Researcher Studying Presence, Effects of Brood Pheromone in Fire Ant Colonies in Food Selection
Brad Metz separating fire ants for study
Metz inspecting a brood of fire
ants for
a bioassay.
Fire ants near a food source in a
bioassay set up for study.
What does the foraging behavior of honey bees that are searching for pollen and nectar have to do with the foraging behavior of the red imported fire ant that is searching for protein (other insects) and carbohydrates? One researcher in Dr. Brad Vinson’s lab is trying to answer that question.
Dr. Brad Metz is trying to characterize the pheromone that helps communicate larval presence to the adults is present in fire ants. The idea came from his work as a Ph.D. student, conducting research on characterizing a brood pheromone within a honey bee colony. He said he thought that a similar pheromone may be present in fire ants. The brood pheromone in honey bees modifies the selection of which foods the bees should forage for to help the colony’s brood continue to grow.
The red imported fire ant research additionally aims to discover if the ants are using pheromones to regulate foraging habits of the adults to different food sources.
Similarly to the honey bee brood pheromone, he hypothesized that chemicals extractable from fire ant larvae would regulate colony level foraging behavior, optimizing foraging effort in response to the presences and/or state of the larvae.
Metz began by creating a bioassay in which foraging patterns, specifically ant traffic to and from food sources can be measured. Using separate trials for different food sources, he was able to observe relative foraging along well-delineated trails. Metz also found that ants tend to forage for protein at elevated numbers over time when brood is present or when larval cuticular extracts are added to fire ant colonies.
He noted that evidence is very clear that some of the ants exhibit different foraging habits when the brood is present compared to when the brood is absent from the test colonies.
Metz also looked at the larval stages of the fire ants and tested for free fatty acid esters, the class of chemicals of which honey bee brood pheromone is composed. He found that the larvae did have chemicals extractable from the cuticle that are similar to the components of brood pheromone of honey bees.
Metz said he will do further tests to identify the compounds present on the ant larvae and the compound proportions before declaring any similarity to the brood pheromone found in honey bees. In the future, Metz said if a compound is found and can be properly synthesized, it could potentially serve to modulate fire ant foraging patterns, and possibly serve as an attractant for baits and other fire ant control techniques.