Ecology and taxonomic identification of āwheto | vegetable caterpillar in Hawke’s Bay, Aotearoa | New Zealand

Āwheto, also known as the vegetable caterpillar, is a taonga (treasure) of Aotearoa | New Zealand, produced when endemic Ophiocordyceps fungi infect ghost moth (Hepialidae) larvae and produce fruiting bodies extending from the infected larvae to above the forest floor. Despite its cultural importance, āwheto ecology is not well documented or understood. Partnering with kaitiaki (guardians), we paired mātauranga (Māori knowledge)-informed soil DNA assays with systematic field surveys to resolve āwheto ecology in a montane native forest. ITS2/18S gene metabarcoding detected Ophiocordyceps sequences in 92% of random soil samples, however āwheto were found in higher density clustered at a subset of three of these sites (and at 25% of randomly sampled sites). Āwheto occurred exclusively in tall red-beech (Fuscospora fusca) forest with partial canopy (c. 75%), deep litter, high bryophyte cover, and minimal bare ground (< 10%). Indicator analysis highlighted pōkākā (Elaeocarpus hookerianus) and Hall’s tōtara (Podocarpus laetus) as positive associates; occurrence was also more likely in west facing higher altitude sites. Sanger sequencing of stromata and moth larvae cadavers was used to identify Ophiocordyceps robertsii and its sole host, Dumbletonius unimaculatus, with low intraspecific genetic variation. Stroma persisted for > 10 months; motion-detection camera monitoring showed frequent deer visits caused negligible disturbance. These findings demonstrate that, although O. robertsii is widespread in soil, successful āwheto formation depends on specific micro-habitats and host distribution. Integrating molecular detection with mātauranga Māori offers a reliable, non-invasive tool for locating āwheto and provides a baseline for kaitiakitanga-led conservation.