ABSTRACT Ants can navigate by comparing the currently perceived view with memorised views along a familiar foraging route. Models regarding route-following suggest that the views are stored and recalled independently of the sequence in which they occur. Hence, the ant only needs to evaluate the instantaneous familiarity of the current view to obtain a heading direction. This study investigates whether ant homing behaviour is influenced by alterations in the sequence of views experienced along a familiar route, using the frequency of stop-and-scan behaviour as an indicator of the ant's navigational uncertainty. Ants were trained to forage between their nest and a feeder which they exited through a short channel before proceeding along the homeward route. In tests, ants were collected before entering the nest and released again in the channel, which was placed either in its original location or halfway along the route. Ants exiting the familiar channel in the middle of the route would thus experience familiar views in a novel sequence. Results show that ants exiting the channel scan significantly more when they find themselves in the middle of the route, compared with when emerging at the expected location near the feeder. This behaviour suggests that previously encountered views influence the recognition of current views, even when these views are highly familiar, revealing a sequence component to route memory. How information about view sequences could be implemented in the insect brain, as well as potential alternative explanations to our results, are discussed.

SUMMARY Colours are quickly learnt by free-moving bees in operant conditioning settings. In the present study, we report a method using the classical conditioning of the proboscis extension response (PER) in restrained honeybees( Apis mellifera ), which allows bees to learn colours after just a few training trials. We further analysed how visual learning and discrimination is influenced by the quality of a stimulus by systematically varying the chromatic and achromatic properties of the stimuli. Using differential conditioning, we found that faster colour discrimination learning was correlated with reduced colour similarity between stimuli. In experiments with both absolute and differential conditioning, restrained bees showed poor colour discrimination and broad generalisation. This result is in strong contrast to the well-demonstrated ability of bees to finely discriminate colours under free-flight conditions and raises further questions about the temporal and perceptual processes underlying the ability of bees to discriminate and learn colours in different behavioural contexts.

SUMMARY With the exception of honeybees, there have been few good invertebrate models for associative learning. Grasshoppers and locusts (Orthoptera:Acrididae) possess a number of characteristics that make them excellent candidates for such studies, and in this paper we present a novel protocol,based on a Y-maze, that is specifically designed for studying their learning and choice behaviour. Three separate experiments were conducted using individual gregarious forms of the desert locust, Schistocerca gregaria . In our first experiment, coloured arms of a two-sided Y-maze provided a large or small amount of wheat for nine choice-trials. In the second experiment, locusts discriminated odours with wheat rewards for nine choice-trials. The odour-wheat reward combinations were then reversed for an additional nine choice-trials. For the third experiment, the locusts again discriminated odours, but here we used artificial foods and the rewards differed in their concentration of protein and digestible carbohydrate. The results indicate that, in addition to showing good acquisition of choice performance, the locusts also took less time to reach the larger-rewarded option. The data indicate that our protocol is highly sensitive for recording choice behaviour in acridids and reveals the potential they have for advancing our current understanding of associative learning and the field of learning in general.