Termites that evolve into king and queens can grow their brains before they leave the nest

Termites have been around for more than 120 million years, but scientists have just learned that some members of the insects can grow the size of their brains when they are about to leave the nests.

Researchers at Drexel University have learned that king and queen dampwood termites — the only members of the swarm to leave the nest — can grow the optic lobe part of their brain as they are about to leave the nest to mate and build other dwellings.

They found that the regions in the brain matched the insect’s cognitive demands—but the changes in the brain happened before they knew they needed it.

This suggests it happens when the insect is developing into a certain ‘caste,’ in this case, a king or queen.

King and queen dampwood termites can grow the optic lobe part of their brain

‘The term ‘caste’ when applied to insect societies—is the idea that you have specialized individuals that play different roles,’ said the study’s lead author, Drexel University professor Sean O’Donnell in a statement.  

‘Neuroecology explores how brains evolve and develop with the idea that the brain structure of an individual is going to be shaped by the demands it faces.

‘Learning that the kings and queens have different visual investment is important, but not super surprising—what is special was our ability to identify and measure the developmental stage that is the precursor to an individual molting into a king or queen.’

The experts used their knowledge of the dampwood termites and how they develop to predict what needs different brain tissues would have, depending upon the role.

During the first three stages of a termite’s life, they do not vary much. However, when a nymph reaches the fourth stage, it can become a winged king or queen, a worker, soldier or wingless reproductive.

It’s at this stage, when the brain starts to change in anticipation of potentially leaving the nest and procreating and starting a new colony.

‘Some nymphs have tiny developed wing pads—this stage does not leave the nest, they are not technically a king or queen yet, but changes in the brain architecture in that stage are happening and setting up the brain for the capacity to be used in a light bright environment,’ O’Donnell added. 

‘The brain change happened earlier in development than needed. 

‘This is surprising and exciting, as this kind of anticipatory brain development is not seen very often, as well as the fact that, with some accuracy, we can predict the developmental future of an individual and it looks as though the brain is tracking that trajectory, although it’s not being used yet.’ 

The increase  in brain size matched the insect’s cognitive demands, but the changes occurred before it was needed

This shows that some dampwood termites are ‘experience-expectant,’ meaning their brains change before the change is needed.

‘Experience-expectant brain tissue growth is rarely documented in insects, likely because it entails high potential costs of tissue production and maintenance and relatively low immediate sensory/cognitive benefits,’ the researchers wrote in the study.

Though rare, there are cases of honeybees that have demonstrated ‘experience-expectant’ changes, suggesting they may also grow the sizes of their brains depending upon tasks.

More research is needed to look into how the investment in added brain tissue could be offset prior to getting the payoff of leaving the nest.

For kings and queen dampwood termites, O’Donnell said it could result in mating flights shortly after they reach adulthood.

The study was published earlier this week in the Science of Nature.