Chivalry is not dead...among fig wasps

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Admittedly, there's not much competition, but I'm declaring fig wasps to be the most gallant of all wasps. Males are the only known insects to put pregnant females ahead of themselves...even if they haven't had a chance to mate yet.

Fig wasps are a tiny variety of wasps that pollinate, unsurprisingly, fig trees. They come in about 850 different varieties, each for the slightly different types of fig trees found in the rainforest. The wasps live inside fig flowers, and, like most insect species, they are dominated by females, with only a handful or even just a single male. The wasps come in two basic types, pollinating and parasitic - you can probably guess how each type interacts with the tree.

The two types of females mate with their respective males, and eventually it's time for them to leave the fig behind. The males, on the other hand, are left behind to die, presumably because post-mating they serve no further purpose. Researchers at the University of Leeds found that neither type of female wasp is strong enough to chew her way out of the fig on her own, and at least one male is required for any of the females to escape. In both instances, the parasitic and pollinating males would chew a way out for the females to escape, then simply return to the fig to die.


But here's where we see the distinction between the brutish, savage parasitic wasps and the gentlemanly, chivalrous pollinating wasps. (Adjectives used may not be 100% objective.) The survival rates of females increased with the presence of more pollinating males, while they plummeted the more parasitic wasps were added in.

That's because the pollinating males actually worked together to free the females, even if some of them hadn't mated and thus had no personal incentive to help the females escape. The parasitic males, on the other hand, were unable to overcome their inbuilt aggression towards one another, and started viciously fighting.


Researcher Dr. Steve Compton explains:

"It would seem that male parasitic fig wasps are unable to switch off the hard-wired aggression needed to successfully mate to cooperate with each other, even when their genetic investment is at stake. Pollinators' teamwork may be prompted because of the likelihood of genetic connection to the mated females, but the parasitic fig wasps were in the same situation."


Via Biology Letters. Image by Simon van Noort via the University of Leeds.