The potential distribution of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), in New Zealand

Abstract

Red imported fire ants, Solenopsis invicta Buren, are not established in New Zealand but are considered to have a very high likelihood of introduction and establishment. The potential distribution of S. invicta in New Zealand was modelled using four different approaches: ecological niche modelling, climate matching, growing degree days, and by determining the time available for optimal foraging activity. Consensus of these modelling approaches show that environmental conditions most suitable for S. invicta establishment are areas of Northland and Auckland. Parts of the Waikato, coastal Bay of Plenty, Hawke's Bay and Gisborne may be suitable for founding colonies, but it is unclear whether these regions would allow the longer term establishment of S. invicta. A small number of locations around Nelson and Marlborough are possibly suitable for the establishment of S. invicta but other regions of the North Island and the South Island are unsuitable. The major constraint for S. invicta in New Zealand is the relatively low summer temperatures that severely limit the colony development and foraging activity of S. invicta. As a consequence, it appears that S. invicta would have a relatively restricted distribution in New Zealand. Further progress in assessing potential “invasive” species must more fully encompass the characteristics of the recipient community, including the role of, and interaction between, climate, distribution and abundance.