Long-Term Field Trial to Control the Invasive Argentine Ant (Hymenoptera: Formicidae) With Synthetic Trail Pheromone

Abstract

Previous short-term experiments showed that trail following behavior of the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), can be disrupted by a high concentration of synthetic trail pheromone component (Z)-9-hexadecenal. In this study, a long-term field trial was conducted in 100-m2 plots of house gardens in an urban area of Japan to see whether the control effect on Argentine ants can be obtained by permeating synthetic trail pheromone from dispensers. The dispensers were placed in the experimental plots during the ant's active season (April-November) for 2 yr with monthly renewal. To estimate Argentine ant population density, foraging activity of Argentine ants in the study plots was monitored by monthly bait surveys. Throughout the study period, Argentine ant foraging activity was suppressed in the presence of the dispensers, presumably via trail forming inhibition. In contrast, the level of foraging activity was not different between treatment and no-treatment plots when the dispensers were temporarily removed, suggesting that treatment with pheromone dispensers did not suppress Argentine ant density in the treatment plots. Population decline may be expected with larger-scale treatment that covers a significant portion of the ant colony or with improvement in the potency of the disruptant.

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

“…While dominating untreated bait cards, Argentine ants arrived sporadically and in a more disorganized manner, when treated with synthetic pheromone. This is consistent with results in previous studies [38]–[41], which had reported that trail following behaviour of Argentine ants could be disrupted with synthetic pheromone. These studies provided a proof of concept for the pheromone disruption in Argentine ants by analysing trail integrity [38] and providing evidence for a negative impact on their foraging [39], [41].…”

“…This is consistent with results in previous studies [38]–[41], which had reported that trail following behaviour of Argentine ants could be disrupted with synthetic pheromone. These studies provided a proof of concept for the pheromone disruption in Argentine ants by analysing trail integrity [38] and providing evidence for a negative impact on their foraging [39], [41]. However, it was previously unclear whether this interference with Argentine ants recruitment actually translates into an effect on the resident ant community, which could be used to support native species.…”

“…Previous laboratory and field tests have demonstrated that the synthetic trail pheromone (Z)-9-hexadecenal (Z9-16:Ald) disrupts Argentine ant trail-following behaviour by interfering with track angles to reduce foraging success [38]–[41]. High pheromone concentrations prevent Argentine ants from establishing stable trails and recruiting to resources in the area [39], although existing heavy traffic requires more pheromone for disruption [40].…”

Pheromone-Assisted Techniques to Improve the Efficacy of Insecticide Sprays Against <I>Linepithema humile</I> (Hymenoptera: Formicidae)

“…Several studies have been conducted in Japan and Hawaii to test whether the application of synthetic (Z)-9-hexadecenal disrupted trail formation and foraging activity of Argentine ant populations in the Þeld (Suckling et al 2008(Suckling et al , 2010Tanaka et al 2009;Nishisue et al 2010;Sunamura et al 2011). Even relatively large quantities of synthetic (Z)-9-hexadecenal had a negligible impact on Argentine ant populations when used as a stand-alone treatment (Nishisue et al 2010), but produced a signiÞcant effect when used in conjunction with toxic baits separately applied in the Þeld (Sunamura et al 2011). Extermination of ants by the insecticidal bait coupled with inhibition of reinfestation by disruption of foraging by the applied (Z)-9-hexadecenal were attributed as possible mechanisms of the combination effect.…”

Thigmotaxis Mediates Trail Odour Disruption

“…Their heavy reliance on trail pheromones as a predominant mode of orienting and dominating a landscape 20 may also be their Achilles heel 21 . The use of the trail pheromone ( Z )-9-hexadecenal for Argentine ant management has recently been examined as an environmentally benign control method for this species 22–27 . Pheromone-based pest management offers the advantages of low-hazard and high target specificity, avoiding many unwanted off-target effects 28 .…”