid species

Plants of the same species can strongly differ in their specialized metabolite profiles, which can affect insect presence and abundance in the field. However, how specialized chemistry shapes plant attractiveness to herbivorous insects is not fully understood. Here, we used common tansy (Tanacetum vulgare L., Asteraceae) – a perennial plant that is highly diverse in terpenoid composition and is known to have variable chemotypes – to test whether 1) plants with different chemotype profiles differ in attractiveness to two specialist aphid species, Macrosiphoniella tanacetaria and Uroleucon tanaceti, in pairwise choice assays; 2) the diversity of the terpenoid blend affects plant attractiveness to aphids; 3) how plant chemical traits relate to plant morphological traits and which traits best explain aphid preference. We found that M. tanacetaria preferred two out of five chemotypes, dominated by α-thujone/β-thujone and β-trans-chrysanthenyl acetate, while avoiding a chemotype dominated by ..., Leaf samples of tanacetum vulgare were collected and plants were chemotyped based on their terpenoid profiles, using hexane extractions and comparing retention indices and mass spectra to available synthetic reference compounds from the library entries of the National Institute of Standards and Technology (NIST) 2014, Pherobase and mass spectra reported in Adams (2007; Adams, R. P. (2007). Identification of Essential Oil Composition by Gas Chromatography/Mass Spectrometry, 4th Edn. Carol Stream, IL: Allured Publishing Corporation). Plant terpenoid profiles were then clustered using unsupervised hierarchical k-means clustering.
Plants from five chemotypes were propagated. In choice assays one aphid was placed into a petri dish containing a leaf from two different chemtoypes each. After two and five hours the observed aphid preference was recorded.
All statistical analyzes were performed in R, using the \"survival\", \"vegan\" and \"RcmdrMisc\" package., , # Data from: Chemodiversity affects preference for Tanacetum vulgare chemotypes in two aphid species

## Description of the data and file structure

We collected data on aphid choice via observations. We tested two aphid species (**Aphid_Species**). One aphid individual was given a choice between leaves from two chemotypes, placed on the left side of the petri dish (**Chemotype1_SideA**) or the right (**Chemotype2_SideB**). Every chemotype comprised three daughters (**Daughter1_SideA**; **Daughter2_SideB**). As we used 5 chemotypes, ten combinations (**Combination_of_Chemotypes**) were possible. For *Macrosiphoniella tanacetaria*, we tested each combination 23 times (**Replication_of Combinations_tested**), while for *Uroleucon tanaceti* combinations were replicated 13 times. After two and five hours the side of the leave with the aphid on, was noted (**Choice_after_2h**; **Choice_after_5h**) and translated into the chemotype (**Selected_Chemotype_2h**; **Selected_Chemotype_5h**) and ...