Chemically based interactions and nutritional ecology of Labidus praedator (Formicidae: Ecitoninae) in an agroecosystem adjacent to a gallery forest

Abstract

New World army ants species have an important role in structuring invertebrate communities. Labidus praedator (Fr. Smith, 1858) is a generalist top predator that can reduce pest densities in agroecosystems. The aim of this study was to describe behavioral attributes, diet composition and interspecific interactions of the ant L. praedator. We searched for army ant raids using standardized trail-walk surveys and plotted army ants raids positions on an aerial image. We photographed events at swarm raids of L. praedator and recorded its diet items in basal columns near bivouacs. Six species from four Ecitoninae genera - Labidus (Jurine, 1807), Nomamyrmex (Borgmeier, 1936), Neivamyrmex (Borgmeier, 1940) and Eciton (Latreille, 1804) - were recorded. Caterpillars dominated the composition of the diet of L. praedator. Flowers and diaspores of weeds and aril and flesh of fruits were also transported to bivouacs. One colony stopped foraging after intense rainfall and discrete groups of hundreds of L. praedator ants were separated under patches covered by shrubs. Groups of Crotophaginae birds, Sarcophaginae flies and Polistinae wasps followed L. praedator swarm raids. We discuss the importance of landscape structure for agroecosystem colonization by Ecitoninae and the existence of chemical opportunism between army ants species through the reuse of unoccupied trails.

Generic revision of the ant subfamily Dorylinae (Hymenoptera, Formicidae)

“…The bivouacs are found in rotten logs or are subterranean, occupying preformed cavities such as abandoned nest chambers of Atta leaf-cutting ants (Rettenmeyer 1963, Monteiro et al 2008). Mature colonies have been estimated to contain up to a million individuals (Fowler 1979).…”

“…Labidus forages in swarm raids similar to those of Eciton burchellii (Rettenmeyer 1963) and its species are even more generalized predators that in addition to ant brood will take a variety of other arthropods, sugar, and plant parts, including flowers, seeds, fruit, and even processed food such as boiled rice (Borgmeier 1955, Monteiro et al 2008). The two best-studies species, Labidus coecus and Labidus praedator , are similar in this respect and data on other species is lacking.…”

Opportunistic predation of a colony of Polybia platycephala (Richards) (Hymenoptera, Vespidae) by Labidus praedator (Smith) (Hymenoptera, Formicidae)

“…Although Rettenmeyer (1963) states that L. praedator shows strong preference for plant matter, these ants are usually observed carrying a mixture of ants and other arthropods, including spiders, scorpions, cockroaches and isopods, demonstrating diet plasticity (Monteiro et al, 2008;Powell & Baker, 2008).…”

“…It is important to note that prey of Labidus are mostly species that occur in the soil, with some individuals being able to forage at a height ofup to 130cm (Monteiro et al, 2008). For this reason, the reports about army ant attacks on social wasps are opportunistic and occasional, as in the work of Monteiro et al (2008) who, in addition to foraging time, also recorded a social wasp trying to seize a caterpillar that was being transported by ants and ended up being preyed upon by them.…”

“…For this reason, the reports about army ant attacks on social wasps are opportunistic and occasional, as in the work of Monteiro et al (2008) who, in addition to foraging time, also recorded a social wasp trying to seize a caterpillar that was being transported by ants and ended up being preyed upon by them. O'Donnell and Jeanne (1990), in Costa Rica, reported an attack on a colony of Agelaia yepocapa (Richards, 1978) located in the hollow of a tree trunk, facilitating the chance meeting by the ants.…”