Temperature and starvation effects on food exploitation by Argentine ants and native ants in New Zealand



Phil Lester, Centre for Biodiversity and Restoration Ecology, Victoria University of Wellington, PO Box 600, Wellington, New Zealand. E-mail: phil.lester@vuw.ac.nz


The abundance and distribution of an invasive species is influenced by its relative ability to find resources under a variety of conditions. We examined the exploitative ability of the Argentine ant (Linepithema humile (Mayr)), in comparison with two common New Zealand ant species Monomorium antarcticum (Fr. Smith) and Prolasius advenus (Hymenoptera: Formicidae) (Fr. Smith), using maze trials under different temperature and starvation regimes. Our results showed temperature significantly affected the mean time to discover food resources, but different species responded differently to changes in temperature. A change in temperature from 23°C to 13°C resulted in an approximately 8-fold increase in the time to discover food for native P. advenus, but discovery times remained relatively similar for invasive Argentine ants. Starvation did not significantly influence the ability of species to find food. Argentine ants consistently located and recruited to food faster than the native species. We examined for variation in walking speed under the experimental conditions as a mechanism for our results. The results revealed Argentine ants and P. advenus to have similar walking speeds at each temperature-starvation treatment and both were faster than M. antarcticum. However, Argentine ants had rates of turning or returning to the nest that were lower than the native species. This result suggests that Argentine ants show greater ‘exploratory willingness’ or ‘novelty seeking’ behaviour. Our results suggest that Argentine ants are able to discovery and exploit resources more efficiently than these native species under a wide spectrum of environmental and physiological conditions. Such relative efficiencies have likely contributed to the success of this invader.