Abstract:
By determining if there is any temporal variation in toxic bait, carbohydrate and protein preference in Argentine and Darwin’s ants, we can provide better control options because we can identify with more accuracy when ants will be foraging for one food type over another. Improving our understanding is also fundamental as we can improve future bait formulations, bait application and timing, and increase levels of bait uptake. I have two aims in this thesis. First, I investigated toxic bait, carbohydrate and protein preferences for Argentine ants (Linepithema humile) and Darwin's ant (Doleromyrma darwiniana). The second aim in my thesis was to examine the efficacy of toxic baits in laboratory colonies of Argentine ants. Food preferences varied between species and within species considerably throughout the year, although Darwin's ant consistently favoured foods higher in carbohydrates. Argentine ants showed a significant preference for protein over carbohydrates during December and January. Despite differences in carbohydrate and protein preferences the preference for individual toxic baits showed little temporal variation. The toxic bait efficacy experiment revealed that Xstinguish™ and Exterm-an-Ant® baits produced the highest mortality rate. Other commercially available toxic baits had little effect on workers or queens. The efficacy of the toxic baits was influenced by the starvation level of the ant colonies, and only the colonies that were starved for 48 hours experienced a 100% mortality rate. Due to these results, I recommend that bait application with Xstinguish™ and Exterm-an-Ant® in late winter-spring would be optimal as this time frame is when ants are likely to be starved, and when foraging activity is increasing, thus maximising the chances of bait uptake. A second round of baiting treatment with both baits (Xstinguish™ and Exterm-an-Ant®) in summer when Argentine ants have been shown to undergo a second wave of reproduction could also be beneficial.
