Insect Navigation: How Do Wasps Get Home?

Production of adaptive movement patterns via an insect inspired spiking neural network central pattern generator

Navigation in ever-changing environments requires effective motor behaviors. Many insects have developed adaptive movement patterns which increase their success in achieving navigational goals. A conserved brain area in the insect brain, the Lateral Accessory Lobe, is involved in generating small scale search movements which increase the efficacy of sensory sampling. When the reliability of an essential navigational stimulus is low, searching movements are initiated whereas if the stimulus reliability is high, a targeted steering response is elicited. Thus, the network mediates an adaptive switching between motor patterns. We developed Spiking Neural Network models to explore how an insect inspired architecture could generate adaptive movements in relation to changing sensory inputs. The models are able to generate a variety of adaptive movement patterns, the majority of which are of the zig-zagging kind, as seen in a variety of insects. Furthermore, these networks are robust to noise. Because a large spread of network parameters lead to the correct movement dynamics, we conclude that the investigated network architecture is inherently well-suited to generating adaptive movement patterns.

Context-dependent use of olfactory cues by foragers of Vespula germanica social wasps

Food search is guided by cues from different sensory modalities, such as olfactory and visual. In social wasps, olfaction plays a key role in locating new resources. However, while several studies have focused on the importance of odours in predation, less is known about their role during scavenging, when spatial memories become a relevant guidance mechanism. Here, we investigated whether the use of odours during carrion exploitation by Vespula germanica wasps depends on whether they are locating or relocating the resource. By means of field choice experiments, we evaluated wasp response to odours: an odour eliciting a spontaneous aversive response, a learnt odour eliciting an appetitive response, and the conspecifics' odour eliciting an attractive response. Experiments were conducted in different contexts, i.e., during food localisation by naïve foragers, re-localisation of a resource at the learnt site and re-localisation of a resource that had been displaced from the learnt site. All olfactory stimuli evaluated markedly influenced foraging decisions in naïve wasps and in experienced wasps when the food was moved from the learnt location. However, odours were ignored during the wasp's return to the foraging site. These results suggest a cue hierarchy, in which local landmarks are more reliable to relocate carrion, while olfaction would be useful to locate novel resources or relocate a known source when spatial memories fail. Our findings demonstrate a context-dependent use of odours during carrion exploitation by V. germanica wasps and highlight the importance of spatial memories as an important factor modulating odour response.

What gaze direction can tell us about cognitive processes in invertebrates

Most visually guided animals shift their gaze using body movements, eye movements, or both to gather information selectively from their environments. Psychological studies of eye movements have advanced our understanding of perceptual and cognitive processes that mediate visual attention in humans and other vertebrates. However, much less is known about how these processes operate in other organisms, particularly invertebrates. We here make the case that studies of invertebrate cognition can benefit by adding precise measures of gaze direction. To accomplish this, we briefly review the human visual attention literature and outline four research themes and several experimental paradigms that could be extended to invertebrates. We briefly review selected studies where the measurement of gaze direction in invertebrates has provided new insights, and we suggest future areas of exploration.

Finding a place and leaving a mark in memory formation

Preference for spatial locations to maximize favorable outcomes and minimize aversive experiences helps animals survive and adapt to the changing environment. Both visual and non-visual cues play a critical role in spatial navigation and memory of a place supports and guides these strategies. Here we present the neural, genetic and behavioral processes involved in place memory formation using Drosophila melanogaster with a focus on non-visual cue based spatial memories. The work presented here highlights the work done by Dr. Troy Zars and his colleagues with an emphasis on role of biogenic amines in learning, cell biological mechanisms of neural systems and behavioral plasticity of place conditioning.

The role of spatial texture in visual control of bumblebee learning flights

When leaving the nest for the first time, bees and wasps perform elaborate learning flights, during which the location of the nest is memorised. These flights are characterised by a succession of arcs or loops of increasing radius centred around the nest, with an incremental increase in ground speed, which requires precise control of the flight manoeuvres by the insect. Here, we investigated the role of optic flow cues in the control of learning flights by manipulating spatial texture in the ventral and panoramic visual field. We measured height, lateral displacement relative to the nest and ground speed during learning flights in bumblebees when ventral and panoramic optic flow cues were present or minimised, or features of the ground texture varied in size. Our observations show that ventral optic flow cues were required for the smooth execution of learning flights. We also found that bumblebees adjusted their flight height in response to variations of the visual texture on the ground. However, the presence or absence of panoramic optic flow did not have a substantial effect on flight performance. Our findings suggest that bumblebees mainly rely on optic flow information from the ventral visual field to control their learning flights.