Predatory caddisfly larvae sequester tetrodotoxin from their prey, eggs of the rough-skinned newt (Taricha granulosa).

Caddisfly larvae (Limnophilus spp.) are important predators of eggs of the rough-skinned newt (Taricha granulosa). Newts may possess extremely large quantities of the neurotoxin tetrodotoxin (TTX) in their skin, and females may provision this toxin in their eggs. Using a competitive inhibition enzymatic immunoassay, we examined TTX-resistant caddisflies, sympatric with the known most toxic population of newts, for the presence of TTX. We found that caddisflies sequester TTX after consuming eggs in the laboratory. Caddisfly larvae that were frozen immediately after collecting in the wild possessed TTX. Finally, wild-caught larvae reared on a TTX-free diet in the laboratory retained TTX for up to 134 days, through metamorphosis and into the adult stage.