Conventional thinking says the answer is in the numbers of both insects and times they enter, but new findings to be published in the Proceedings of the National Academy of Sciences suggest that opportunity alone is no guarantee of a successful invasion.
Of 232 species of ants that entered U.S. ports uninvited from 1927 to 1985, 28 species (12 percent) now occur as established non-native species, scientists from three universities report. Their paper appears this week online in the PNAS Early Edition. An important factor in the ants success, they say, was nesting preferences.
"There are a huge number of species being moved around that don't become established, so opportunity alone isnt sufficient," said Andrew V. Suarez, a professor in the entomology and animal biology departments at the University of Illinois at Urbana-Champaign. "This makes sense, because many of these species have specific biological characteristics that prevent them from becoming established in a new environment."
Ants that stuck around were either ground-nesting species or arboreal species that did not depend solely on specific types of trees common to their native lands, Suarez said. "This kind of information is important, because it's going to help us identify the characteristics that may promote the success of non-native organisms. Eventually, we can use this information to keep the new wave of invaders from becoming established."
Suarez primarily studies Argentine ants, an aggressive species that has caused problems in Southern California since arriving in 1905 and successfully establishing large colonies that overwhelm native food webs.
His work led him to the Smithsonian Institution's National Museum of Natural History, where he found a gold mine of untapped ant history. In numerous containers
Contact: Jim Barlow, Life Sciences Editor
University of Illinois at Urbana-Champaign