At the edge of a species range, plants may experience myriad microenvironmental gradients, which may differ and impose strong yet complex selective regimes. We explore these issues using the model organism Arabidopsis thaliana, a native of Europe that has naturalized in North America, which we planted in a common garden field plot in Knoxville, Tennessee and observed across two biotic gradients. We found evidence that directional selection favors increased plant size, consistent with hypotheses of plant responses to novel environments. However, selection differed among plants with fungus gnat larvae damage, aphid damage, and plants that escaped herbivory, evidence that the selective landscape is variable and complex even for quasi-natural field plots. We did not uncover evidence for resistance; however, our results suggest that tolerance of A. thaliana may play an important role for population establishment and persistence in the presence of herbivores in a novel environment. Our findings highlight the variation in one segment of the biotic selective landscape of field environments, as well as the importance of biotic interactions in shaping the success of recently established populations that may be a critical component of post-invasion evolution.