Tandem Termites

ear with me: Imagine you’re a female termite in love.

Or something like it: Mated to another, together you seek a new nest site by performing an innate mating ritual. You grasp onto the abdomen of your mate, frequently touching his legs with your antennae as you explore new territory.

But suddenly, your mate stops. Struggles. You don’t know why, and you refuse to let go. So — still grasping his abdomen — you attempt to circle him, curving your body closer to his.

And then the reason he stopped is clear. His six legs are coated in sticky resin from the tree you were climbing. Now, yours are, too. Driven by pheromones, you won’t let go, holding on as you attempt to circle the other way until you’re both covered in resin, you’re both stuck, and soon, you’re both dead.

In 38 million years, you and your mate will still be encased in that resin — now fossilized amber — and for sale in an e-shop for fossil collectors.

A unique amber fossil containing two such termites was purchased by Ales Bucek, head of the Laboratory of Insect Symbiosis at the Czech Academy of Sciences, and shared with Nobuaki Mizumoto, then at the Okinawa Institute of Science and Technology and today an assistant professor in the College of Agriculture at Auburn University.

“Termite fossils are very common, but this piece was unique because it contains a pair,” Bucek said. “I have seen hundreds of fossils with termites enclosed, but never a pair.”

The fossil is the only known example of a pair of now-extinct Electrotermes affinis termites, and the findings from this particular fossil were published in Proceedings of the National Academy of Sciences, a leading, peer-reviewed scientific journal.

“Amber provides one of the most detailed and vivid records of extinct life,” Mizumoto said. “However, the process of fossilization may distort the true picture of past organisms and bias evidence.”

The reason for this is how slowly amber fossilizes. Typically, fossils are formed by the quick covering of an organism with sediment. But because the termites could move in the resin before it solidified into amber, the position of the termites is not necessarily reflective of their behaviors.

In this case, the termites — one male and one female — in the Baltic amber inclusion show a head-to-abdomen contact that resembles the courtship behavior of termites today called the “tandem run.” During this mating behavior, the insects display coordinated movements to stay together while exploring a new nest site.

However, one of the extinct termites is turned parallel to its partner — a variable from how this behavior is seen today.

Mizumoto and his colleagues had a theory about why the positioning was different, so they simulated the fossilization process in the lab.

“Our approach focused on how fossils are created and how behavior changes during the insect’s death,” Mizumoto said. “We simulated the first stage of amber formation by exposing living termite tandems to sticky surfaces. We found that the posture of the fossilized pair matches trapped tandems and differs from untrapped tandems.”

The experiment showed that even if the leading termite got trapped on a sticky surface, the follower would not abandon its partner but try to walk around them — resulting in a position very similar to the pair immortalized in amber.

“Thus, the fossilized pair likely is a tandem running pair,” Mizumoto said. “This is the first direct evidence of the mating behavior of extinct termites.”