Response of an open-forest ant community to invasion by the introduced ant,Pheidole megacephala

Abstract

The introduced tramp ant, Pheidole megacephala, is a well-known pest of urban areas and coastal dune ecosystems in eastern Australia. Until recently, establishment and spread of P. megacephala colonies has been regarded as likely only in disturbed areas. Here we describe the extent of an established colony of P. megacephala in a long undisturbed open forest near Maryborough in southeast Queensland and compare ant community structure with those of nearby uninfested sites. Tuna baiting revealed three distinct zones: (i) a zone totally dominated by P. megacephala (at least 10 ha) where few other ant ant species were detected; (ii) a zone where P. megacephala was absent and many other ant species were found; and (iii) a zone where opportunists (species of Ochetellus and Paratrechina) competed with P. megacephala at baits. Pitfall trapping over a 9-month period resulted in 12 species being recorded at the infested site, compared with a mean of 25 species recorded at adjoining uninfested forest. Over 94% of ants recorded in pitfalls at the infested site were P. megacephala. Most notably, P. megacephala had completely displaced dominant Dolichoderines (species of Iridomyrmex), subordinate Camponotini (species of Camponotus, Opisthopsis and Polyrhachis) and other species of Pheidole which are common at forest sites.

Global warming may freeze the invasion of big-headed ants

“…Wetterer 2007;Vanderwoude et al 2000;Hoffmann and Parr 2008). South America is the continental region with the currently largest proportion of suitable habitat (54 % South American landmass is favourable) and Europe is the lowest (4.1 %).…”

“…The species is believed to be native to southern Africa and has already invaded various types of habitats worldwide, such as agricultural areas (Wetterer 2007; IUCN SSC Invasive Specialist Group 2012), coastland (Fisher 2012), forests (Fisher 2012;Hoffmann et al 1999), riparian zones (IUCN SSC Invasive Specialist Group 2012), shrub lands (Wetterer 2007; IUCN SSC Invasive Specialist Group 2012), wetlands (IUCN SSC Invasive Specialist Group 2012; Fisher 2012) and urban areas (Wetterer 2007;IUCN SSC Invasive Specialist Group 2012;Fisher 2012). Although the species is frequently associated with disturbed habitats, it has also been found to invade undisturbed open forests, displacing dominant ant species (Holway et al 2002) and causing the local loss of several functional groups of ants (Vanderwoude et al 2000). Pheidole megacephala is very aggressive towards other ant species and has a heightened ability to recruit efficiently many workers and to raid nests of competing ant species (Holway et al 2002;Dejean et al 2008).…”

Ant communities (Hymenoptera: Formicidae) in an urban ecosystem near the Atlantic Rainforest

“…megacephala may be responsible for the death of native invertebrates, ants in particular Vanderwoude et al, 2000), and they indicate that they are dominant in houses and other environments intensively impacted by humans Delabie et al, 1995). Their negative association with P. longicornis and S. saevissima ( Figure 5) has already been reported by Delabie et al (1995), however their antagonism with L. humile as described by Haskins and Haskins (1965), Crowell (1968) and Delabie et al (1995), could not be verified, as this native species appeared in Thus, the presence of native vegetation in the yards and gardens of the houses, or of the forest near the neighborhoods, may possibly be allowing the existence in an urban area of some taxa which are characteristic of the forest area, which over time, can generate a positive impact on the maintenance of the biodiversity of this ecosystem.…”

Structure-Invading Pest Ants in Healthcare Facilities in Singapore

“…The high abundance of this species in some locations may occur because few other ant species are present in locations where P. megacephala occurs. Invasion by P. megacephala reportedly reduced the native ant species and other invertebrate species (Tryon 1912, Vanderwoude et al 2000, but its foraging activity declined when other tramp ant species (e.g., P. longicornis and M. pharaonis) were present (Loke & Lee 2004).…”