Mechanisms of interspecific competition among an invasive and two native fire ants

Authors
Citation
Lw. Morrison, Mechanisms of interspecific competition among an invasive and two native fire ants, OIKOS, 90(2), 2000, pp. 238-252
Citations number
95
Categorie Soggetti
Environment/Ecology
Journal title
OIKOS
ISSN journal
00301299 → ACNP
Volume
90
Issue
2
Year of publication
2000
Pages
238 - 252
Database
ISI
SICI code
0030-1299(200008)90:2<238:MOICAA>2.0.ZU;2-I
Abstract
The mechanisms of interspecific competition among an invasive and two nativ e Solenopsis fire ant forms were investigated in a series of laboratory exp eriments. In separate trials each with a different food resource, the nativ e S. geminata x xyloni retrieved the greatest amount of a protein- and lipi d-rich artificial food resource and a high protein natural food resource, a nd the native S. geminata retrieved the greatest amount cf a high carbohydr ate food resource. In trials investigating aspects of interference competit ion at the colony level, the invasive SI invicta proved to be initially mor e aggressive than S, geminata, but less aggressive than S. geminata x xylon i Solenopsis invicta eventually controlled more of the foraging arenas agai nst both native forms when colonies were equivalent by worker biomass, but not when colonies were equivalent by worker number. When paired with S. inv icta, S. geminata suffered a significantly greater proportional reduction i n both workers and entire colonies when colonies were initially standardize d by worker biomass, but not when colonies were standardized by worker numb er. When paired with S. invicta, a significantly greater proportional reduc tion of workers occurred in S. geminata x xyloni, regardless of how colonie s were standardized. Ln pains ise trials at the individual level. majors al ways exhibited significantly less mortality than miners, regardless of the Solenopsis form. The majors of both native Forms suffered significantly les s mortality than those of S. invicta. Superiority in colony-level interfere nce ability appears to be an important mechanism allowing S. invicta to dis place native Solenopsis forms. The ability of S. invicta to reach high popu lation densities, because of intrinsic biological characteristics or an esc ape from natural enemies, plays an important contributory role. Similar mec hanisms may underlie the success of other invasive ant species.