Thomas J. Watson Fellowship Year

Diversity within a single fig

Fig wasps of family Agaonidae are famously studied with their complex life cycle documented in elegant illustrations like Encylopedia Britainica’s seen below. A striking sexual dimorphism exists between these two wasps as the males are essentially a phallus and pair of jaws, while the females are fully winged and typically exhibit elegantly elongated heads. This difference between the sexes has evolved over time as the males emerge within the fig, fertilize the female wasps before they hatch, and then chew out an escape hole from the ripening fig for the females to crawl out of. The males’ purpose is done, genes passed on, and the females escape from the fig through these little passages made by their mates.

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Wingless agaonid fig wasp male. His reduced physiology reflects his sole purposes in life: fertilization and passage production.

You may wonder how this enclosed lifestyle is made possible and the answer lies within figs being untrue fruits. The internal portions of figs are actually composed of flowers. This enclosed structure protects the fig flowers from free-loading insects. These flowers are still able to be fertilized given the obligatory mutualistic relationship between fig wasps and figs. You see, female fig wasps crawl through special openings at the bases of figs. Once inside, the female fig wasp spreads pollen that she gathered from her original host fig and pollinates several flowers as she lays her eggs within the fig. These eggs develop into male and female fig wasps over time and the cycle continues, males always emerging first, fertilizing the females, and giving them a passageway out of the fig.

fig-wasp-lifecycle

But there’s always more to these relationships, especially within the wasp world. When exploring a local variegated fig tree (Ficus variegata) in Cairns, Queensland, I came across some interesting wasps filling the ripening figs.

Parasitoid wasps of family Pteromalidae take advantage of these developing fig wasps by laying their eggs inside the other developing wasps. These parasitoids then consume the pollinating fig wasp and emerge as adults. In order to escape the fig, they rely on those passageways created by male fig wasps. The result is a treasure trove of wasps when you open a fig like the one above. All those crawling wasps are parasitoids of two main species: Sycoscapter spp. and Watshamiella spp. 

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Sycoscapter spp. (Pteromalidae) wasp that parasitizes the pollinating fig wasps (Agaonidae) by laying her eggs in the developing agaonids.
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Watshamiella spp. (Pteromalidae) wasp that parasitizes the non-pollinating fig wasp Sycoscapter spp. (pictured above).

These non-pollinating fig wasps of Pteromalidae have a dynamic relationship between each other. As the Sycoscapter spp. finds a fig to lay her eggs in, she is followed by Watshamiella spp. Both of these species use their antennae on the outside of a fig to locate where they need to drill in their long ovipositors (otherwise known as stingers). These ovipositors drill through the outer flesh of the fig to lay an egg within the developing fig wasp. The Watshamiella spp. follows the Sycoscapter spp. female around to lay her egg in the same cavity of the first species, effectively parasitizing the parasitoid wasp (hyperparasitism). You can see the Sycoscapter females laying their eggs in the figs here with some outside predators in the midst.

But the adventure doesn’t stop there!

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Appolonius spp. (Rhyparochromidae: Drymini) bugs seen lurking around, possibly for a waspy snack.

Once I opened the figs, these tiny black  Appolonius spp. bugs  (Rhyparochromidae: Drymini) appeared. At first I mistook them for wasps as well based on their predatory-like behavior. Although I did not get a glimpse of them feeding on these wasps, I suspect they are predacious on the parasitoid wasps given previous observations on bugs eating wasps.

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No one is safe! Appolonius bug almost falls prey to a Green Tree Ant (Oecophylla smaragdina)

I feel incredibly lucky to be in Australia and witness complex interactions between insects like this. I hope you enjoyed peering into this figgy world! And yes, if you’ve eaten a fig, you’ve most likely eaten a wasp.

So there you have it: figs (Ficus variegata), pollinating fig wasps (Agaonidae), non-pollinating fig wasp parasitoids (Sycoscapter spp.), non-pollinating fig wasp hyperparasitoids (Watshamiella spp.), possibly predacious bugs (Appolonius spp.), and aggressive green tree ants (Oecophylla smaragdina). It’s a crowded bunch, but amazing to see the diversity of insects which can accumulate with a bountiful food source.

sycoscapter-spp1

For more insect adventures, follow my instagram: JustAnotherNakedApe

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