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AbstractHoney bees exhibit remarkable visual learning capacities, which can be studied using virtual reality (VR) landscapes in laboratory conditions. Existing VR environments for bees are imperfect as they provide either open-loop conditions or 2D displays. Here we achieved a true 3D environment in which walking bees learned to discriminate a rewarded from a punished virtual stimulus based on color differences. We included ventral or frontal background cues, which were also subjected to 3D updating based on the bee movements. We thus studied if and how the presence of such motion cues affected visual discrimination in our VR landscape. Our results showed that the presence of frontal, and to a lesser extent, of ventral background motion cues impaired the bees’ performance. Whenever these cues were suppressed, color discrimination learning became possible. We analyzed the specific contribution of foreground and background cues and discussed the role of attentional interference and differences in stimulus salience in the VR environment to account for these results. Overall, we show how background and target cues may interact at the perceptual level and influence associative learning in bees. In addition, we identify issues that may affect decision-making in VR landscapes, which require specific control by experimenters.

Angiosperms have evolved to attract and/or deter specific pollinators. Flowers provide signals and cues such as scent, colour, size, pattern, and shape, which allow certain pollinators to more easily find and visit the same type of flower. Over evolutionary time, bees and angiosperms have co-evolved resulting in flowers being more attractive to bee vision and preferences, and allowing bees to recognise specific flower traits to make decisions on where to forage. Here we tested whether bees are instinctively tuned to process flower shape by training both flower-experienced and flower-naïve honeybee foragers to discriminate between pictures of two different flower species when images were either normally configured flowers or flowers which were scrambled in terms of spatial configuration. We also tested whether increasing picture contrast, to make flower features more salient, would improve or impair performance. We used four flower conditions: (i) normally configured greyscale flower pictures, (ii) scrambled flower configurations, (iii) high contrast normally configured flowers, and (iv) asymmetrically scrambled flowers. While all flower pictures contained very similar spatial information, both experienced and naïve bees were better able to learn to discriminate between normally configured flowers than between any of the modified versions. Our results suggest that a specialisation in flower recognition in bees is due to a combination of hard-wired neural circuitry and experience-dependent factors.

Ants exhibit impressive olfactory learning abilities. Operant protocols in which ants freely choose between rewarded and nonrewarded odours have been used to characterise associative olfactory learning and memory. Yet, this approach precludes the use of invasive methods allowing the dissection of molecular bases of learning and memory. An open question is whether the memories formed upon olfactory learning that are retrievable several days after training are indeed based on de novo protein synthesis. Here, we addressed this question in the ant Camponotus fellah using a conditioning protocol in which individually harnessed ants learn an association between odour and reward. When the antennae of an ant are stimulated with sucrose solution, the insect extends its maxilla–labium to absorb the solution (maxilla–labium extension response). We differentially conditioned ants to discriminate between two long-chain hydrocarbons, one paired with sucrose and the other with quinine solution. Differential conditioning leads to the formation of a long-term memory retrievable at least 72¿h after training. Long-term memory consolidation was impaired by the ingestion of cycloheximide, a protein synthesis blocker, prior to conditioning. Cycloheximide did not impair acquisition of either short-term memory (10¿min) or early and late mid-term memories (1 or 12¿h). These results show that, upon olfactory learning, ants form different memories with variable molecular bases. While short- and mid-term memories do not require protein synthesis, long-term memories are stabilised via protein synthesis. Our behavioural protocol opens interesting research avenues to explore the cellular and molecular bases of olfactory learning and memory in ants.

Three-dimensional digital atlases are rapidly becoming indispensible in modern biology. We used serial sectioning combined with manual registration and segmentation of images to develop a comprehensive and detailed three-dimensional atlas of the honeybee head-neck system. This interactive atlas includes skeletal structures of the head and prothorax, the neck musculature, and the nervous system. The scope and resolution of the model exceeds atlases previously developed on similar sized animals, and the interactive nature of the model provides a far more accessible means of interpreting and comprehending insect anatomy and neuroanatomy.

The honeybee waggle dance, through which foragers advertise the existence and location of a food source to their hive mates, is acknowledged as the only known form of symbolic communication in an invertebrate. However, the suggestion, that different species of honeybee might possess distinct 'dialects' of the waggle dance, remains controversial. Furthermore, it remains unclear whether different species of honeybee can learn from and communicate with each other. This study reports experiments using a mixed-species colony that is composed of the Asiatic bee Apis cerana cerana (Acc), and the European bee Apis mellifera ligustica (Aml). Using video recordings made at an observation hive, we first confirm that Acc and Aml have significantly different dance dialects, even when made to forage in identical environments. When reared in the same colony, these two species are able to communicate with each other: Acc foragers could decode the dances of Aml to successfully locate an indicated food source. We believe that this is the first report of successful symbolic communication between two honeybee species; our study hints at the possibility of social learning between the two honeybee species, and at the existence of a learning component in the honeybee dance language.

Honigbienen (Apis mellifera L.) sind in der Lage mit ihren Komplexaugen visuelle Muster wahrzunehmen und die Musterinformation im Zentralen Nervensystem zu speichern und für Ähnlichkeitsbewertungen wieder abzurufen. Die vorliegende Arbeit zeigt klare Evidenz gegen eine ausschließliche Bewertung von Schwarzweißmustern mit Hilfe von Template-Matching-Mechanismen. Mit systematisch abgewandelten Dressurparadigmen trainierte Bienen bewerteten Muster unabhängig von der erfolgten Dressur stets bevorzugt gemäß eher grober Mustereigenschaften, wie zum Beispiel die Parameter "schwarzer Musterzentralbereich" und "Musterzerstreutheit". Veränderte man in einem weiteren Versuchansatz die Musterinformation der Schwarzweißmuster zudem gezielt durch geeignete Fourier-Filterung, zeigte sich, dass Bienen zur Musterdiskriminierung bereits die Frequenzinformation von 2 - 8 Schwingungen/Bildbreite genügte. Diese Unschärfe der bewerteten Bildinformation ließ sich nicht ausschließlich aus den optischen Eigenschaften des visuellen Apparates der Bienen ableiten. Videodokumentationen und Einzelbildanalyse des Flugverhaltens der Bienen vor den Mustern ergaben zudem keinerlei Hinweise für eine Nutzung des Flugverhaltens als Bewertungsgrundlage zur Musterdiskriminierung. Die erhaltenen Ergebnisse zur Musterdiskriminierung wurden vor dem Hintergrund eines ökonomischen Entscheidungsmodells für menschliches Verhalten, den Frugalheuristiken, diskutiert und Hinweise auf eine ökonomische Bewertungsstrategie der Bienen entsprechend einer Take-The-Best-Heuristik gefunden., Honeybees (Apis mellifera L.) are able to perceive visual patterns through their compound eyes and store the visual information in the central nervous system for subsequent use in pattern discrimination tasks. This thesis provides clear evidence against the assumption that pattern discrimination relies exclusively on template matching mechanisms. Bees discriminated pairs of patterns preferential using extracted pattern parameters. Within this thesis the preferred parameters of the bees following the training paradigms were coarse parameters such as "black centre" and "pattern disruption". In experiments with Fourier filtered patterns the frequency information of the patterns were additionally reduced. The results showed that bees could discriminate patterns using only 2 - 8 cycles/pattern-width of the frequency information. The fuzziness of the exploited visual information could not be assigned to restrictions of the visual system of bees. Additional documentation and single picture analysis of the videotaped flight behaviour in front of the patterns provided no evidence for bees using their flight behaviour in order to enhance the pattern discrimination ability. Application of economic human decision models (frugal heuristics) to the behavioural results showed clues that bees'' decisions could be explained with the help of the Take-The-Best-heuristic.

Beschrijving van het leergedrag van honingbijen en van de bouw en werking van de hersenen. Aan het leergedrag liggen twee belangrijke principes ten grondslag: olfactorische conditionering van de tongreflex, en visuele conditionering op basis van kleur, vorm en patroon. De aansturing van de verschillende gedragspatronen is gebaseerd op een drietal algemene principes in de opbouw van de hersenen: doelspecifieke neuronen (zenuwcellen), doelspecifieke neuropiles, en integratiecentra van hoge orde. Van deze drie organisatieniveaus in de hersenen worden voorbeelden beschreven (resp. het VUMmx 1 neuron, de antennelob, en de 'mushroom bodies'). Eerste van een serie van twee artikelen, vertaald door M. Boerjan uit Bee World 84(1)5-18 (2003)

UItleg over de algemene opbouw van de bijenhersenen, die erop gericht is om complexe processen te kunnen leren. De architectuur van deze 'leerhersenen' bestaat uit een complex netwerk van met elkaar verbonden modules (zenuwcellen of neuronen, neuropiles, en integratiecentra van hogere orde). De antennelobben zijn de primaire geur (olfactory) neuropiles, en bestaan uit verschillende bolvormige structuren (glomeruli) waarin de neuronen gelegen zijn die de signalen van de zintuigcellen opvangen en doorgeven aan de integratiecentra. Het specifieke activiteitenpatroon van de glomeruli als reactie op verschillende prikkels kan zichtbaar worden gemaakt met kleurstoffen. Tweede van een serie van twee artikelen, vertaald door M. Boerjan uit Bee World 84(1)5-18 (2003)