The Worm That Beat the Trap

Show notes

Welcome to the next episode of The Worm Podcast 🍄

Today we have predators, escape, genetics — and worms that literally rupture in water.

The predator is Arthrobotrys oligospora, a carnivorous fungus that builds adhesive networks capable of trapping nematodes.

But researchers asked a fascinating question:

can a worm evolve its way out of the trap?

🍄 Escaping a fungal predator

The team screened around 200,000 C. elegans genomes looking for mutants capable of crossing fungal traps without being captured.

Five particularly resistant strains emerged.

Wild-type worms were caught almost immediately. The resistant mutants achieved escape rates of around 40%.

And remarkably, all five pointed towards the same gene:

nhr-66.

🧬 The secret is in the skin

NHR-66 is a nuclear hormone receptor expressed in tissues responsible for producing the worm cuticle.

When nhr-66 was disrupted, expression of more than 1,200 genes fell dramatically.

Among the strongest effects were the cuticular collagens.

Around 40% of the worm’s collagen gene family was downregulated.

The fungal trap therefore appears to exploit something incredibly fundamental to the worm — the proteins forming its outer surface.

Restore those collagens and the worms become easier for the fungus to catch again.

The same resistant worms could also escape traps produced by several other Arthrobotrys species.

So why hasn't evolution simply produced worms without NHR-66?

💧 Then came the water

There is a catch.

Put the resistant nhr-66 worms into deionised water and their weakened cuticle becomes a serious liability.

Around 60% ruptured within just 10 minutes.

Escape the fungus — but become vulnerable to osmotic stress.

And when mutant and wild-type worms were placed together in soil, wild-type animals ultimately outcompeted the fungal-resistant mutants.

🧠 Evolution loves a trade-off

This is what makes the study particularly interesting.

Losing NHR-66 can provide a major advantage when facing a fungal predator.

But that advantage comes at the expense of the structural integrity needed to survive other environmental challenges.

It is a classic evolutionary compromise:

avoid being eaten × maintain a strong body

The best defence against one threat may create vulnerability to another.

🧠 The take-home message

A worm's cuticle is much more than armour.

It is part of a molecular interaction between predator and prey.

NHR-66 controls the collagen-rich surface that helps fungal traps grab the worm — but those same collagens help stop the worm from bursting when its environment changes.

Sometimes escaping your predator comes at a surprisingly high price.

📄 Paper discussed

Han-Wen Chang, Hung-Che Lin, Ching-Ting Yang, Rebecca J. Tay, Dao-Ming Chang, Yi-Chung Tung and Yen-Ping Hsueh (2025)

Cuticular collagens mediate cross-kingdom predator–prey interactions between trapping fungi and nematodes

PLOS Biology, 23(7): e3003178

DOI: https://doi.org/10.1371/journal.pbio.3003178

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If you would like your research discussed in a future episode of The Worm Podcast, please contact Dr Veeren Chauhan.

🔗 www.veerenchauhan.com
📧 veeren.chauhan@nottingham.ac.uk