Document Type

Thesis

Degree

Master of Science

Major

Biology, Animal Behavior

Date of Defense

4-24-2015

Graduate Advisor

Godfrey R Bourne, PhD.

Committee

Dunlap, Aimee

Shaffer, Chris

Abstract

I studied the foraging ecology of a Neotropical leaf-cutter ant, Atta cephalotes, at CEIBA Biological Center, Guyana to elucidate diet choice and foraging strategy. These ants are serous agricultural pests because workers harvest leaves, flowers, fruits, and other plant organs of both cultivated and native plants. The plant materials are used to feed symbiotic fungi whose mycelia tips are the sole food of A. cephalotes larvae. Leaf-cutters were usually found in human disturbed habitats especially slash-and-burned forests cleared for farms, with their higher percentage of sun-exposure and lower plant stem diameters than second growth and primary forests. When given a choice of cultivated and wild plant leaves offered in a randomized smorgasbord test, leaf-cutters accepted significantly more cultivar leaves. These had lower concentrations of secondary compounds than wild plant leaves. In addition, leaf fragment size and thickness transported by returning foragers were related to the foragers’ body length, such that longer ants carried longer and thicker fragments compared to smaller ants. However, there was no relationship between travel distance to the nest and load size, recruitment and returning forager counts, or preference for cultivated plants as predicted by central place foraging theory. In summary, leaf-cutter ants at CEIBA Biological Center were found in human altered forest habitats, exhibited preferences for cultivated over wild plant organs, and did not conform to predictions of central place theory. Therefore, findings have implications for leaf-cutter ant behavioral ecology and agricultural management.

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