Load capacity of workers of atta robusta during foraging (Hymenoptera: Formicidae)

Abstract

Worker ants are highly polymorphic in the genus Atta and they are usually classified into castes according to the specific functions they perform in a colony. Minor workers (head width ≤ 2.0 mm) help to maintain and grow the symbiotic fungus whereas larger workers (head width > 2.0 mm) cut and transport plant fragments. This study investigated the roles in the cutting and transporting of different plant resources of different Atta robusta worker classes that were classified based on the size of their head capsule. Experiments were conducted in the restinga of Grussaí/Iquipari, São João da Barra, Rio de Janeiro State, Brazil. In each month between October 2009 and September 2010, we collected 100 ants and their respective loads from the trails of four nests of Atta robusta. The samples were individually transported to the laboratory, where the ants and their loads were weighed and the head capsules of the ants were measured. Large ants transported heavier loads. These ants usually transported more fruit and seeds than smaller ants.