The interplay of multiple spatial scales influences plant–herbivore interactions

We examined the colonization potential of the chrysanthemum lace bug, Corythucha marmorata, on populations of its host plant, tall goldenrod, Solidago altissima L. In a common garden experiment, we found variation in plant resistance within and among eight USA and four Japanese populations of S. altissima to herbivory by the Duluth, MN, USA population of C. marmorata. Duluth lace bugs significantly differed in their preference for and performance among plant populations and genotypes within populations. Colonization of plant populations was facilitated because Duluth lace bug survival was high on at least one plant genotype in each population. The high genotypic variation in resistance within the Duluth goldenrod population is consistent with the hypothesis that has led to the evolution of the lace bug's ability to deal with a wide range of plant resistance that would improve colonization potential. Because lace bugs are adapted to feeding on senescing tissues with high levels of soluble nitrogen, we hypothesized that preference and performance would be positively related to leaf senescence and plant nitrogen concentrations. We partially supported the prediction that plant leaf nitrogen influenced lace bug preference and performance, as some plant populations with lower total leaf nitrogen had lower lace bug performance. Thus, leaf senescence affected lace bug performance, but there was a complex interaction between plant genotype and the amount of leaf senescence. Our results suggest that tall goldenrod resistance to lace bugs results from adaptation to large- and fine-scale environmental heterogeneity.