Indirect Effects of Biological Control on Plant Diversity Vary across Sites in Montana Grasslands

Aphthona nigriscutis was introduced into Montana grassland areas infected with the invasive species Euphorbia esula L. Aphthona release resulted in a 33% to 39% Euphorbia decline after five years, but did not necessarily produce an increase in species diversity. Biocontrol introductions should therefore be accompanied by community-level effects monitoring.