Abstract:
Introductions of ants into new areas can dramatically influence resident ant
populations. A recent ant introduction to New Zealand is the Australian
myrmicine, Monomorium sydneyense Forel. The effects of this ant on the
resident ant fauna of Tauranga were assessed, as well as the role of
temperature and food concentration on competitive dynamics. Aspects of
foraging characteristic and intraspecific behaviour were studied in order to
aid management decisions, should population control by toxic baiting be
required. There was a significant difference in community structure in M.
sydneyense invaded communities compared to uninvaded ones, although the
abundance of no individual species was significantly affected or was
displaced by M. sydneyense. Temperature was found to play a strong role in
the competitive dominance of M. sydneyense. Monomorium sydneyense
dominated a larger proportion of baits at warm temperatures, however it
secured significantly less foods at cooler temperatures. Temperature
preference trials in the laboratory supported field observations as M.
sydneyense displayed a preference for warmer temperatures, compared to
Pheidole rugosula Forel which showed no preference for any of the
temperatures tested. Monomorium sydneyense showed a distinct preference
for the protein based food resources that were offered, including the ant bait
X-Stinguish®. Foraging distance trials showed that M. sydneyense workers
were never observed foraging more than 2.8 m from their nest. The
probability of only 50% of baits being occupied by M. sydneyense at a
distance of 1 m from a nest suggests that intensive baiting would be required to manage populations of this ant, highlighting that the population
management of M. sydneyense would be difficult. Aggressive behaviour was
displayed between workers from different nests, suggesting that there is a
reduced likelihood of this ant attaining high population densities in New
Zealand.
