Stable isotope analysis reveals a New Zealand alpine beetle's lichen diet

Abstract

Protodendrophagus antipodes beetles and their larvae live at high elevation in rock outcrops on mountains along New Zealand's Southern Alps. Living above the tree line, they require a different diet from their forest‐dwelling relatives that feed on fungi under loose bark. Stable isotope analysis of potential food sources revealed that the probable diet for P. antipodes was either, or both, of two species of ammonia‐absorbing lichens; one crustose and one fruticose species. The lichen diet is possibly unique among the family Silvanidae and is surprisingly rare globally among the hyper‐diverse beetle fauna.