Disruption of Foraging by a Dominant Invasive Species to Decrease Its Competitive Ability

Abstract

Invasive species are a major threat to biodiversity when dominant within their newly established habitat. The globally distributed Argentine ant Linepithema humile has been reported to break the trade-off between interference and exploitative competition, achieve high population densities, and overpower nests of many endemic ant species. We have used the sensitivity of the Argentine ant to the synthetic trail pheromone (Z)-9-hexadecanal to investigate species interactions for the first time. We predicted that disrupting Argentine ant trail following behaviour would reduce their competitive ability and create an opportunity for three other resident species to increase their foraging success. Argentine ant success in the control was reduced with increasing pheromone concentration, as predicted, but interactions varied among competing resident species. These behavioural variations provide an explanation for observed differences in foraging success of the competing resident species and how much each of these individual competitors can increase their foraging if the competitive ability of the dominant invader is decreased. The mechanism for the observed increase in resource acquisition of resident species appears to be a decrease in aggressive behaviour displayed by the Argentine ant, which may create an opportunity for other resident species to forage more successfully. Our demonstration of species interactions with trail pheromone disruption is the first known case of reduced dominance under a pheromone treatment in ants.

Synthetic pheromones as a management technique – dispensers reduce Linepithema humile activity in a commercial vineyard

“…High pheromone concentrations prevent Argentine ants from establishing stable trails, thus limiting their ability successfully to forage and recruit greater numbers of conspecifics to resources in the area . Additionally, this treatment can also provide a competitive advantage for other resident ant species to increase their foraging, when directly competing with the Argentine ant for a specific food resource . Therefore, the potential exists for this synthetic trail pheromone to provide a management technique that, if successful, could reduce the risk of disruption to mealybug biological control and in doing so reduce the risk of plant pathogen spread.…”

Toxicity and utilization of chemical weapons: does toxicity and venom utilization contribute to the formation of species communities?

“…Alternatively, it is possible that not all species elicit the same strong aggressive response from Argentine ants. In a previous experiment, we showed that Argentine ants react differently to competitors in field experiments and may chose to ignore or avoid some species if met under natural conditions (Westermann et al 2014).…”

“…In a previous experiment, we showed that Argentine ants react differently to competitors in field experiments and may chose to ignore or avoid some species if met under natural conditions (Westermann et al. 2014). …”

Larval Pheromone Disrupts Pre-Excavation Aggregation of Cactoblastis cactorum (Lepidoptera: Pyralidae) Neonates Precipitating Colony Collapse

“…Choe et al (2014) obtained similar results by mixing trail pheromone with an insecticide. Studies by Westermann et al (2014) suggested that long term disruption of foraging behavior of the Argentine ant with a synthetic trail pheromone might reduce their competitive ability, leading to collapse of populations in favor of less harmful, indigenous species. However, the difficulty of achieving significant control of ants by any of these techniques is attributable to the fact that colonies of ants are not fully dependent on their communal trail system for survival, but also can search independently and orient directly to food odors (Suckling et al 2010a).…”