Reconnaissance and latent learning in ants

Abstract

We show that ants can reconnoitre their surroundings and in effect plan for the future. Temnothorax albipennis colonies use a sophisticated strategy to select a new nest when the need arises. Initially, we presented colonies with a new nest of lower quality than their current one that they could explore for one week without a need to emigrate. We then introduced a second identical low quality new nest and destroyed their old nest so that they had to emigrate. Colonies showed a highly significant preference for the (low quality) novel new nest over the identical but familiar one. In otherwise identical experiments, colonies showed no such discrimination when the choice was between a familiar and an unfamiliar high-quality nest. When, however, either all possible pheromone marks were removed, or landmarks were re-orientated, just before the emigration, the ants chose between identical low-quality new nests at random. These results demonstrate for the first time that ants are capable of assessing and retaining information about the quality of potential new nest sites, probably by using both pheromones and landmark cues, even though this information may only be of strategic value to the colony in the future. They seem capable, therefore, of latent learning and, more explicitly, learning what not to do.

Why do not all workers work? Colony size and workload during emigrations in the ant Temnothorax albipennis

“…First, scout ants leave the nest to search for suitable new nest sites. In this search, prior knowledge of possible sites is taken into account (Franks et al 2007b). Once a scout has discovered a potential nest site, it assesses the site's quality and then starts to recruit to it with tandem runs, leading one recruit at a time (Möglich and Hölldobler 1974).…”

Seasonality in communication and collective decision-making in ants

“…Nest quality was varied by manipulating light levels within nests: bright nests let light in through their top slide, whereas dark nests were covered with cardboard to prevent light from entering the nest cavity. Temnothorax albipennis colonies consistently prefer dark over bright nests [31,32] and develop an aversion towards bright nests when housed in a dark nest [24,26]. Indeed, light levels within the nest are used by the ants as a proxy for the number and/or size of openings to the outside environment [31]; a nest with few, small openings (dark nest) is easier to defend and allows better protection from exterior conditions than a nest with many, large openings (bright nest).…”

“…nest-marking chemicals removed, removal) and (iii) positional cues conflicting with nest-marking chemicals (exchange). Collective aversion towards the familiar nest was induced as in previous studies [24,26]: colonies housed in a dark nest were allowed freely to visit and familiarize themselves with a bright nest during one week. Colonies were then induced to emigrate by removing the top glass slide and the cardboard perimeter of the old nest, and their preference between two equidistant nest sites was recorded (see below).…”

“…Accordingly, we investigated the decision-making mechanisms of T. albipennis colonies in summer, in autumn and in winter. More specifically, we aimed to identify the mechanisms responsible for the collective aversion towards familiar, low-quality nest sites previously reported in this species, as we suspected it might breach independent evaluation: colonies are known to gather information about available, low-quality nest sites while their own nest is intact, and later to avoid these sites when forced to emigrate [24][25][26]. We first evaluated the relative importance of positional versus chemical cues in nest-site selection at different times of year, and found that collective aversion towards low-quality nests is mediated by aversive nest-marking chemicals.…”

Memória predatória da aranha Argiope argentata: localização e tamanho da presa

“…Franks et al (2007) mostraram que as formigas podem efetuar trajetos de reconhecimento em seu ambiente e usar a informação obtida em trajetórias futuras. É algo semelhante à aprendizagem latente em ratos (um processo marcante no desenvolvimento da concepção cognitivista de aprendizagem).…”