The role of opportunity in the unintentional introduction of nonnative ants

Abstract

A longstanding goal in the study of biological invasions is to predict why some species are successful invaders, whereas others are not. To understand this process, detailed information is required concerning the pool of species that have the opportunity to become established. Here we develop an extensive database of ant species unintentionally transported to the continental United States and use these data to test how opportunity and specieslevel ecological attributes affect the probability of establishment. This database includes an amount of information on failed introductions that may be unparalleled for any group of unintentionally introduced insects. We found a high diversity of species (232 species from 394 records), 12% of which have become established in the continental United States. The probability of establishment increased with the number of times a species was transported (propagule pressure) but was also influenced by nesting habit. Ground nesting species were more likely to become established compared with arboreal species. These results highlight the value of developing similar databases for additional groups of organisms transported by humans to obtain quantitative data on the first stages of the invasion process: opportunity and transport.biological invasions ͉ introduced species ͉ invasive ants ͉ propagule pressure

Characteristics of exotic ants in North America

“…Even although sub-samples of ant species introduced to North America exist (Suarez et al 2005), it is impossible to know all ant species that were introduced to North America and all that were not. We can, however, speculate to which extend observed differences between ex- otic and native ant species are influenced by an introduction bias (Blackburn and Duncan 2001;Cassey et al 2004;Jeschke and Strayer 2006;Blackburn and Jeschke 2009;van Kleunen et al 2010).…”

Traits related to biological invasion: A note on the applicability of risk assessment tools across taxa

“…Invasive ants tend to be ground nesters rather than arboreal (Suarez et al 2005), and invasive wasps tend to nest in urban rather than rural or natural habitats (Downing et al 2012). Invasive ants and wasps may exploit nest resources not used by their native counterparts (Suarez et al 2005), leading to their successful establishment.…”

“…Invasive ants tend to be ground nesters rather than arboreal (Suarez et al 2005), and invasive wasps tend to nest in urban rather than rural or natural habitats (Downing et al 2012). Invasive ants and wasps may exploit nest resources not used by their native counterparts (Suarez et al 2005), leading to their successful establishment. Invasive wasps also tend to encounter less nest predation as a result of their nest location choice (Cervo et al 2000), and in the case of predation, are more likely to re-nest (Gamboa et al 2004).…”

“…Nesting: The habitat used by nesting insects (Suarez et al 2005, Downing et al 2012, tendency of the nest to be predated (as a result of mimicry or habitat selection; Cervo et al 2000), re-nesting after predation (Gamboa et al 2004), and general nest reuse (Cervo et al 2000) have all been claimed to be related to insect invasion in different ways. Invasive ants tend to be ground nesters rather than arboreal (Suarez et al 2005), and invasive wasps tend to nest in urban rather than rural or natural habitats (Downing et al 2012).…”

“…Nesting habitat Ground nesting ants more likely to establish than arboreal ants (Suarez et al 2005);…”