The genus Agrilus: An example of evolutionary, ecological, and economic megadiversity

The buprestid beetle genus Agrilus is one of the most species-rich genera in the world with nearly 3000 valid described species and subspecies, and hundreds and perhaps thousands of undescribed species. It is distributed throughout the world but is especially rich in the Western Hemisphere. In the United States there are nearly 200 native species and an additional 9-10 non-native species. Ecologically, most are apparently subcortical cambium miners in woody plants, but species are known to bore in roots or soft stems or form galls on woody or non-woody species. Most appear to be narrowly host-specific, which probably contributes to their diversity. The genus Agrilus has recently become very conspicuous economically because of the invasive and destructive emerald ash borer, Agrilus planipennis, but seven other economically important native and non-native species have been given common names by the ESA. Most species appear to have small populations, and are therefore economically negligible, and one species (Agrilus hyperici) has been introduced as a beneficial biocontrol agent.