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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Pest Management Research » Research » Publications at this Location » Publication #386861
Research Project: Forecasting, Outbreak Prevention, and Ecology of Grasshoppers and Other Rangeland and Crop Insects in the Great Plains

Location: Pest Management Research

Title: Navigating in paradise: unraveling use of a magnetic compass and path integration in Neotropical leaf-cutter ants

Author
item RIVEROS, ANDRE - Universidad Del Rosario, Columbia
item Srygley, Robert

Submitted to: Smithsonian Contributions to Botany
Publication Type: Book / Chapter
Publication Acceptance Date: 11/27/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Leaf-cutter ants harvest leaves, flowers, and fruits to grow a fungus upon which they rely for food. Their broad diets include many subtropical and tropical crops, which makes them an extremely important agricultural pest. Their foraging activity is also responsible for 17-20% of the nutrient turnover in Neotropical forests. Although the ants make chemically-marked and architecturally-modified trails that they follow between the nest and where they harvest leaves, they are also capable of path-integrating so that they orient toward home when removed from the trail. Path-integration (also known as dead reckoning) is a summation of directional and distance vectors, which is well known in desert ants Cataglyphis. When the sun is not visible, Atta use a magnetic compass to update their path-integrated vector home. When the sun is visible, the sun compass overrides directional information from the magnetic compass. Contact with soil is necessary for the leaf-cutter ants to develop a functioning magnetic compass. The leaf-cutter ants’ sensitivity to magnetic fields and the physical properties of its compass are useful for developing magnetic barriers to divert foraging trails from crops.

Technical Abstract: Leaf-cutter ants are famous organisms on Barro Colorado Island (BCI) recognized by their conspicuous nests, their highways-like foraging trails and their agricultural life histories. As farmers, leaf-cutter ants harvest plants to feed their subterranean cultivars of fungus. While foraging for leaves, fruits and petals, ants must navigate long intricate routes, primarily relying on chemical and physical trails as well as visual landmarks. Yet, nocturnal activity, risk of falling from trees, as well as washing of their chemical trails by rain, demand alternative backup mechanisms to navigate. We have aimed to unravel the use of a magnetic compass to navigate by updating a path-integrated home vector. Path integration is a well-known vector-based mechanism requiring tracking distances and directions while en route. Foraging at night in three-dimensional routes makes it the most challenging to path integrate. By experimentally manipulating the local magnetic fields and the ants’ magnetic compass, we have shown that the leaf-cutter ant Atta colombica is able to update its path integrator using a magnetic compass as well as proprioceptive information. Moreover, we have shown that contact with soil is required for the ants to develop a functional magnetic compass. Together, our results suggest that A. colombica navigates relying on multiple cues used in a hierarchical fashion. Leaf-cutter ants belong to the tribe Attini, including several species that forage solitarily and on vertical and horizontal surfaces. Therefore, our research sets the foundation for comparative studies on mechanisms of navigation in a highly complex environment.