Honeybee navigation: critically examining the role of the polarization compass

Although it is widely accepted that honeybees use the polarized-light pattern of the sky as a compass for navigation, there is little direct evidence that this information is actually sensed during flight. Here, we ask whether flying bees can obtain compass cues derived purely from polarized light, and communicate this information to their nest-mates through the ‘waggle dance’. Bees, from an observation hive with vertically oriented honeycombs, were trained to fly to a food source at the end of a tunnel, which provided overhead illumination that was polarized either parallel to the axis of the tunnel, or perpendicular to it. When the illumination was transversely polarized, bees danced in a predominantly vertical direction with waggles occurring equally frequently in the upward or the downward direction. They were thus using the polarized-light information to signal the two possible directions in which they could have flown in natural outdoor flight: either directly towards the sun, or directly away from it. When the illumination was axially polarized, the bees danced in a predominantly horizontal direction with waggles directed either to the left or the right, indicating that they could have flown in an azimuthal direction that was 90° to the right or to the left of the sun, respectively. When the first half of the tunnel provided axial illumination and the second half transverse illumination, bees danced along all of the four principal diagonal directions, which represent four equally likely locations of the food source based on the polarized-light information that they had acquired during their journey. We conclude that flying bees are capable of obtaining and signalling compass information that is derived purely from polarized light. Furthermore, they deal with the directional ambiguity that is inherent in polarized light by signalling all of the possible locations of the food source in their dances, thus maximizing the chances of recruitment to it.     

Neural mechanisms in insect navigation: polarization compass and odometer

Insect navigation relies on path integration, a procedure by which information about compass bearings pursued and distances travelled are combined to calculate position. Three neural levels of the polarization compass, which uses the polarization of skylight as a reference, have been analyzed in orthopteran insects. A group of dorsally directed, highly specialized ommatidia serve as polarization sensors. Polarization-opponent neurons in the optic lobe condition the polarization signal by removing unreliable and irrelevant components of the celestial stimulus. Neurons found in the central complex of the brain possibly represent elements of the compass output. The odometer for measuring travelling distances in honeybees relies on optic flow experienced during flight, whereas desert ants most probably use proprioreceptive cues.     

Spectral information as an orientation cue in dung beetles

During the day, a non-uniform distribution of long and short wavelength light generates a colour gradient across the sky. This gradient could be used as a compass cue, particularly by animals such as dung beetles that rely primarily on celestial cues for orientation. Here, we tested if dung beetles can use spectral cues for orientation by presenting them with monochromatic (green and UV) light spots in an indoor arena. Beetles kept their original bearing when presented with a single light cue, green or UV, or when presented with both light cues set 180° apart. When either the UV or the green light was turned off after the beetles had set their bearing in the presence of both cues, they were still able to maintain their original bearing to the remaining light. However, if the beetles were presented with two identical green light spots set 180° apart, their ability to maintain their original bearing was impaired. In summary, our data show that ball-rolling beetles could potentially use the celestial chromatic gradient as a reference for orientation.     

Evidence for instantaneous e-vector detection in the honeybee using an associative learning paradigm

Many insects use the polarization pattern of the sky for obtaining compass information during orientation or navigation. E-vector information is collected by a specialized area in the dorsal-most part of the compound eye, the dorsal rim area (DRA). We tested honeybees' capability of learning certain e-vector orientations by using a classical conditioning paradigm with the proboscis extension reflex. When one e-vector orientation (CS+) was associated with sugar water, while another orientation (CS-) was not rewarded, the honeybees could discriminate CS+ from CS-. Bees whose DRA was inactivated by painting did not learn CS+. When ultraviolet (UV) polarized light (350 nm) was used for CS, the bees discriminated CS+ from CS-, but no discrimination was observed in blue (442 nm) or green light (546 nm). Our data indicate that honeybees can learn and discriminate between different e-vector orientations, sensed by the UV receptors of the DRA, suggesting that bees can determine their flight direction from polarized UV skylight during foraging. Fixing the bees' heads during the experiments did not prevent learning, indicating that they use an 'instantaneous' algorithm of e-vector detection; that is, the bees do not need to actively scan the sky with their DRAs ('sequential' method) to determine e-vector orientation.     

Interneurones of the central complex in the bee brain (Apis mellifera,L.)

The response characteristics of 46 interneurones of the central complex in the bee brain to visual, various antennal and mechanical stimuli were studied. Different types of neurones can be distinguished anatomically. Intrinsic cells arborize only in the central complex. Segmental neurones innervate a segment of the protocerebral bridge and the central body and project to the lateral accessory lobes. Fan-shaped neurones have arborizations throughout the whole upper or lower division of the central body.Intrinsic neurones of the protocerebral bridge process visual information, the other cells display different and often multimodal response characteristics, which cannot be correlated with the neuroanatomical groups. Seventeen per cent of the cells did not respond at all to the stimuli presented. The role of the central complex in the processing of sensory information is discussed and compared with the mushroom bodies and the diffuse protocerebral lobes.     

夜行性昆虫微光视觉行为及其视觉适应机制

作为昆虫种群的重要组成部分,夜行性昆虫成功进化出了与其生存环境相适应的感觉机制,普遍认为夜行性昆虫主要依靠嗅觉和机械性感受等来探索环境,其视觉器官发生了退化或功能丧失.近年来,随着红外夜视、视网膜电位(electroretinogram,ERG)和视觉神经等生物新技术的应用,昆虫视觉生态学研究出现了突破性进展,自200...     

浙中地区林木蚧虫目录

本文系统整理了分布于浙江中部地区的林木蚧虫目录,共有8科41属64种。     

Behavioural evidence for polarization vision in crickets

ABSTRACT. Tethered field crickets, Gryllus campestris L., walking on an air-suspended bail exhibit a spontaneous response to the e-vector of polarized light presented from above: E-vector orientation controls strength and direction of turning tendency. Experiments in which different eye regions are covered with paint suggest that this response is mediated by the anatomically and physiologically specialized dorsal rim area of the compound eye. We conclude that crickets have polarization vision and that the dorsal rim area of the eye plays a key role in this sensory capacity.     

Anatomical and physiological characteristics of individual neurones in the central antennal pathway of insects

Signals of tens up to hundreds of thousands of (mostly olfactory) receptor cells on an insect antenna are switched to a comparatively low number of neurones in the antennal lobe of the deutocerebrum in circumscribed units of neuropile, the glomeruli. Each glomerulus is connected via its output neurone to two separate neuropiles (calyces of mushroom body, and lateral lobe) of the protocerebrum. Local interneurones interconnect between the glomeruli. Certain modes of convergence between receptors and central neurones provide for a very high sensitivity of the latter to certain odours and their sensitivity for complex odour stimuli, and in many cases for a marked multimodality. Anatomical and physiological data are given especially for pheromone sensitive neurones and their projections.     

The role of the sun in the celestial compass of dung beetles

Recent research has focused on the different types of compass cues available to ball-rolling beetles for orientation, but little is known about the relative precision of each of these cues and how they interact. In this study, we find that the absolute orientation error of the celestial compass of the day-active dung beetle Scarabaeus lamarcki doubles from 16° at solar elevations below 60° to an error of 29° at solar elevations above 75°. As ball-rolling dung beetles rely solely on celestial compass cues for their orientation, these insects experience a large decrease in orientation precision towards the middle of the day. We also find that in the compass system of dung beetles, the solar cues and the skylight cues are used together and share the control of orientation behaviour. Finally, we demonstrate that the relative influence of the azimuthal position of the sun for straight-line orientation decreases as the sun draws closer to the horizon. In conclusion, ball-rolling dung beetles possess a dynamic celestial compass system in which the orientation precision and the relative influence of the solar compass cues change over the course of the day.     

Flight-induced compass representation in the monarch butterfly heading network

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The molecular basis of mechanisms underlying polarization vision

The underlying mechanisms of polarization sensitivity (PS) have long remained elusive. For rhabdomeric photoreceptors, questions remain over the high levels of PS measured experimentally. In ciliary photoreceptors, and specifically cones, little direct evidence supports any type of mechanism. In order to promote a greater interest in these fundamental aspects of polarization vision, we examined a varied collection of studies linking membrane biochemistry, protein-protein interactions, molecular ordering and membrane phase behaviour. While initially these studies may seem unrelated to polarization vision, a common narrative emerges. A surprising amount of evidence exists demonstrating the importance of protein-protein interactions in both rhabdomeric and ciliary photoreceptors, indicating the possible long-range ordering of the opsin protein for increased PS. Moreover, we extend this direction by considering how such protein paracrystalline organization arises in all cell types from controlled membrane phase behaviour and propose a universal pathway for PS to occur in both rhabdomeric and cone photoreceptors.     

Resolving the heading‐direction ambiguity in vertical‐beam radar observations of migrating insects

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Evidence for the possible existence of a second polarization-vision pathway in the locust brain

For spatial orientation and navigation, many insects derive compass information from the polarization pattern of the blue sky. The desert locust Schistocerca gregaria detects polarized light with a specialized dorsal rim area of its compound eye. In the locust brain, polarized-light signals are passed through the anterior optic tract and tubercle to the central complex which most likely serves as an internal sky compass. Here, we suggest that neurons of a second visual pathway, via the accessory medulla and posterior optic tubercle, also provide polarization information to the central complex. Intracellular recordings show that two types of neuron in this posterior pathway are sensitive to polarized light. One cell type connects the dorsal rim area of the medulla with the medulla and accessory medulla, and a second type connects the bilaterally paired posterior optic tubercles. Given the evidence for a role of the accessory medulla as the master clock controlling circadian changes in behavioral activity in flies and cockroaches, our data open the possibility that time-compensated polarized-light signals may reach the central complex via this pathway for time-compensated sky-compass navigation.     

昆虫对偏振光的响应及感受机理研究进展

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