Studying the foraging and communication ecology of European fire ants

The European fire ant (EFA), or ruby ant, Myrmica rubra L., is an invasive pest in Greater Vancouver, British Columbia, Canada. EFAs are a nuisance to humans, swarming and stinging aggressively when nests are disturbed. They also cause ecological damage by altering invertebrate communities. The overarching goal of this thesis was to create a control method for EFAs. My specific research objectives were to: (1) develop an effective and affordable food bait; (2) determine trail following of EFAs in response to synthetic trail pheromone; and (3) determine trail following of ants in response to synthetic trail pheromone blends of multiple ant species. Food baits comprising diverse macronutrients such as carbohydrates (apples), proteins and lipids (dead insects) elicited the strongest foraging responses by EFAs. Re-hydrated freeze-dried baits proved as appealing as fresh baits and superior to rehydrated heat-dried baits. Isomerically pure and impure synthetic trail pheromone (3-ethyl-2,5-dimethylpyrazine) prompted similar recruitment responses of ants. The presence of pheromone, irrespective of dose tested, enhanced the recruitment of ants to food baits, with the dose of 200 ant equivalents eliciting the strongest recruitment responses. Trail pheromone applied in a line leading toward the food bait, but not in a circle surrounding it, was effective in recruiting ants, suggesting that 3-ethyl-2,5-dimethylpyrazine has a guiding but not an attractive function to EFAs. The presence of con- and hetero-specific pheromones had additive or indifferent effects on trail-following responses of garden ants, Lasius niger, and carpenter ants, Camponotus modoc, respectively. These data provide key information for the development of a highly functional insecticidal food bait for EFAs and other nuisance ant species.