Just getting around to catching up on my email after getting back from
Mexico for the holidays. Bill Mixon said:
One species of leaf-cutters, Atta wollenweideri, uses a trail-marking pheromone
so powerful that 1 milligram of it would suffice to lay a trail that could lead
a fellow worker ant 60 times around the world. Even spread that thinly, there
would still be 2 billion molecules per meter of trail.
That reminds me of a chemistry seminar I attended once about insect
pheromones. The speaker had identified what he thought was the active
ingredient in the sex pheromone of some kind of moth. He synthesized it and
put it in insect traps to test it out. To his great surprise, he caught no
moths. He later discovered that he was using way too much; so much so that all
of the moths were overcome by its effects and had dropped to the ground many
meters away from his traps, writhing and no longer able to fly. After he
finally figured out the correct dosage, he determined that the moths could not
only detect, but could actually follow, a trail at a concentration of only one
molecule per cubic meter of air. Now that's powerful stuff!
Mark Minton
