We might not think grandma and grandpa would make the best front-line soldiers, but the insect world has a different military strategy. Soldier termites put their oldest militiamen on the frontlines in defense against carnivorous ants, a new study in Biology Letters suggests.
While it might seem counterintuitive, the strategy actually allows for the entire colony to get the most out of each little termite’s life cycle by sacrificing the older soldiers closer to death anyhow.
Termites are social insects whose colonies are comprised of different castes that work together to ensure the survival of the queen, who can lay an astonishing 30,000 eggs in one day. These eggs grow into workers, reproducers, and soldiers. The soldiers use their massive heads as the first line of defense against hungry ants by plugging any holes with their noggin – the ultimate self-sacrifice. If that fails, they use their enormous mandibles (jaws) to chomp down on the ants, who snack on the delicious and nutritious termites.
It's like a scene from Alien vs. Predator, except, you know, it's real life.
Researchers plopped two soldiers and five workers inside a fake nest and placed a predatory ant near the only exit. In dozens of trials, it was almost always the older soldier who went to plug the hole, with the older, sterile female soldiers more likely to take on an ant than males.
The old fogies weren’t necessarily better at defending the nest, however. This suggests it wasn’t their experience but rather their age that got them to the front lines. While the old folks are securing the perimeter, the younger soldiers take up the role of “royal guard” and stick close to the nest in order to protect the queen.
It backs up a life-history theory that certain insects practice age polyethism – or age-based task allocation – when an animal shows different forms of behavior in different ages. Safe tasks are performed at earlier stages in life, and as an animal gets closer to death, they perform riskier work.
By keeping them safer while they’re younger, this ageist system keeps the life expectancy longer for soldiers and ultimately allows them to contribute more to the success of the colony over time. Worker termites also exhibited this same behavior; as they age, they diversify their skill set and begin working further away from the nest.
However, don’t go signing your grandparents up for the reserves just yet, the older soldiers weren’t necessarily better than the younger termites at defending the nest.