The latest issue of Agricultural Research, a monthly must-read ’round Microkhan headquarters, contains an interesting nugget about fire ant immigration patterns. A Floridian entomologist who specializes in evolutionary genetics has concluded that our national fire-ant nightmare started with as few as nine queens, all of whom touched down in Mobile, Alabama, during the Great Depression. It is generally assumed that these early invaders, who originated in South America, stowed away in the vast lumps of soil that old cargo ships used as ballast.
Our natural follow-up question to this report, of course, is “Why Mobile?” Turns out we’re not the only ones to wonder:
Perhaps we should ask not, Why Mobile?, but rather Why not New Orleans? or Pensacola? During the first half of the 20th century, New Orleans received more cargo from South America than did either Pensacola or Mobile. During the same period, New Orleans was swept by another exotic species, the Argentine ant, which became so abundant that it was colloquially known as the “New Orleans ant.” This virulent invader wiped out most of the native ants in the New Orleans area and may have prevented S. invicta and S. richteri from becoming established there. If so, then why not Pensacola, which was free of Argentine ants? Why did both fire-ant species first appear in Mobile and only in Mobile? Wilson speculates that S. richteri “preconditioned” the native ant community to ease the entry of S. invicta. In view of the superior competitiveness of S. invicta, it would hardly seem to have needed the help. We will never really understand why Mobile. Whatever charm the city holds for ants must simply be accepted, much like the southern hospitality on which Mobile prides itself.
We wonder whether the fire ants simply wanted to participate in the city’s unique form of Mardi Gras.
(Image via The Civil War)