ST. OMER, LUCY. Department of Biological Sciences, San Jose State University, San Jose, CA 95192. - Parasitic choice of host individuals in a seemingly homogeneous environment.
It has been postulated that differences in environmental conditions
among hosts species existing at microsites influence spatial
patterning of plant parasites. Distribution pattern among halophytic
host species for the parasite, Cuscuta salina, is patchy at the Palo
Alto saltmarsh in Northern California. The preferred host, among
several halophytic host species, is Salicornia virginica. To test this
hypothesis studies of the biotic and abiotic environments of host
plant species were examined. Marked spatial heterogeneity was present
within the biotic and abiotic environments of the three infested host
species examined. Significantly different among the three host species
were succulence of shoot tissues, salt accumulations on shoot surfaces
as well as water contents of associated soils. Ionic accumulations in
plant tissues also indicated spatial differences for specific ions.
However, examinations of soil nutrients in soils associated with
parasitic infestations as compared with soils of non-infested areas
failed to indicate any spatial differences between the two soil types.
The data presented here in this study suggest that parasitic host
preference may indeed be influenced by spatial heterogeneity among
host plant species and their associated soil environments.
Key words: parasite, plant and soil nutrients, plant host species, saltmarsh