Biology Reference
In-Depth Information
Argentine ants, described above, the region near Rosario, Argentina,
appears to be the logical location to search for possible biological control
agents. It has been suggested that the success of Argentine ants in areas to
which they have been introduced is due to escape from particular para-
sitoids, a fly of the family Phoridae. Phorid flies are known to attack other
ants of the genus
Linepithema
in Brazil, but not the Argentine ant itself. In
any case, these parasitoids are not known from the Rosario area. Thus, it
appears that other possible biocontrol agents should be sought in the areas
now known to be the source of Argentine ant introductions.
Genetic studies of variability and source areas have additional implica-
tions for biological control. For example, given that butternut canker is an
introduced fungus with low genetic variability (Furnier et al. 1999), a
search for resistant butternut genotypes may well be worthwhile.The low
genetic variability of the canker fungus may limit its ability to overcome
such resistance.
Introduction Sources and Evolution
This chapter emphasizes the fact that modern systems of transport bring
together populations of alien species from many world regions. Often, the
populations of a single species are the product of multiple introductions,
in some cases from very different parts of their native range. Furthermore,
some alien forms, on detailed genetic analysis, turn out to be related but
distinct taxa. These forms are being introduced to geographical regions
that often contain related species from which they have been isolated in
space. Thus, intercontinental dispersal of species is creating the potential
for interbreeding of related but previously isolated taxa. In the next chap-
ter, we will examine the processes of hybridization that result and explore
their evolutionary significance.
