Evolution of toxicity in pitohuis: I. Effects of homobatrachotoxin on chewing lice (order Phthiraptera)

Birds in the genus Pitohui carry the potent neurotoxin homobatrachotoxin in their skin and feathers. In this study, I tested whether homobatrachotoxin can repel or kill chewing lice (order Phthiraptera). When individual feath er lice were offered a choice of two feathers on which to feed or take shel ter, the lice preferred nontoxic feathers to bathers of the most toxic pito hui species, Pitohui dichrous. Moreover, the presence of toxic P. dichrous feathers significantly shortened the life span of captive bather lice. Thes e results suggest that homobatrachotoxin repels and kills lice and may thus protect pitohuis against lice infestation.