Comparison of the Assemblages of Sap-Feeding Insects (Homoptera-Hemiptera) Inhabiting Two Structurally Different Salt Marsh Grasses in the Genus Spartina 1

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Abstract
The vegetation of New Jersey tidal salt marshes is composed primarily of 2 grasses; Spartina patens , which occupies a narrow elevational zone of high marsh and Spartina alterniflora , an intertidal species. S. patens forms a dense, persistent, thatch, while S. alterniflora produces only a loose lattice of litter which rapidly decomposes. A comparison between the guilds of sap-feeding insects (for the most part, Delphacidae, Cicadellidae, Issidae, and Miridae) inhabiting these grasses reveals S. patens housing a much more diverse assemblage of herbivores than S. alterniflora. S. alterniflora -inhabiting species are exclusively bi- or trivoltine, while on S. patens , sap-feeders possess a greater variety of life history types and show a specialized trend toward univoltinism. Removal of only the dead thatch portion of S. patens results in reduced species diversity and evenness of sap-feeders on the living grass system. Trivoltine species, which normally inhabit the upper strata of S. patens , increase their populations on dethatched grass compared to the unaltered grass system. Both empirical and experimental evidence suggests that the complex microstructure and thatch of S. patens provide a more heterogeneous and protective resource which supports a more diverse and specialized fauna of sap-feeders than S. alterniflora .