bks@alfa.berkeley.edu ( Brad Sherman ) (01/14/89)
Thanks to all for responses to my questions about the invasion of
the San Francisco Bay area by the Argentine ant ("Iridomyrmex humilis").
From memory:
I. humilis is an advanced ant form. There are no nuptial flights or winged
forms. Colonies are diffuse organizations with more than one queen. New
colonies are formed by "budding." They are fierce predators of other ants.
I hope this predation carries over to termites (my house is over 80 years old),
although I found no evidence of this.
I. humilis is characterized by "nervousness," colonies habitually change
nesting sites in reaction to changes in the microenvironment. Thus both
lack or surplus of heat or water can cause them to migrate. It is reported
that upon location of a superior nesting site the colony will begin moving
within minutes. Queens walk and broods are carried.
I have not yet found any info to refute the estimate of 10^5-10^6 neurons.
There is apparently some interesting adaptation of the myelin sheaths in ants
to allow more dendrites in the restricted volume.
Spanish settlers in the Carribean were forced to abandon entire islands
due to ant infestation (not necessarily I. humilis). Ants have been referred
to as the King of Brazil.
"Insect Societies," by Edward O. Wilson is an excellent book, although I
am in no way qualified to comment on its scholarship. He estimates that
there are 10^15 ants alive on the planet at any time.
-Brad Sherman (bks@ALFA.Berkeley.Edu)