Image: A ground-nesting Argentine ant (Linepithema humile) feeds on the honeydew of a Brown Soft Scale (Coccus hesperidum), a pest of citrus, that is on a tangerine tree. The ant is an additional pest to citrus by spreading the scale and defending the scale from biological controls such as parasitic flies and wasps. This ant species arrived in Louisiana in 1891 and California in 1907. Photo courtesy Alex Wild (myrmecos.net)
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 isn’t 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.
Image: Species shown in the top three rows are among those identified in the USDA samples that have successfully established themselves in the United States. The five species in the bottom row were in the samples, but have not yet been successful in the U.S. Photo courtesy of Brian Fisher, California Academy of Sciencesr
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 were mostly unidentified ants that the U.S. Department of Agriculture had captured at quarantine sites around the country. Each container was labeled with a port of departure and a port of entry. The ants had been collected from plants or plant material, mostly tropical in origin, before any of the ants had a chance to establish themselves.
Suarez, then a postdoctoral student, and colleague Phillip S. Ward, a professor at the University of California at Davis, spent years identifying 232 different species from 58 genera and 12 subfamilies from the 394 records stored at the museum. Suarez and Ward then teamed with David A. Holway, a professor of biology at the University of California at San Diego, to analyze their discoveries.
Of the 232 species identified, the researchers were able to determine definitive data on nest-site preferences of 156 species. Using multiple-logistic regression, the scientists tested the influence of how many times in the records particular species were imported, nesting behavior and their interaction on the success or failure of successful establishment.
Slightly more than half of 156 species they identified were tree-nesting ants, and, only 14 percent of these arboreal ants (four species) became established in the U.S., probably because they weren’t dependent on specific kinds of trees, Suarez said.
“As a group of introduced species, invasive ants are clearly important,” Holway said. “Five species of ants, for example, are included in the top 100 worst invasive organisms by the IUCN (The World Conservation Union).”
This National Science Foundation-funded study provides a rare look at data on “failed introductions for an important group of unintentionally introduced insects,” he said. “To date, few studies on introduced insects, other than those intentionally introduced for biological control, have addressed the issue of failed introductions.”
The three researchers also noted the vital role that museums play in advancing scientific inquiry, and they urged a new quarantine program to curate intercepted material.
Source: University of Illinois at Urbana-Champaign
Related stories:
Fear of predators may be a bigger killer than the predators themselves
(PhysOrg.com) -- When biologists consider the effects that predators have on their prey, they shouldn’t just count the number of individuals consumed. According to a University of Rhode Island ecologist, they must also examine the effects of fear.
Genes and nutrition influence caste in unusual species of harvester ant
Researchers trying to determine whether nature or nurture determines an ant's status in the colony have found a surprising answer. Both.
A new species of predatory bagworm from Panama's tropical forest
University of Panama and Smithsonian researchers report the discovery of a new Bagworm Moth species, in the
Annals of the Entomology Society of America. Unlike nearly all other Bagworms,
Perisceptis carnivora have predatory larvae. Strangest of all, according to Annette Aiello, staff scientist at the Smithsonian Tropical Research Institute, the adult moths wrap their eggs individually in beautiful cases fashioned from golden abdominal hairs called setae, a behavior unique among insects.
Scientists find new clues to explain Amazonian biodiversity
Ice age climate change and ancient flooding—but not barriers created by rivers—may have promoted the evolution of new insect species in the Amazon region of South America, a new study suggests.
Chinese ants show promise for fighting arthritis, other diseases
Ants may be an unwelcome intruder at picnics, but they could soon be a welcome guest in your medicine cabinet. Chemists in China report identification of substances in a certain species of ants that show promise for fighting arthritis, hepatitis, and other diseases. Their study is scheduled for the April 25 issue of ACS’
Journal of Natural Products.
Playing dead is no game for ant survival
Pretending to be dead is an effective self-defense strategy adopted by young fire ant workers under attack from neighboring colonies. This tactic makes them four times more likely to survive aggression than older workers who fight back.
Scientists reveal ants as fungus farmers
It turns out ants, like humans, are true farmers. The difference is that ants are farming fungus. Entomologists Ted Schultz and Seán Brady at the Smithsonian’s National Museum of Natural History have published a paper in the March 24 issue of the journal
Proceedings of the National Academy of Sciences, providing new insight into the agricultural abilities of ants and how these abilities have evolved throughout time.
Attack of the invasive garden ants
An ant that is native to Eurasia is threatening to become the latest in a procession of species to invade Europe, as a result of inadvertent human introduction. Research published in the online open access journal BMC Biology demonstrates that the invasive garden ant, Lasius neglectus, which is a threat to native species, may already be more widely established than expected.
