Some termite species have figured out how to enjoy the shelter of the immense, complex nests that the insects build without contributing to their construction. They avoid the full wrath of their builder hosts by being extremely easy-going.
Animals that live in the dwellings of another species without affecting them are known as inquilines. Inquiline termites (Inquilinitermes microcerus) are unique among termites in being unable to make their own nests. Instead, they inhabit the labyrinthine hallways built by another termite, Constrictotermes cyphergaster. Until now, it has been unclear how the two parties kept peaceful in such tight quarters, because termites are typically very aggressive towards outsiders.
Helder Hugo at the University of Konstanz in Germany and his colleagues collected C. cyphergaster nests in the Brazilian Cerrado and brought them into the laboratory. They then placed host and tenant termites in either open or more constricted miniature arenas and used video to track and record the ways in which the two species reacted to each other.
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Right from the start, the inquiline termites moved around less than their hosts and interacted little with them, even in the more confined arena.
鈥淢any times,鈥� says Hugo, 鈥渨hen two unrelated colonies are put together in a single confined space 鈥� such as an experimental arena 鈥� the outcome is warfare with losses from both sides.鈥�
But that didn鈥檛 happen here. Despite attacks from host termites, the tenant termites were acquiescent. Hosts would bite or spray the inquilines with acrid chemicals, but their targets never responded in kind, opting to flee. Some ignored the hosts completely.
鈥淲e did not expect that they would never retaliate,鈥� says Hugo, noting that the inquilines are capable of protecting their own colony with snapping jaws.
At most, the lodger termites would squirt faeces towards a threatening host termite, surprising their assailant long enough to retreat. 鈥淏y preventing conflict escalation, inquiline termites may considerably improve their chances of establishing a stable cohabitation with their host termites,鈥� says Hugo.
Emma Vitikainen at the University of Helsinki, Finland, says it is surprising that the tenant termite鈥檚 de-escalation strategies are so effective at blunting their hosts鈥� aggression. It means that 鈥渢he cycle of revenge is not a necessary or unavoidable outcome鈥�, she says.
鈥淧assiveness does not necessarily lead to defeat, but can be a very useful strategy, saving energy and resources,鈥� she adds. 鈥淣ature may not always be red in tooth and claw,聽and aggression is not聽inherently any more successful or beneficial a strategy than 鈥榗owardice鈥�.鈥�
Ecology and Evolution
