Researchers carried out a study with ants offering them bait with caffeine and were able to observe that those who ingested the substance were able to learn faster the path to other rewards than those they did not consume.
The study was carried out with 142 insects and each of them was tested four times. Scientists recorded a 28% improvement in the efficiency of traveling to the desired location when using low doses of caffeine and 38% with an intermediate amount of the substance. The intention is to use this strategy to improve the effectiveness of controlling Argentine ants, considered an invasive species.
This variety of insect — Linepithema humile — is classified as a pest because it invades spaces and attacks sweet substances such as meat, bread and fruit. Furthermore, they harm plants, both ornamental and fruit-bearing, as they eat vegetation secretions and protect against aphids and mealybugs.
The results of the caffeine study were published in the journal iScience and the team of researchers began the project wanting to improve the efficiency of poison baits for this type of ant. To do this, they based themselves on the fact that the substance had already been tested on bees and drones, which also showed an improvement in learning with consumption.
“We are trying to get them to be better at finding these baits, because the faster they go back and forth, the more pheromone trails they leave, the more ants will come, and therefore the faster they will spread the poison in the colony before they realize it is poison. ,” said Henrique Galante, a computational biologist at the University of Regensburg in Germany.
Three different doses
In high amounts of caffeine, no differences in the behavior of ants were recorded, only in low and intermediate doses.
In the tests, the insects walked across a Lego bridge to a platform — made from a sheet of A4 paper on an acrylic surface — where researchers placed a drop of sucrose solution mixed with caffeine. The leaf was removed after ingesting the compound so that the ants could not follow their own pheromone trail back to the reward location.
“The lowest dose we use is what you find in natural plants, the intermediate one is similar to what you would find in some energy drinks and the highest amount is defined as the LD50 [dose letal] of bees — where half of these insects fed this amount die. So it is likely to be quite toxic for them”, says Galante.
The ants did not make the journey faster after ingesting the substance, but they were more efficient in finding their way to the next reward. This suggests that caffeine improved their ability to learn the route they should follow.
Extremely happy to share the second chapter of my PhD is officially out in iScience! https://t.co/a06MMjzs3H
— Henrique Galante (@GoSocialAnts) May 23, 2024
With the findings, scientists hope to help in efforts to control Argentine ants. More tests are being carried out in an open environment in Spain and, in future studies, the team would like to investigate the possible interaction between caffeine and the poison in the bait.
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