A new method for evaluating host preference ofCuscutaspecies

Abstract

A new method is presented for evaluating the host preference of dodders. This technique takes account of the frequency and intensity of infestations, the proportion of the resource use and availability, the resource distribution as well as the defence mechanisms of the hosts. The process categorises not only the host species but each infestation, respectively, and establishes an order of preference among the host species. This method considers also the fact that the preference status of a host species may considerably vary under different circumstances (under different species environments and/or in different habitats). The method was tested on Cuscuta europaea at 75 localities in Hungary. During the study 1,189 plant-parasite relationships were examined and categorised. This dodder was found to parasitise almost every plant, which came into contact with it in the natural habitats, however, the intensity of infestations greatly varied among the host species. A list of the most preferred, most avoided and the most frequently parasitised accessory host species was prepared for C. europaea. The results revealed that plant species of the nitrogen-poor habitats and species from Poaceae could not be preferred hosts for this dodder.