Wasp and Ant Nests: Who Really Protects Whom? New Insights From Amazonian Forests

ABSTRACT Studies of animal behaviour are often biased towards species that are large‐bodied or have broad geographic ranges, as these are easier to observe in nature. Consequently, our understanding of behavioural ecology is shaped by such biases, even though these studies have provided important insights. Rarer or more cryptic behaviours, especially in historically neglected taxa, can nonetheless reveal key aspects of ecological and evolutionary dynamics. One such underexplored phenomenon involves nesting associations between social wasps and ants. Here we present the first photographic and video documentation of Agelaia pallidiventris nesting within a Azteca ant nest in the Brazilian Amazon. The wasps occupied chambers inside the ant nest through three circular openings, coexisting without visible aggression. The observation suggests a stable, possibly mutualistic association. This finding provides unprecedented evidence of an intimate wasp–ant nesting relationship and highlights the need for renewed natural history research. Understanding whether such interactions are commensal (e.g., where wasps gain passive protection from the ants' territoriality), parasitic (e.g., cleptoparasitism), or mutualistic (e.g., a defence system against shared predators) will illuminate the selective pressures shaping behavioural evolution in Amazonian insect communities.