Biology subjects

Neuhaus-Harr, A.

Publications and source records attributed to Neuhaus-Harr, A..

2 recordsLinked to original sources

bioRxiv2023

Geographic distribution of terpenoid chemotypes in Tanacetum vulgare mediates tansy aphid occurrence and abundance

AimIntraspecific variations 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 on a large scale. Here, we investigated the geographic distribution of mono- and sesquiterpenoid chemotypes in tansy leaves and the effects of these chemotypes on colonization by insect communities across Germany. MethodsWe sampled tansy leaves from 26 sites along a north-south and west-east transect in Germany. Leaves from ten plants with and five plants without aphids was collected from each site. Hexane-extracted metabolites from leaf tissues were analysed by gas chromatography-mass spectrometry (GC-MS). Plant morphological traits, aphid occurrence and abundance, and occurrence of ants were recorded. The effect of plant chemotype, plant morphological parameters, and site parameters such as temperature and precipitation on insect occurrences were analysed. ResultsPlants 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 were influenced by monoterpenoids and specific traits. Plants of monoterpenoid class 1 were colonized by Metopeurum fuscoviride and ants significantly more often than expected by chance compared to plants from monoterpenoid class 4. Aphid abundance was negatively affected by host plant height, and increasing average annual temperature positively influenced the occurrence of ants. ConclusionWe found significant geographic differences in the chemodiversity of tansy and show that monoterpenoids affect aphid and ant occurrence, while host plant height can influence aphid abundance. We show that geographic variation in plant chemistry and morphology influences insect communities assemblage on tansy plants.

ecology↗

bioRxiv2023

Chemodiversity affects preference for Tanacetum vulgare chemotypes in two aphid species

Plants of the same species often strongly differ in morphological traits, as well as in the abundance and composition of specialized metabolite profiles. Specialized metabolites can act as mediators of interactions on plants, and 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 specialized aphids, Macrosiphoniella tanacetaria and Uroleucon tanaceti, in pairwise choice assays. Furthermore, we tested whether 2) the diversity of the terpenoid blend affects aphid attractiveness. Lastly, we tested how 3) plant chemical traits relate to plant morphological traits, and which best explain aphid preference. We found that M. tanacetaria preferred two out of five chemotypes, dominated by -thujone/{beta}-thujone and {beta}-trans-chrysanthenyl acetate, respectively, while avoiding a chemotype dominated by -pinene/sabinene. U. tanaceti showed no clear preference towards chemotypes, but when given the choice between chemotypes dominated by -thujone/{beta}-thujone and by -pinene/sabinene, they preferred the former. Importantly, plant attractiveness to aphids tended to be negatively correlated with chemodiversity, i.e., the number of terpenoid compounds, in M. tanacetaria, but not in U. tanaceti. Interestingly, the approximate concentration and number of terpenoid compounds was generally higher in larger and bushier plants. Hence, we did not observe a trade-off between plant growth and defence. We conclude that plant chemical composition affects plant attractiveness to aphids and hence may contribute to variation in natural aphid colonization patterns on plants of the same species.

ecology↗