The Hobbesian World of Wasps and Figs

An amazing instance of symbiosis from a recent paper entitled, "Host sanctions and pollinator cheating in the fig tree–fig wasp mutualism" (available here).

Figs and fig wasps have lived in symbioses for centuries — wasps lay their eggs in figs, and pollinate the trees as recompense. But it's not all altruism. The trees will fight back if the wasps renege on the deal.

The symbiotic relationship has been in existence for around 80 million years, with the wasps stashing their eggs in the fig fruits where they can develop safely, and pollinating the plants in return for the service. This relationship is so functional that there are over 700 different figs and wasp species pairs that engage in it...

If the wasps don't do their duty, the trees respond by enacting a sanction — aborting their fruit, killing off the teeming mass of baby wasps. A new study of this killer tree phenomenon, published in Proceedings of the Royal Society B comes from Cornell University and The Smithsonian Tropical Research Institute, shows that negative reinforcement may be an important part of symbiotic relationships...

...In the actively pollinating groups, the tree species that tend to enforce sanctions less often have a higher occurrence of freeloader wasps, who take advantage of the figs without doing any of the work. Inversely, by using the sanction option more frequently, some fig species have a lower incidence of non-pollinating insects.