The ant fauna of Rakitu (Arid Island), New Zealand

Abstract

Monitoring the fauna of an island before ecological restoration work begins provides a baseline against which changes to that environment can be quantified. Ants are a diverse and ecologically important group of insects, and many are extremely successful invasive species. In this study we provide the first description of the ant fauna of Rakitu (Arid Island), a small island in the outer Hauraki Gulf of New Zealand. We used a combination of unbaited pitfall traps, baited stations (rat traps with peanut butter) and hand searching conducted in habitats across the island. Using morphological classification and genetic barcoding we detected seven species of ant: four New Zealand endemics (Austroponera sp., Heteroponera brouni, Monomorium antarcticum, and Monomorium antipodum) and three introduced (Iridomyrmex suchieri, Ochetellus glaber, and Tetramorium grassii). While the ecological effects of these introduced species are currently unquantified, none of them have previously been highlighted as likely ecological threats. Our results provide a baseline for future biosecurity monitoring of the island, and can be used to help assess changes in the environment related to the forthcoming removal of invasive rat species from Rakitu