Host specificity of Cuscuta species: is it a cause or a consequence of the habitat preference?

Aims

The genus Cuscuta comprises nearly 200 parasitic plant species. Sympatric Cuscuta species are considered to occur in different habitat types. We investigated the reasons for the observed habitat preference addressing the following questions: Can host specificity explain the habitat preference? Can soil characteristics influence habitat preference?

Methods

We sampled 543 vegetation plots and collected 56 soil samples from the habitats of C. europaea, C. campestris, C. epithymum, C. lupuliformis, and C. australis in Hungary. The percent cover, maximum height, and parasitism status of each species were recorded in every plot. The species composition and soil parameters of the habitats were compared using multivariate data analysis.

Results

Habitats of the examined parasites significantly differed from each other based on species number and composition, as well as vegetation cover and height. However, species compositions in the habitat of the same Cuscuta species also varied considerably in different localities. We also found that the host range of the same Cuscuta species differed greatly in different locations. None of the dodders had any essential host species without which they could not survive and develop. Additionally, the habitats of the examined Cuscuta species significantly differed from each other based on soil conditions.

Conclusion

Host specificity alone does not explain the strong preference of these host generalist parasites for certain habitats. Rather, the complex system of biotic and abiotic factors, including the mineral composition of the soil, determines the habitats of dodders.