Arthropod communities on native and non-native early successional plants

Early successional ruderal plants in North America include numerous native and non-native species, and both are abundant in disturbed areas. The increasing presence of non-native plants may negatively impact a critical component of food web function if these species support fewer or a less diverse arthropod fauna than the native plant species that they displace. We compared arthropod biomass and richness on six species of common early successional native plants and six species of non-native plants, planted in replicated native and non-native plots in a farm field. Samples were taken twice each year for two years. In most arthropod samples total biomass, abundance, and species richness were substantially higher on the native plants than on the non-native plants. Native plants produced as much as five times more total arthropod biomass and up to seven times more species per 100 g of dry leaf biomass than non-native plants.  Both herbivores and natural enemies (predators and parasitoids) predominated on native plants when analyzed separately. Generalist insects comprised 93% of herbivore species collected.  Nonmetric multidimensional scaling showed clear differences between the insect communities found on the native and non-native plants. These results support a growing body of evidence suggesting that non-native plants support fewer arthropods than native plants, and therefore contribute to reduced food resources for higher trophic levels.