This study addresses how landscape structure affects the movements and distribution of a delphacid planthopper in a spatially fragmented habitat. We examined the effects of background matrices (non-host grass, saltwort, mud flat) on the dispersal of the planthopper, Prokelisia crocea, that is distributed among patches of cordgrass, Spartina pectinata, in tall-grass prairies of the Midwestern United States. We conducted a sweep-net census of planthopper density within cordgrass patches that were bordered by one of two types of background matrix: open mud flats or non-host grasses. We found significantly increased density at patch edges as compared to patch interiors; however, this edge effect was only present in cordgrass patches bordered by open mud flats. An experiment addressed whether the matrix type surrounding cordgrass patches influenced emigration rates. Flourescent-marked planthoppers were released on experimental cordgrass patches placed in four types of background matrix. Emigration rates were 1.7 times higher when the background matrix consisted of either non-host grass (Poa spp.) or cordgrass (a control), than when the matrix consisted of saltwort or mud flat. We conclude that the degree to which patch edge acts as a barrier to movement depends on the background matrices and this influences the planthopper’s within-patch distribution. Invasive grasses (such as brome) that are encroaching into the system may increase the connectivity among patches, therefore significantly changing planthopper population dynamics.
Species 1: Homoptera Delphacidae Prokelisia crocea
Keywords: landscape, dispersal
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