Hunting habits die hard: Conserved prey preferences in neotropical army ants across distant neotropical rainforests

Supplemental dataset to article.

Article abstract: Army ants are widely recognized as keystone species in neotropical rainforests due to their role as important arthropod predators. Their large-scale raids involve countless workers scouring the forest floor in pursuit of prey, primarily capturing other invertebrates. However, our understanding of the precise dietary preferences and the degree of niche differentiation among sympatric species remains limited. In this study, we resolved an Ecuadorian army ant predation network consisting of 244 prey species and 13 army ant species of the genera Cheliomyrmex, Eciton, Labidus, Neivamyrmex, and Nomamyrmex. We collected 2,156 prey items from 180 army ant raids/emigrations, and of these, we identified 1,945 prey items to family level, 1,313 to genus level and 664 to species level based on morphological identifications and DNA barcodes. Prey consisted primarily of other ants (1,843 prey items; 153 ant species), to the largest part ant brood (N = 1,726). Hence, most army ant species chiefly plundered the nests of other ants, while the three swarm-raiding species, i.e. L. praedator, L. spininodes, and E. burchellii, exhibited a relatively high proportion of non-ant invertebrate prey in their diet. The predation network showed a high degree of specialization (H₂ˈ = 0.65), characterized by little dietary niche overlap among sympatric species. We compared the Ecuadorian network with one previously studied in Costa Rica and found that, despite the large geographic distance, prey preferences remained remarkably similar. We discovered species-specific preferences for captured ant genera and species, despite some species turnover in both army ants and prey. Additionally, army ants also exhibited consistent spatio-temporal raiding preferences across study sites. In conclusion, predation preferences within army ant communities exhibited consistency in multiple niche dimensions across two distant geographic regions, suggesting a notable level of predictability within army ant predation networks.