Ant species accumulation on Lord Howe Island highlights the increasing need for effective biosecurity on islands

Abstract

Islands are particularly noteworthy for global conservation because of the high number of species they host, the high levels of species endemism, and the large number and proportion of species at risk of extinction. Much of the conservation threat on islands is from invasive species. Whilst biosecurity is an increasing focus of attention for authorities globally, species are continuing to establish in new locations outside of their native ranges. Among invasive species, ants are a prominent taxon, especially on islands. Over the past decade, following the detection of one of the world's worst invasive ant species, African big-headed ant Pheidole megacephala, the environmental management authority on world-heritage-listed Lord Howe Island has focused attention on invasive ants. This detection influenced the creation of biosecurity measures to prevent further incursions of exotic species, particularly ants. Despite these efforts, over the following decade numerous ant species were collected on the island for the first time, indicating a serious biosecurity problem. Here, we investigate the chronosequence of ant introductions to Lord Howe Island to quantify the extent and nature of the island's ant biosecurity problem. A total of 45 species have been collected on the island and of these, 12 are considered to be endemic, and a further seven are possibly native. Nineteen of the 26 introduced species (42% of the total fauna and 73% of the introduced fauna) were only found for the first time in the last 15 years. All but two of the species that are not native to Lord Howe Island are native to the Australian mainland, indicating that the biosecurity threat comes from the transport of goods from the Australian mainland. We suggest that the pattern of accelerating ant species accumulation on Lord Howe Island is probably not an isolated phenomenon, and that it is probably occurring on most islands globally that are habitable by ants and visited by people.

Ant interceptions reveal roles of transport and commodity in identifying biosecurity risk pathways into Australia

“…Finally, in addition to inspection on arrival, more effort needs to be placed on inspection in high-risk ports of departure. Implementing port-of-departure biosecurity measures can be very effective at reducing contamination of goods as evidenced in New Zealand where ant presence in containers dropped from 17% to less than 1% (Nendick et al 2006;Hoffmann et al 2017).…”

“…Over 150 ant species have become established outside their native range, and island ecosystems appear particularly susceptible (McGlynn 1999;Suarez et al 2010). For example, many islands that historically maintained unique, depauperate or no native ant diversity, now harbor communities dominated by introduced species (Morrison 1996;O'Dowd et al 2003;Krushelnycky et al 2005;Smith and Fisher 2009;Ward 2009;Cerdá et al 2012;Sarnat and Economo 2012;Hoffmann et al 2017). Despite over a century of research on the consequences of ant invasions, we know relatively little about which taxa are transported by human commerce or the biogeographic patterns of ant introductions.…”

Strumigenys perplexa (Smith, 1876) (Formicidae, Myrmicinae) a new exotic ant to Europe with establishment in Guernsey, Channel Islands

“…Individuals have distinctively smaller mandibles and overall length, amongst other characters (Brown 1955). Introduced populations of S. xenos have been recorded in populations of S. perplexa in both New Zealand and Lord Howe Island (Brown 1955;Taylor 1968;Hoffmann et al 2017). The species could potentially have followed S. perplexa in a similar fashion or will follow in the future if introductory routes remain open.…”

Epiphyas intrepida sp. nov. (Lepidoptera: Tortricidae): an endemic, not a stowaway, on Lord Howe Island

“…Hoffmann et al . (2017) also highlighted the importance of distinguishing native from exotic insects on Lord Howe Island as a means for uncovering biosecurity threats. Therefore, to promote further DNA‐based research on the island's native insects, support conservation efforts involving rare and significant species and communities of the LHIG, and inform decision making regarding biosecurity‐related issues on the island, it is essential that Bradley's endemic tortricid be recognised as such, and named.…”