Can communication disruption of red imported fire ants reduce foraging success

Authors: SUCKLING, D - NEW ZEALAND INSTITUTE OF PLANT & FOOD RESEARCH; STRINGER, L - NEW ZEALAND INSTITUTE OF PLANT & FOOD RESEARCH; JIMENEZ-PEREZ, A - NATIONAL POLYTECHNIC INSTITUTE; BUNN, B - NEW ZEALAND INSTITUTE OF PLANT & FOOD RESEARCH; Vander Meer, Robert - Bob

Submitted to: Myrmecological News
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2015
Publication Date: 3/8/2016
Citation: Suckling, D.M., Stringer, L.D., Jimenez-Perez, A., Bunn, B., Vander Meer, R.K. 2016. Can communication disruption of red imported fire ants reduce foraging success. Myrmecological News. 23:25-31.

Interpretive Summary: Imported fire ants cause over 6 billion dollars in annual control and damage costs in the United States and they are becoming a world-wide invasive pest ant. They infest Australia, Taiwan, China, Mexico and many Caribbean Island countries. Fire ant control relies on toxic drenches or baits that are bad for the environment and also affect non-target ant species. There is a need for biologically-based control methods, such as use of fire ant pheromones. To date suggested uses of pheromones for pest ant control have focused on making baits better. However, scientists at the Center for Medical, Agricultural and Veterinary Entomology, USDA, ARS, Gainesville, Florida USA, and the New Zealand Institute for Plant & Food Research Limited, Christchurch, New Zealand, collaborated to evaluate the effects of point longitudinal sources of the fire ant recruitment orientation pheromone, Z,E-'-farnesene, on the ability of fire ants to discover and remove food baits and maintain recruitment trails to food resources. We found that only about 50% of the fire ants trailing past point sources of recruitment pheromone on filter paper were were able to find the food source, whereas 100% of the untreated controls found the food resource. In addiiton, recruitment pheromone treatment significantly disrupted trail integrity. Disrupting fire ant recruitment to resources on a large scale is expected to have negative effects on resource collection, colony size, colony migration, and other effects yet to be determined. Further research is needed to establish the long-term effects and control potential for trail disruption in S. invicta, as well as to develop inexpensive synthetic methods for the trail pheromone.

Technical Abstract: Invasive pest ants often coordinate resource retrieval and colony expansion through the use of recruitment pheromones for information sharing to optimise their foraging; we argue that the potential for disruption of trail pheromone communication deserves investigation as a new and benign ecologically-based control method against ants. Monogyne red imported fire ant nests trailing to and feeding on thawed cricket were presented with disruptive upwind trail pheromone sources and their behaviour recorded. Pheromone sources were either 300 µg point sources or linear sources at 5.5 µg/cm of Z,E-a-farnesene. Ant behaviour was recorded from above and digitised. Ants trailing on a 10 ng/cm synthetic trail of Z,E-a-farnesene past an upwind source of the same synthetic trail pheromone took 2.4-fold (single release points) or three-fold (linear source) longer to discover the bait and remove it, than trailing ants without the communication disruption treatment present. About half the fire ants trailing past the linear sources of trail pheromone upwind (48%) were prevented from arrival at the food compared to untreated controls (100% arrival), and ant trails had significantly lower trail integrity, measured as r2, both towards the food and when returning to the nest. The less than complete drop in arrival was evidently partly due to the ability of the ants to recover their sensory system and distinguish their trail pheromone in clean air. A few ants were able to detect and follow low concentration synthetic trails despite exposure seconds earlier to 550-fold greater pheromone concentration sources which were behaviourally-disruptive. Trail pheromone disruption of fire ants appears to have potential if molecular analogues with longer lasting effects can be developed, but control using this method will be very challenging without a low cost commercial supply of disruptants. Progress is needed in both areas if trail pheromones are to be used widely. Structure-activity studies and biorational design of suitable molecules to overcome trail pheromone sensitivity at the olfactory receptor neuron level would appear warranted as a next step.