The Termite-Eating Nepenthes

Plants and eusocial insects have some interesting ecological relationships with one another. A vast majority of these relationships are between a plant a members of the order Hymenoptera (ants, bees, and wasps), but what about those other eusocial insects, the termites?

Despite the social similarities they share with many ants, bees, and wasps, termites are actually distant relatives of the cockroaches. As many already know, termites also have a relationship with plants. Thanks to symbiotic bacteria residing in their gut, termites are able to make a living eating wood and building massive colonies, sometimes in undesirable locations like in the framework of your house. However, there is at least one species of plant out there that has evolved a different kind of relationship with termites.

Meet Nepenthes albomarginata. Native to Borneo, Malaysia, and Sumatra, this tropical carnivore seems to have a taste for termites. However, unlike flies or ants that are attracted to sweet nectar, termites have a different palate. Feeding on plant materials, termites don't necessarily seem like the kind of insect a plant would want to attract. N. albomarginata has seemingly found a way to attract tasty termites without becoming a meal itself.

As the specific epithet suggests, there is a white ring located around the margin of the pitchers' mouths. The ring is made up of a dense coat of hairs called trichomes. It was discovered that sometimes this white ring would disappear overnight. The pitchers without the white ring were also chock-full of partially digested termites. Just how the termites find these pitchers isn't quite certain. Researchers have not yet been able to isolate a scent compound.

Either way, the termites swarm the ring. While many termites make off with a free meal, plenty more of them slip and fall into the trap. It has been found that N. albomarginata obtains upwards of 50% of its nitrogen needs from termites in this way. What's more, all of this happens in a span of a single evening. Once the ring is picked clean, the pitchers are no longer attractive to the termites. They go their way and the plant has its meal. Because of the social structure of these peculiar insects, the loss of these individuals is never high enough to represent a serious selective pressure.

Further Reading: [1]