Data from: Geographic distribution of terpenoid chemotypes in Tanacetum vulgare mediates tansy aphid occurrence but not abundance

Intraspecific variation of specialized metabolites in plants, such as
terpenoids, are used to determine chemotypes. Tansy (Tanacetum vulgare L.)
exhibits diverse terpenoid profiles that affect insect communities.
However, it is not fully known whether patterns of their chemical
composition and associated insects vary beyond the community scale. Here,
we investigated the geographic distribution of mono- and sesquiterpenoid
chemotypes in tansy leaves and their relationships with specific insect
communities across Germany. We sampled tansy leaves from ten plants with
and five plants without aphids in each of 26 sites along a north-south and
west-east transect in Germany. Hexane-extracted metabolites from leaf
tissues were analyzed by gas chromatography-mass spectrometry (GC-MS).
Plant morphological traits, aphid occurrence and abundance, and occurrence
of ants were recorded locally. The effect of plant chemotype, plant
morphological parameters, and abiotic site parameters such as soil types,
temperature and precipitation on insect occurrences were analyzed. Plants
clustered into four monoterpenoid and four sesquiterpenoid chemotype
classes. Monoterpene classes differed in their latitudinal distribution,
whereas sesquiterpenes were more evenly distributed across the transect.
Aphid and ant occurrence was influenced by monoterpenoids. Plants of
monoterpenoid class 1 were colonized by aphids and ants significantly more
often than expected by chance, whereas in other classes there were no
significant differences. Aphid abundance was affected by soil type, and
average annual temperature positively correlated with the occurrence of
ants. We found significant geographic patterns in the distribution of
tansy chemodiversity and show that monoterpenoids affect aphid and ant
occurrence, while the soil type can influence aphid abundance. We show
that geographic variation in plant chemistry influences insect community
assembly on tansy plants.