4:28 p.m. - 2004-01-28
Gasterflagging With Dr. Bruce
This is your pal Dr. Bruce, and I have good news for those of you who may have wondered what possible use yellow jacket wasps serve in nature. I'm not sure how widely distributed this wasp group, the Vespidae, is outside of North America so I'll stick to N.A.
The short answer is that yellow jackets can be important seed dispersers for a surprising number of native plants such as Trillium species. Both ants and yellow jackets are attracted to many seeds because the seeds carry small fatty structures called elaiosomes that provide important nutrition to the insects.
Ants have long been known as seed dispersers. There's even a Greek-based word for this activity, myrmecochory, from the Greek words "myrmeco" (ant) and "khorein" (to spread about). Ant species that do this activity are found on all continents (except Antarctica).
What brings me to all of this (since my main thang is as a fish ecologist...) is an article in the recent issue of the journal Southeastern Naturalist studying the interactions of yellow jackets and ants in South Carolina. It turns out that yellow jackets are aggressive seed thieves, trying to steal seeds from ants as the ants move seeds home. But some ants are better than others at protecting themselves.
If you ever see an ant rear up threateningly, this is an example of gasterflagging. This is when the ant displays its abodomen ("gaster") and is flagging an antagonist's attention by making such a display. Apparently if an ant carrying seeds is willing to put them down and gasterflag an attacking yellow jacket, the yellow jacket will usually back down. Some ant species are good at this, some aren't. Not surprisingly, fire ants are excellent gasterflaggers.
Ants known to most Americans on this list are important seed dispersers (and gasterflaggers) including the various species of carpenter ants (genus Camponotus) and argentine ants, the small ants that can suddenly appear in droves in your house in summer. (Ruth is known to dislike argentine ants, just ask her!)
So if you find a yellow jacket nest somewhere on your property, think twice about going psycho with them. They actually serve an important ecological function as seed dispersers, so that native plants can get their seeds into as much of the best habitat as possible. Same with ants--but it's OK to keep them out of your kitchen(!).
As an aquarium follow-up, I spent the weekend cleaning 120 pounds of "builders sand" from Home Depot by repeatedly rinsing it out in ~20 pound batches to remove superfine dust, and then putting it in to my new tank. The tank has finally cleared out again from what I couldn't rinse out, and I continue to age the water, a process called cycling. With 3-4 inches of sand on the bottom I hope to establish what's called live sand, full of beneficial bacteria and other small organisms that will help keep the tank in chemical balance. Next step: lights and plants.
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