C. M. S. Plowright

Time estimation by pigeons on a fixed interval: the effect of pre-feeding.

Pigeons well trained on a fixed interval 10-s schedule of reinforcement were tested on the peak procedure. In a successive conditions design, they were either pre-fed or not in the experimental setting. Pre-feeding decreased the rate of responding. It also led to a maximum rate of responding that occurred 2-3 s later than in the control condition, where the maximum occurred at the usual time of reinforcement. The shift in peak time in response to pre-feeding shows that peak time may not be a pure measure of timing. The results are also interpreted in terms of timing theories.

Bumblebees occupy: when foragers do and do not use the presence of others to first find food

The aim of this study was to determine whether an unlearned preference by bumblebees for flowers that are occupied by other bees is frequency dependent and whether it depends on the size of the flower. In three experiments, bees leaving their colony for the first time were given 20 unrewarded choices of occupied versus unoccupied floral patterns in a radial arm maze. In Experiment 1, the relative frequency of occupiers was manipulated. In Experiment 2, a variety of large (≥6xa0cm diameter) artificial flowers was used. In Experiment 3, floral patterns were eliminated in an effort to reduce the similarity between “occupied” and “unoccupied”. A significant unlearned preference was found only under the combination of conditions in which occupied flowers were comparatively rare and the occupier to flower size ratio was relatively high. Otherwise, the preferences were non-significant, though the stimuli were discriminable because control groups given prior discrimination training acquired a preference. Our results narrow down the conditions under which foragers respond to the presence of others when making their first floral choices.

Foraging for nectar and pollen on thistle flowers (Cirsium vulgare) and artificial flowers : How bumble bees (Bombus impatiens) respond to colony requirements

This study documented two behavioural responses to pollen and nectar deprivation in a colony of bumble bees: flower handling and choice. In two laboratory experiments, colonies were deprived, on successive days, of pollen and of nectar. In the first experiment, the bees foraged on thistle flowers, and in the second, they foraged on artificial flowers. In both studies, flower handling depended on deprivation condition: the relative frequency of scrabbling for pollen rather than probing for nectar was of the order of tenfold higher when the colony was deprived of pollen. Choice also depended on deprivation condition. In Experiment 1, old thistle flowers, which had abundant pollen visible, were visited more frequently than new flowers when the colony was deprived of pollen. Similarly in Experiment 2, the row of artificial flowers containing both nectar and pollen was visited more frequently than the row of flowers containing only nectar when the colony was deprived of pollen.

Getting to the start line: how bumblebees and honeybees are visually guided towards their first floral contact

Much of the literature on foraging behaviour in bees focuses on what they learn after they have had rewarded experience with flowers. This review focuses on how honeybees and bumblebees are drawn to candidate food sources in the first place: the foundation on which learning is built. Prior to rewarded foraging experience, flower-naïve bumblebees and honeybees rely heavily on visual cues to discover their first flower. This review lists methodological issues that surround the study of flower-naïve behaviour and describes technological advances. The role of distinct visual properties of flowers in attracting bees is considered: colour, floral size, patterning and social cues. The research reviewed is multi-disciplinary and takes the perspectives of both the bees and the plants they visit. Several avenues for future research are proposed.

Mirror image pattern matching by bumble bees

Bumble bees (Bombus impatiens) were trained to discriminate between a rewarding and non-rewarding artificial flower that differed only in their configuration of four identical petals. On choice tests between 2 empty flowers, the bees chose the flower with the configuration of the rewarding flower over the mirror image, but the mirror image over a novel flower. This behaviour is the same as has been observed with honey bees and functional interpretations are considered. The problem of distinguishing between left-right pattern reversals and true mirror image transformations is discussed.

Assessment of pattern preferences by flower-naïve bumblebees

Two methods for the assessment of preferences by flower-naïve bumble bees (Bombus impatiens) were compared. Bees with and without prior experience on rewarding patterns were given twenty choices of unrewarding patterns (radial vs. concentric) in a radial arm maze. Either way, a preference for radial patterns was obtained. Prior training on grids of circles, squares or diamonds amplified the preference, whereas training on a ring of circles did not. Prior rewarded experience does not merely draw the bees’ attention to the patterns in the maze, or serve as a motivator, but also likely leads to a similarity judgment between training and testing. Given that it was possible to test for the choices of truly flower-naïve bumblebees, training is at best unnecessary and is at worst a source of bias.ZusammenfassungMit diesen Untersuchungen bei Hummeln (Bombus impatiens) sollten drei Fragen beantwortet werden: (1) Zeigen Hummeln, die mit Sicherheit unerfahren im Sammeln auf Blüten sind, eine Präferenz für radiale Muster im Vergleich zu konzentrischen Mustern? (2) Erhöht ein vorheriges Training auf ein angeblich neutrales Muster die Präferenz für ein radiales Muster? (3) Und wenn ja, hat die Struktur des Trainingsmusters einen Effekt? Die Bienen wurden in einem radialen Labyrinth getestet, in dem ihnen 20 nicht belohnte Wahlmöglichkeiten zwischen radialen und konzentrischen Schwarz-Weiß-Mustern angeboten wurden. Die vorherigen Erfahrungen wurden durch folgendes Design festgelegt: keine vorherige Erfahrung mit belohnten Mustern im Labyrinth (Bienen, die zum ersten Mal das Nest verließen) im Vergleich zu vorherigen Erfahrungen mit belohnten Mustern im Labyrinth mit einem von vier Mustertypen (ein Ring von 8 Kreisen bzw. ein Raster von Kreisen, Quadraten oder Rauten, Abb. 2). Unter allen Bedingungen wurden die radialen Muster signifikant häufiger gewählt. Diese Präferenz war aber nur schwach ausgeprägt, wenn die Bienen keine vorherige Erfahrung hatten. Sie wurde dagegen deutlich vergrößert, wenn die Bienen zuvor Erfahrungen mit einem der drei Raster hatten: das Training mit diesen Mustern führt zu einer Überschätzung der nachfolgenden Präferenz für radiale Muster und umgekehrt zu einer Unterschätzung der Präferenz für konzentrische Muster. Die Wahl wurde nicht durch eine vorherige Erfahrung mit dem Ring von Kreisen beeinflusst, das heißt dass die vorherige belohnte Erfahrung weder die Aufmerksamkeit der Bienen verstärkt auf die Muster im Labyrinth lenkte noch deren Motivation erhöhte. Unsere Ergebnisse weisen auf einen Lernmechanismus bei Hummeln hin, bei dem die Ähnlichkeit zwischen Trainings- und Teststimuli abgeschätzt wird. Nehmen wir an, dass wir die spontane Wahl von tatsächlich unerfahrenen Hummeln beobachtet haben, dann ist Training im besten Fall unnötig. Im schlimmsten Fall kann es die Attraktivität der Blütencharakteristik verändern.

The effect of flower-like and non-flower-like visual properties on choice of unrewarding patterns by bumblebees

How do distinct visual stimuli help bumblebees discover flowers before they have experienced any reward outside of their nest? Two visual floral properties, type of a pattern (concentric vs radial) and its position on unrewarding artificial flowers (central vs peripheral on corolla), were manipulated in two experiments. Both visual properties showed significant effects on floral choice. When pitted against each other, pattern was more important than position. Experiment 1 shows a significant effect of concentric pattern position, and experiment 2 shows a significant preference towards radial patterns regardless of their position. These results show that the presence of markings at the center of a flower are not so important as the presence of markings that will direct bees there.

On the relationship between aggression and reproduction in pairs of orphaned worker bumblebees (Bombus impatiens)

This study characterized aggression and reproduction within pairs of orphaned bumblebee sisters (Bombus impatiens (Cresson, 1863)). Twenty-one pairs were filmed in the laboratory over 5–10xa0days. Frequencies of aggression and egg-laying were obtained for each bee, and the presence or absence of brood was manipulated. Aggression and egg-laying were more likely to co-occur in pairs placed without brood compared to pairs placed with brood. A significant positive correlation was found between members of a pair in the rates of aggression. In addition, a strong positive correlation was found in their rates of egg-laying: bees that had more sons also tended to have more nephews. The results show that under conditions of unrestricted food availability, behavioural interactions are compatible with continued reproduction by both orphaned workers. Though aggression may limit reproduction, it seems either to be an ineffective means of obtaining a reproductive monopoly in some situations and/or to be a set of behaviours invested with other possible functions.

Trapped: Assessing Attractiveness of Potential Food Sources to Bumblebees

Unrewarding artificial flowers that trapped approaching bumblebees were used here for the first time to assess the effects of several floral characteristics on floral attractiveness to bumblebees that never obtained food from flowers. Floral size and floral scent had no discernable effect. In a comparison between two colors (white and blue) and two shapes (radial and square), choice proportions for blue radial flowers were significantly greater than chance. Our proposed method is an alternative to prior training, with food associated either with visual or olfactory stimuli, which is unnecessary to obtain floral preferences by free-flying bumblebees exploring potential food sources.

How images may or may not represent flowers: picture–object correspondence in bumblebees (Bombus impatiens)?

Studies of bee cognition frequently use two-dimensional stimuli referred to as floral patterns, and yet how bees perceive pictorial representations is not known. An investigation of bumblebee (Bombus impatiens) picture–object correspondence was undertaken according to the theory of Fagot et al. (Picture perception in animals. Psychology Press Ltd, East Sussex, pp 295–320, 2000) that pictures and objects may be confused, perceived as independent or equivalent. In three experiments, bumblebees were given discrimination training and unrewarded testing in a radial maze. In the first experiment, preferences between artificial flowers and photographs of those flowers revealed a significant learned preference for the stimulus rewarded during training: no confusion following training. In the second experiment, bees did transfer learning from artificial flowers to photographs: some commonality between an object and photograph was perceived. In the third experiment, bees spontaneously generalized a learned preference for one artificial flower to its silhouette, but only for one of two flowers used in training. No generalization was obtained to drawn images. Some transfer between image and object is exhibited, likely by low-level feature matching, but transfer is poor with degraded images, cautioning against extrapolation of picture-based responding to natural correspondents. Despite evidence that bees exhibit some transfer while retaining discrimination, it is likely that the observed response is due to generalization more akin to confusion than true equivalence. Furthermore, although 2D patterning cues (line, edge and shade) provide discriminable cues for bees between 2D stimuli, it is not here supported that such features are perceived as equivalent to the intended floral structures.