Zhang, Y., Wang, Y., Li, P., Wanga, V.O. & Nakamura, A.

The enigma of sugar: changes in aggressiveness of weaver ants across habitats in response to sugar supplies

Arboreal ants are ecologically dominant in tropical forests due to their primarily herbivorous diet and aggressive behavior. This aggression is known to be influenced by the availability of carbohydrate and protein resources. However, how nutrient availability interacts with habitat variation to shape ant behavior remains poorly understood. Here, we investigated the trophic positions of the Asian weaver ant, Oecophylla smaragdina (FABRICIUS, 1775), and tested how carbohydrate supplementation affects their behavior across different habitat types in tropical Xishuangbanna, China. We hypothesized that weaver ants exhibit different trophic positions across habitats, influencing their activity and aggression, and that carbohydrate supplementation enhances these behavioral traits. To test these hypotheses, we collected weaver ants from a natural habitat (rainforest) and two types of plantations (agroforestry with rubber trees and fruit garden) for nitrogen and carbon stable isotope analyses. Behavioral responses were assessed by offering sucrose solution and distilled water (control) in each habitat. This study found that: 1) ants in the three habitats did not differ in trophic position, but their resource utilization varied; 2) ants in the fruit garden, where carbohydrates are likely less constrained, displayed lower foraging recruitments and reduced persistence at baits over time; and 3) short-term carbohydrate supplementation did not significantly alter ants‘ overall aggression across habitats, but reduced activity levels, including foraging recruitments and persistence at baits. These findings challenge previous assumptions that sugar feeding consistently enhances the aggression and activity of ants. Our results offer new insights into how carbohydrate availability modulates the behavior of ecologically dominant arboreal ants across different habitats, with implications for their ecological roles and potential applications in biological control.

Open access, licensed under CC BY 4.0. © 2026 The Author(s).

Aggressive behavior, weaver ant, habitat change, carbohydrate utilization, Hymenoptera, Formicidae