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Defensive Fungal Symbiosis in Stink Bugs

1:21:36 recording · AUTO · 2 speakers

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Brief overview

Japanese stink bug mothers farm fungi on their hind legs and smear them over eggs, blocking parasitic wasps.

  1. Hearing organs are actually fungus gardensThe tympanal-looking pads on mature females' hind legs are mycangia with about 2,000 secretory pores.
  2. The fungal coat is a physical barrierWasps struggle to push an ovipositor through the hairy hyphae, as with naturally hairy cutworm eggs.
  3. Field work reset the lab storyRemoving the fungus mattered for a second parasitic wasp species, not the one they started the work with.
Executive Summary AI
  • On Twevo 123, recorded February 25th, 2026, Vincent Racaniello and Nels Elde take up a Science Magazine paper on defensive fungal symbiosis on insect hind legs, from co-first authors Takanora Nishino and Minoru Moriyama with senior author Takima Fukatsu in Japan.15:20
  • The bugs belong to the Dinodoridae, a stink bug family with at least a hundred species and 16 genera, and what look like tympanal (hearing) organs on the hind legs of mature females turn out to be mycangia, roughly 2,000 pores that feed a luxuriant growth of fungal hyphae.26:42
  • Egg-laying females scratch those hind legs across their freshly laid rows of eggs, smearing the fungi on so the hyphae grow out by day three, which is vertical transmission that disappears again as the nymphs develop.31:07
  • Sampling different places in Japan turned up 600 different fungal isolates, sequenced and mostly non-pathogenic Cordyceps relatives, with each female carrying multiple fungal species whose composition matches what she puts on her eggs.40:22
  • A field study that took 12 years and began in 2014 showed a third of egg masses eaten by snails and about 20% parasitized by wasps, with cleaned-off eggs faring worse, though the wasp that mattered in nature was a second species that only showed up a year ago.55:02
Key Quote
“And the problem is then when you want to make a new sweater, there's nobody left who knows how to knit.”
— Vincent Racaniello9:52
Key Quote
“so by the way now this is this is gain of function, gain of fungus.”
— Vincent Racaniello39:43
Key Quote
“And I think it's important to remember that this thing could still go off the rails, right?”
— Nels Elde47:19