Dynamic expansion in recently introduced populations of fire ant parasitoids (Diptera: Phoridae) |
| |
Authors: | Edward G LeBrun Robert M Plowes Lawrence E Gilbert |
| |
Institution: | (1) Section of Integrative Biology, Brackenridge Field Laboratory, University of Texas at Austin, 2907 Lake Austin Blvd, Austin, TX 78703, USA |
| |
Abstract: | Combating invasive species requires a detailed, mechanistic understanding of the manner and speed with which organisms expand
their ranges. Biological control efforts provide an opportunity to study the process of species invasions and range expansions
under known initial conditions. This study examines the rate, pattern and mechanisms of spread for two populations of the
biological control agent Pseudacteon tricuspis, phorid-fly parasitoids of imported fire ants. We employ a trap-based survey method that detects phorid flies in low-density
populations, and provides data on abundance. This technique allows us to differentiate between continuous population spread
and effective long-distance dispersal and to examine density gradients of phorid flies across the expanding population front.
We find that occupied sites in front of the leading edge of continuous populations were common; forming small populations
we refer to as satellite populations. Satellite populations are tens of kilometers from the nearest possible source. Wind
governs the dynamics of spread in these two central Texas populations. Population edges expanding with the wind exhibited
a higher frequency of effective long-distance dispersal than did populations expanding into the wind. This enhanced effective
long-distance dispersal rate translated into a five times faster rate of spread for population edges traveling with the wind.
This planned invasion shares many characteristics in common with unplanned species invasions including: protracted establishment
phase during which densities were below detection thresholds, and slow initial spread immediately after establishment followed
by rapid, accelerating spread rates as population sizes grew. |
| |
Keywords: | Biological control Invasive species Long-distance dispersal Population spread Pseudacteon tricuspis Range expansion Solenopsis invicta Wind dispersal |
本文献已被 SpringerLink 等数据库收录! |
|