The wasps do WHAT?

Figs. Their leaves have acted as preservers of modesty for millennia, they are lovely with Parma Ham and nothing beats a fig jam and soft cheese breakfast wrap (honestly, food of the gods). They are also sex dungeons.

Sex dungeons for wasps, that is. Well, perhaps ‘procreation dungeons’ is a better description but that doesn’t have the same ring to it. Fig wasps have a complicated and fascinating relationship with their fruity boudoirs and I’m about to go into the saucy details.  A small warning, you may never be able to look a fig in the eye ever again.

Firstly, let’s clear up what a fig actually is. Imagine a Daisy. Daisies are made up of lots of tiny, individual flowers in one big ‘pseudanthium’ (or ‘false flower’ for those of us who weren’t classically educated). Turn said Daisy in on itself, stitch up the edges and you have what is basically a fig. This structure is called a syconium and contains many tiny flowers. There are always 3 types of flowers; male, fertile female and sterile (gall) flowers. For the purposes of this explanation we’re going to assume they’re all in the same fig, although often they can be in separate figs (as we’ll see later). At the top of each fig is a little opening through which a female fig wasp, let’s call her Momma Waspy, can crawl. She fertilises the female flowers with the pollen from her mother fig and lays her eggs in the gall flowers.

Once the eggs hatch out, the males and females mate. In some species, males hatch out first and, in what apparently passes for good manners in the insect world, use this opportunity to fertilise their unborn female roommates before they hatch. These noble gents perform one last useful act of burrowing out of the fig leaving holes through which the females may later emerge and then, having fulfilled their evolutionary function and hence finding themselves useless, promptly drop dead. When the females hatch, possibly already fertilised, they get a dusting of pollen from the male flowers in the fig (yet more male gametes foisted upon them) and crawl out into the world to continue what is rapidly coming to resemble a particularly nasty story line of East Enders.

This is a picture of a fig I took in Indonesia. It had been chewed on by a Bear Cus Cus. I like to think that you can see the remains of a Momma Waspy near the top, but that may just be dirt.

This is a picture of a fig I took in Indonesia. It had been chewed on by a Bear Cus Cus. I like to think that you can see the remains of a Momma Waspy near the top, but that may just be dirt.

‘But’, I hear you cry, ‘What am I eating? I don’t know any more! I don’t think I even want to know!’ which is entirely understandable, seeing as figs appear to be nothing short of sordid pits of vice, and no one likes eating those. Luckily, however, most of the figs we eat are either parthenogenic (not needing fertilisation) or consist of only fertile female flowers. In these figs, Momma Waspy pushes her way in, fertilises the female flowers but finds no gall flowers to lay her eggs in. Disaster! And there’s no escape; the act of getting into the fig through the narrow hole has removed her wings and antennae so she’s effectively trapped. The reason we don’t find these poor, blighted creatures inside our figs is because the fruit produces enzymes which digest her. Yes, that’s right. Digest. Isn’t nature beautiful? So you might eat a bit of wasp (or wasp juice) along with your figs, but it was probably worse for the wasp, really.

Evolutionary biologists love figs and fig wasps as they’re a nice example of co-evolution. The wasps can’t live without the figs and vice versa. Apparently the syndrome first evolved around 80 million years ago and has diversified ever since with there now existing hundreds of different species of fig wasp and fig tree. I’ve only covered a tiny proportion of the huge diversity within this mutualistic freak-show, and the evolutionary theory behind it all is really quite cool (and complicated) so if you want to read more, here are some fun and useful links:

http://science.howstuffworks.com/zoology/insects-arachnids/fig-wasp.htm

http://www.wildsingapore.com/wildfacts/plants/others/ficus/ficus.htm

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About adelecmj

I'm a PhD student at the Open University, where I study pollen-vegetation relationships in Ghana. I like plants, rocks, and science in general.
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One Response to The wasps do WHAT?

  1. Pingback: Big new wasp species discovered in Indonesia | Dear Kitty. Some blog

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