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- Publisher
- The Company of Biologists
- Copyright
- © 2021 The Company of Biologists. All rights reserved.
- ISSN
- 0022-0949
- eISSN
- 0022-0949
- DOI
- 10.1242/jeb.228254
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- See Article on Publisher Site
Abstract
© 2020. Published by The Company of Biologists Ltd | Journal of Experimental Biology (2020) 223, jeb228254. doi:10.1242/jeb.228254 RESEARCH ARTICLE 1 1,2 1, Norihiro Kobayashi , Ryuichi Okada and Midori Sakura * ABSTRACT Labhart, 1988; Heinze and Homberg, 2007, 2009; Sakura et al., 2008; Heinze and Reppert, 2011; Bech et al., 2014) mechanisms. Many insects exploit the partial plane polarization of skylight for visual The e-vector detection in insects is mediated by a group of compass orientation and/or navigation. In the present study, using a specialized ommatidia located in the most dorsal part of the tethering system, we investigated how flying bees respond to polarized compound eye, the dorsal rim area (DRA), in which the light stimuli. The behavioral responses of honeybees (Apis mellifera)to photoreceptors are monochromatic and highly polarization a zenithal polarized light stimulus were observed using a tethered sensitive (for review see Labhart and Meyer, 1999; Wehner and animal in a flight simulator. Flight direction of the bee was recorded by Labhart, 2006). The neural pathway of polarization vision in the monitoring the horizontal movement of its abdomen, which was brain has been documented in several species. The photoreceptors in strongly anti-correlated with its torque. When the e-vector orientation of the DRA terminate in the lamina or the medulla in the optic lobe, the polarized light was rotated clockwise or counterclockwise, the and, from there, polarized light signals primarily project into the bee responded with periodic right-and-left abdominal movements; central complex through a pathway involving the lower unit of the however, the bee did not show any clear periodic movement under the anterior optic tubercle and lower division of the central body static e-vector or depolarized stimulus. The steering frequency of (Homberg, 2008). The central complex, one of the higher centers of the bee was well coordinated with the e-vector rotation frequency of the the insect brain, is considered to be the location of an internal stimulus, indicating that the flying bee oriented itself to a certain compass (for review see Homberg et al., 2011; Heinze, 2017), e-vector orientation, i.e. exhibited polarotaxis. The percentage of bees although it is still unclear how the central complex controls the exhibiting clear polarotaxis was much smaller under the fast stimulus −1 animal’s steering during navigation. (3.6 deg s ) compared with that under a slow stimulus (0.9 or −1 Foraging behavior in social insects, such as ants and bees, is a 1.8 deg s ). Bees did not demonstrate any polarotactic behavior useful model system for studying insect navigation because they after the dorsal rim area of the eyes, which mediates insect polarization repeatedly go back and forth between the nest and a feeding site. vision in general, was bilaterally covered with black paint. Preferred In particular, the path integration mechanisms in desert ants e-vector orientations under the clockwise stimulus varied among (Cataglyphis) have been extensively studied in regard to insect individuals and distributed throughout −90 to 90 deg. Some bees navigation (Wehner, 2003; Collett and Cardé, 2014), and showed similar preferred e-vector orientations for clockwise and Cataglyphis are well known to choose their heading direction counterclockwise stimuli whereas others did not. Our results strongly using celestial polarization cues during long-distance navigation suggest that flying honeybees utilize the e-vector information from the (Fent, 1986; Wehner, 1997; Wehner and Müller, 2006). In addition skylight to deduce their heading orientation for navigation. to path integration based on the polarization compass, ants can learn KEY WORDS: Insect flight, Polarization vision, Dorsal rim area, visual landmarks or panoramic views at familiar locations and use Polarotaxis, Navigation them for local navigation (Collett et al., 1992; Wehner et al., 1996; Collett et al., 1998; Graham and Cheng, 2009; Narendra et al., INTRODUCTION 2013). Honeybees also undertake long-distance foraging trips that As a result of sunlight scattering in the atmosphere, the skylight is may reach over 5 km (Couvillon et al., 2014). Usage of skylight partially plane polarized and the celestial e-vectors are arranged in a polarization in honeybees to detect their intended travel direction concentric pattern around the sun (Strutt, 1871; Wehner, 1997). It is was first described by von Frisch (1967) through a series of well known that many insects exploit this skylight polarization for sophisticated behavioral studies on the waggle dance. Thereafter, visual compass orientation and/or navigation (for review see the waggle dance orientations of the nest-returning bees from a Wehner, 1994; Wehner and Labhart, 2006; Heinze, 2014). There certain feeder have been intensively studied. These studies were have been an enormous number of studies about insect polarization conducted under a patch of polarized light stimulus or part of the vision, not only at the behavioral level (e.g. Dacke et al., 2003; sky, and an internal representation of the celestial e-vector map has Reppert et al., 2004; Henze and Labhart, 2007; Weir and Dickinson, been proposed (Rossel and Wehner, 1982, 1986, 1987; Wehner, 2012), but also at the neural network level, such as sensory (e.g. 1997). These systematic studies have focused on modification of the Blum and Labhart, 2000; Weir et al., 2016) and central brain (e.g. waggle dance orientation and not on how the bees perceive polarized light from the sky en route to/from the nest. More recently, polarized light detection in flying bees has been demonstrated using Department of Biology, Graduate School of Science, Kobe University, Rokkodai a four-armed tunnel maze with a polarizer on top (Kraft et al., 2011), 1-1, Nada-ku, Kobe, Hyogo 657-8501, Japan. School of Human Science and Environment, University of Hyogo, 1-1-12 Shinzaike-Honcho, Himeji, Hyogo 670- and it was revealed that bees choose the arms based on their 0092, Japan. previous e-vector experiences. Moreover, it has also been *Author for correspondence ([email protected]) demonstrated that bees memorize the e-vector orientations experienced during their foraging flight and use that memory for N.K., 0000-0002-2046-4457; R.O., 0000-0001-8645-5759; M.S., 0000-0002- subsequent waggle dances (Evangelista et al., 2014). In these 0857-7176 studies, the tunnel was made as the bee could receive parallel or vertical e-vector stimulus with respect to their moving direction. Received 4 May 2020; Accepted 16 October 2020 Journal of Experimental Biology RESEARCH ARTICLE Journal of Experimental Biology (2020) 223, jeb228254. doi:10.1242/jeb.228254 Indeed, by classical conditioning experiments, it has been shown Black box that the honeybees are able to discriminate polarized light of 0 deg e-vector orientation with that of 90 deg (Sakura et al., 2012). Behavioral responses of moving insects to the overhead polarized light stimulus have been intensively studied using a tethered animal. Orientation to the polarized light, i.e. polarotaxis (Mathejczyk and Wernet, 2019), has been demonstrated in tethered walking insects Light (cricket, Gryllus campestris; Brunner and Labhart, 1987; fly, Musca Depolarizer domestica; von Philipsborn and Labhart, 1990) and also in tethered flying insects. In the locust (Schistocerca gregaria), direct monitoring Holographic diffuser of yaw-torque responses showed clear polarotactic right-and-left turns Polarizer to rotating polarized light (Mappes and Homberg, 2004). In tethered monarch butterflies (Danaus plexippus), measuring flight orientations USB Tethered using an optical encoder revealed that their flight orientation under camera bee natural skylight was clearly affected by a dorsally presented Circulator polarization filter (Reppert et al., 2004; Stalleicken et al., 2005). Similar orientation to polarized skylight has also been demonstrated in PC monitor Drosophila (Weir and Dickinson, 2012; Mathejczyk and Wernet, 2019), in which a fly was magneticallytetheredinthe arenaand its Fig. 1. Experimental setup for monitoring Apis mellifera flight under polarized light stimuli. Light from a xenon lamp was equally depolarized and flight heading was recorded from above by an infrared camera. then linearly polarized using a UV-transmitted polarizer. A bee was tethered Recently, some behavioral studies have succeeded to make a dorsally under the polarizer and its flight was monitored by a USB camera. For the tethered bee stably fly by presenting lateral optic flow and frontal air- stable flight of a tethered bee, rectified wind from a circulator and moving black- flow stimuli (Luu et al., 2011; Taylor et al., 2013). It was observed that and-white stripes on a PC monitor were presented. the tethered bees showed ‘streamlining’ responses, whereby they raised their abdomen in a correlated manner with the speed of the optic and air-flow stimuli. In the present study, we investigated how flying connected to a tunnel that carried the wind stimulus into the box. The bees respond to polarized light stimuli using a tethering system. We end of the tunnel (diameter, 8 cm), consisting of many fine plastic constructed a flight simulator, in which we could examine a tethered straws to reduce the turbulent flow of wind, was fixed at 10 cm from bee’s flight response to a rotating polarized stimulus, and found that the bee’s head. The wind speed at the bee’s head was almost constant, −1 −1 they tended to orient themselves to a certain e-vector direction, i.e. they ranging between 1.7 m s and 2.0 m s .The LCDmonitor exhibited clear polarotaxis, during the flight. (RDT1711LM; Mitsubishi Electric, Tokyo, Japan; 75 Hz refresh rate), covered with a sheet of tracing paper to eliminate any polarized MATERIALS AND METHODS components of the light, was located 5 cm beneath the tethered bee. Animals The front-to-back optic flow stimulus of moving black-and-white The honeybees, Apis mellifera ligustica Spinola 1806, used in this stripes (Michelson contrast, 0.25) was displayed on the monitor using ++ study were reared in normal ten-frame hives on the campus of Kobe a self-made program in Microsoft Visual C . The size of the area on University, Hyogo, Japan. Forager honeybees with pollen loads the monitor displaying the stripes was 159×163 deg, and the width of were collected at the hive entrance before the experiment and a single stripe was 40 deg, measured from the bee’shead position. −1 anesthetized on ice or in a refrigerator. An L-shaped metal rod for The speed of the stimulus was ∼900 deg s ,asseen by the bee, tethering was attached to the pronotum of an anesthetized bee, as which is fast enough to elicit the highest streamlining responses from previously described (Luu et al., 2011). Briefly, the hair on the a bee (Luu et al., 2011). pronotum was gently shaved using a small piece of a razor blade, Light from a xenon lamp (LC8, L8253; Hamamatsu Photonics, and the metal rod was adhered using a small amount of light-curing Hamamatsu, Japan) was applied above the bee using a quartz light adhesive (Loctite; Henkel, Dusseldorf, Germany). Image analyses guide. The light was filtered using a depolarizer (DPU-25; ThorLabs, of bee behavior (see below) were conducted by marking the tip of Newton, NJ, USA) at the end of the light guide to eliminate any the abdomen with a white, light-curing dental sealant (Conseal f; polarized components of the light, and a holographic diffuser SDI Limited, Bayswater, Australia). Next, the bees were placed in a (48-522; Edmund Optics, Barrington, NJ, USA) was clamped under warm room to recover from anesthesia and fed several drops of 30% the end of the light guide. The diffuser reduced illuminance sucrose solution before the experiment. irregularity and increased the size of the light fit around a linear We did not purposely remove pollen loads of the bees but some of polarizer (HN42HE; diameter, 15 cm; Polaroid Company, them lost the pollen loads during the preparation processes. Cambridge, MA, USA) beneath the diffuser. The polarizer was Therefore, bees with and without pollen loads were evaluated mounted on a circular holder that could be rotated using a DC motor. during the experiment. The stimulus was centered at the bee’s zenith (with respect to flying head position) at a distance of 15 cm, providing a dorsal, polarized Setup stimulus of 53 deg in diameter. In the experiments in which The experiments were performed using a custom-made black box unpolarized light stimulus was used, the depolarizer was clamped (Fig. 1) in a dark room. A tethered bee was mounted in the box by just above the bee’s head instead of at the end of the light guide, such attaching the end of the metal rod to a three-dimensional manipulator, that the size of the light stimulus covered the entire receptive field of such that the bee’s location could be adjusted manually. The flying the bee’s DRA. Under this condition, we could assess the effect of a behavior of the tethered bee was enhanced by stimulating the bee with slight fluctuation in light intensity caused by the polarizer rotation a headwind from an air circulator and front-to-back optic flow from with the same spectrum of light (300–620 nm). The intensity of the an LCD monitor. The circulator was located outside the box and polarized and unpolarized light at the animal level was ∼1000 lx. Journal of Experimental Biology RESEARCH ARTICLE Journal of Experimental Biology (2020) 223, jeb228254. doi:10.1242/jeb.228254 Behavioral experiments The flying behavior of the tethered bee was monitored using a USB The behavioral experiments were performed between 11:00 h and camera (IUC-300CK2; Trinity, Gunma, Japan) placed behind the bee 18:00 h local time. A bee was fixed in the experimental box with the (see Fig. 1). Images of the bee were recorded at a rate of 1 Hz, i.e. 600 metal rod attached for tethering after complete recovery from images for 10 min data. For each image, the x-coordinate of the bee’s anesthesia. First, we let the bee hold a small piece of paper so that it abdominal tip was determined manually to estimate flying orientation could not start flying. The e-vector angle of the polarizer was set at (Fig. S1). A series of x-coordinates was then calibrated into actual 0 deg with respect to the bee’s body axis, and static black-and-white distances (in mm) from the center, where the tethering wire was fixed stripes were displayed on the PC monitor. After the bee had been and used for further analysis (see below). familiarized with the box, the paper was removed to allow the bee Whether the DRA of the compound eye was involved in flying to start flying, and the wind and optic flow stimuli were simultaneously behavior under the polarized light stimulus was determined using presented. After the bee’s flight became stable, during which the bee bees in which the DRAs had been painted (see Fig. 7C,D). The DRAs raised its abdomen, did not thrash its legs and extended its antennal were painted as in our previous work (Sakura et al., 2012), with black flagella forward, the polarizer started rotating slowly (0.9, 1.8 or acrylic emulsion paint (Herbol, Cologne, Germany) under a −1 3.6 deg s ), and the behavior of the bee was monitored for 600 s. dissecting microscope just before the tethering procedure described When a bee stopped flying before 600 s, the data were not used in the above. The DRA of a compound eye is visually identifiable because analysis. In the experiments shown in Figs 2 and 3, the bee was tested the cornea appears slightly gray and cloudy (Meyer and Labhart, three times under different stimulus conditions: clockwise (CW), static 1981). Because it was technically not possible to cover the DRA and counterclockwise (CCW). To eliminate possible effects of the alone, which consists of only four to five horizontal rows of stimulus sequence, the order of these three stimuli was randomly ommatidia (Meyer and Labhart, 1981; Wehner and Strasser, 1985), a changed for each experiment. In other cases, a bee was tested only with small area of the unspecialized dorsal region next to the DRA was the CW stimulus. also painted. After the experiments, the paint cover was checked in all A B −1 −1 (a) CW (1.8 deg s ) (a) CW (1.8 deg s ) 1 5 –1 360 deg 0.01 0.02 0.03 0.04 0 deg 200 s (b) Static (b) Static –1 0.01 0.02 0.03 0.04 0 deg −1 −1 (c) CCW (1.8 deg s ) (c) CCW (1.8 deg s ) –1 360 deg 0.01 0.02 0.03 0.04 0 deg Frequency (Hz) Fig. 2. Abdominal movements of Apis mellifera under a polarized light stimulus. (A,B) Trajectories of the abdominal tip (A) and power spectra (PSs; B) under −1 −1 clockwise (CW; 1.8 deg s ; a), static (b) and counterclockwise (CCW; 1.8 deg s ; c) stimuli. The lower trace in each trajectory (Pol.) indicates the e-vector orientation of the polarizer with respect to the bee’s body axis, and preferred e-vector orientations of the bee are indicated by dashed line arrows (126 deg and 112 deg for CW and CCW stimulus, respectively). Under a rotating e-vector (a,c), the abdomen showed periodic movements from side to side. Dashed lines indicate the peaks at the stimulus rotation frequency (0.01 Hz). The first 200 s of the trajectory (gray) was not used for FFT analysis. Movement (mm) Pol. –1 Relative power (10 ) Journal of Experimental Biology RESEARCH ARTICLE Journal of Experimental Biology (2020) 223, jeb228254. doi:10.1242/jeb.228254 AB C −1 −1 Static CW (1.8 deg s ) CCW (1.8 deg s ) 2 2 12 2 12 12 (N=21) (N=21) (N=21) 1 6 1 6 1 6 0 0 0 0 0 0.01 0.02 0.03 0.04 0.01 0.02 0.03 0.04 0.01 0.02 0.03 0.04 DE F 1 1 0.8 5 5 0.6 10 10 10 0.4 15 15 15 0.2 20 20 0.01 0.02 0.03 0.04 0.01 0.02 0.03 0.04 0.01 0.02 0.03 0.04 Frequency (Hz) Fig. 3. PSs of the abdominal movements of Apis mellifera under a polarized light stimulus. (A–C) Averaged PSs (black lines) and histograms of the maximum peak in each PS (gray bars) are shown (N=21). Dashed lines indicate the peaks at the stimulus rotation frequency (0.01 Hz). (D–F) Heat maps of PSs −1 (normalized by the maximum power) of all experimental bees shown in A–C(N=21). A,D, CW stimulus (1.8 deg s ); B,E, static stimulus; C,F, CCW stimulus −1 (1.8 deg s ). the experimental animals under a dissecting microscope. Data for where a and b are Fourier cosine and sine coefficient for 0.01 Hz, n n cases in which any of the paint was missing were excluded from respectively. further analysis. The three ocelli, which are not involved in The PEO for a CW or CCW stimulus was given as follows: polarization vision (Rossel and Wehner, 1984), were not painted in w þ 90 the experiments. PEO ¼ 90 ; ð2Þ cw w þ 90 Analysis and statistics PEO ¼ 180 ; ð3Þ ccw All data analyses were performed using self-made programs in MATLAB (MathWorks, Natick, MA, USA). Periodicity of the time where PEO , and PEO indicate the PEO for a CW and CCW cw ccw course of the abdominal tip location was analyzed using fast Fourier stimulus, respectively (in deg). The uniformity of the distribution of transform (FFT). For FFT, data for only the last 400 s of each PEOs was statistically analyzed by the Rayleigh test (Batschelet, trajectory (600 s in total) were used because the periodicity of a bee’s 1981) using Oriana software (ver. 3.12; Kovach Computing Services, flight was occasionally obscure at the beginning of the stimulus (e.g. Isle of Anglesey, UK), in which the axial PEO data were converted to see gray areas in Fig. 2Ac). The relative power spectrum (PS) was angular data by multiplying by 2. calculated, and peak frequencies were determined. In cases in which the PS had multiple peaks, we took into account only the maximum Simultaneous recordings of abdominal images and yaw and second-maximum peaks for analysis. We defined a bee to be torque aligned with a certain e-vector orientation, or showing ‘polarotaxis’, To determine the relationship between a tethered bee’s abdominal when the PS of the bee showed the maximum or the second-maximum location and its flying behavior (Fig. S1), we simultaneously peak at the stimulus frequency, half rotation of the polarizer (note recorded abdominal images and the yaw torque of a flying tethered that the e-vectors 0 deg and 180 deg are identical); i.e. 0.5, 0.01 and bee in the following procedures. Forager bees were collected at the −1 0.02 Hz for 0.9, 1.8 and 3.6 deg s stimuli, respectively. hive entrance in the morning (09:00–10:00 h) and anesthetized in a Distributions of bees showing polarotaxis were statistically analyzed refrigerator at 4°C for 10–20 min. A small, thin metal plate using Fisher’s exact test or Cochrane’s Q-test with post hoc McNemar (1×2 mm, 0.02 mm thickness) was glued on the center of the thorax test for among- or within-group comparisons, respectively. In of each bee with beeswax. After recovery from anesthesia, the bee addition, the largest peak in the PS of each bee was determined to was tethered by attaching the metal plate to a torque meter (SH-02S; compare the distribution of the peaks by a bee. Suzuko, Yokohama, Japan). Before starting the experiment, a small −1 In experiments in which a 1.8 deg s CW stimulus was used, a piece of paper was provided to cause the bee to remain stationary preferred e-vector orientation (PEO) for each bee that demonstrated and familiarize itself with the experimental environment. polarotaxis was examined. The PEO was obtained from a phase (w; All experiments were performed under dark conditions. Two in deg) of the stimulus frequency component (0.01 Hz) in the monitors were facing each other and a bee was positioned at the division signal after FFT. Here, center of the monitors and 13 cm from each monitor. Vertical black- white gratings (visual angle, 125 deg) with a sinusoidal illuminance change were presented on both monitors and moved from front to w ¼ tan ; ð1Þ n rear of the bee. To facilitate flight, a gentle laminar air flow Bee ID –1 Relative power (10 ) Number of bees Journal of Experimental Biology RESEARCH ARTICLE Journal of Experimental Biology (2020) 223, jeb228254. doi:10.1242/jeb.228254 −1 (∼1.8 m s ) was provided by a fan placed in front of the bee. Simultaneous recordings of the abdominal images and the yaw torque During the flight, the bee was monitored by a charge-coupled device of a flying tethered bee showed a strong negative correlation, i.e. the camera (Sun Star 300, Electrophysics, Fairfield, NJ, USA) located bee’s abdominal tip moved right when the bee turned left and vice to the posterior of the bee facing the abdominal tip. By using this versa. Therefore, the bee’s periodic abdominal movement under the camera, we were able to determine the position of the tip of the rotating e-vector stimulus could be explained by the bee periodically abdomen, as well as observe the behavior of the bee. changing its steering action to adjust the flying direction to a certain Three kinds of visual stimuli with air flow were applied for 30 s to e-vector orientation. If a given e-vector heading was desirable, the bee induce a putative ‘straight’ or ‘turning’ flight. For straight flight, treated it as a target, steering left as the target approached in CW −1 gratings of both monitors moved at the same speed of 110.5 deg s rotation and then steering right as it exited. At the orthogonal e-vector (a spatial frequency is 7.5 Hz). For putative turning flight, either the heading (an anti-target), the bee first steered right on CW approach −1 left or right monitor presented a faster speed (331.5 deg s ), by and left on exit. Such a steering pattern could produce abdomen −1 moving one at a greater speed than the other (110.5 deg s ) and movement at twice the frequency of stimulus rotation given the vice versa. In this condition, the stimulated bee, in general, tended to axially symmetric e-vector stimulus. The PEO and PEO of the cw ccw turn to the slower side. One bee was subjected to three kinds of bee shown in Fig. 2, calculated by the phase of the 0.01 Hz visual stimuli three times each. Air flow was constant throughout the component in the PS (see Materials and Methods), were 126 deg and experiments. Only bees that exhibited 30 s flight were used for 112 deg, respectively (Fig. 2, dashed arrows). Around these e-vector further analysis. directions, the bee’s abdominal tip was located at almost the center, The yaw torque from the torque meter was stored in the PC through indicating that the bee did not change its flying direction. an A/D converter using custom-made software, with a sampling rate Fig. 3D–F summarizes the PSs of all experimental bees tested –1 of 120 points s . A video movie was simultaneously stored with 30 under the three different conditions; CW, static and CCW polarized –1 frames s in the avi format. To see the correlation between yaw light stimulus. Under the CW and CCW rotations, the PS often had a torque and flight posture, the tip of the abdomen was manually strong power at 0.0025 Hz and/or 0.01 Hz regardless of the tracked frame by frame after converting the movie into JPG images rotational direction (Fig. 3D,F), whereas it had a strong power with an interval of 0.1 s. By using custom-made software, we only at 0.0025 Hz with static stimulus in most bees (Fig. 3E). A obtained x-and y-coordinates along with time. Because we were only significantly higher number of bees (four, three and two of 21 bees interested in horizontal movements of the abdomen, we used only the for both CW and CCW, CW only and CCW only, respectively) x-coordinates for further analysis. displayed the maximum peaks at 0.01 Hz in the PS compared with We calculated correlation coefficients between torque and the that (none of the 21 bees) under the static 0 deg e-vector stimulus abdominal movement for all flights of all individuals. For (Fig. 3A–C; CW, P=0.008; CCW, P=0.014; Cochrane’s Q-test with calculation, we normalized horizontal movements individually as post hoc McNemar test). In the averaged PS, a clear peak was noted follows. All sampled x-coordinates obtained from three putative at 0.01 Hz under the CW or CCW stimulus, although another strong straight flights of a bee were averaged as a neutral position for the power was detected at 0.0025 Hz (Fig. 3A,C), and strong power was bee. Then, relative positions of the abdominal tips to the neutral only detected at 0.0025 Hz under the static stimulus (Fig. 3B). To position were calculated for each flight by converting pixels to confirm that the strong power at 0.0025 Hz reflects the entire data distance (in mm). In this normalization, a positive value indicated length, we also performed FFT analysis for the data under CW that the abdomen was positioned on the right side to the base stimulus of different data lengths, i.e. 100, 200, 300, 400, 500 and position and a negative value indicated the left. For yaw torque, a 600 s (Fig. S2). In all cases, the averaged PS curves have two peaks, −1 positive/negative value meant a CW/CCW turn. Only yaw torques one at (data length) Hz and the other at 0.01 Hz. The peak at of the corresponding time points to the manual tracking were used, 0.01 Hz was always found in the PS regardless of the data length i.e. the sampling interval was reduced to 0.1 s. Because the posture (Fig. S2, red bars), indicating that the trajectory has certain of a flying bee was not stable for the first 2–5 s after the onset of the periodicity with 0.01 Hz. Considering that the strong power at stimulation, we discarded the first 10 s of data and used only the last 0.0025 Hz based on the data length was often found in the PSs, we 20 s for the correlation analysis. next counted the number of the bees showing the maximum or the second-maximum peak at 0.01 Hz in each stimulus condition. In RESULTS total, over half of the experimental bees showed a clear peak at Polarotactic behavior of tethered bees 0.01 Hz in the PS under the rotating e-vector stimulus (Fig. 3D,F; Under our experimental conditions, approximately two-thirds of the ten, two and four of 21 bees for both CW and CCW, CW only and experimental tethered bees could stably fly for over 10 min. A CCW only, respectively); however, under the static 0 deg e-vector representative horizontal trajectory of a bee’s abdominal tip under the stimulus, only two of the 21 bees showed a 0.01 Hz peak in the PS, three different polarized light conditions is shown in Fig. 2A. When which was significantly smaller than the number of bees showing a the e-vector of the polarized light stimulus was gradually peak at 0.01 Hz under the rotating stimulus (Fig. 3E; CW, P=0.008; −1 (1.8 deg s ) rotated CW or CCW, the bee showed periodic right- CCW, P=0.001; Cochrane’s Q-test with post hoc McNemar test). and-left abdominal movement, regardless of the rotational direction To determine whether the periodic movements were not elicited by (Fig. 2Aa,c). The FFT analysis of the last 400 s of the trajectory data the rotation of the e-vector, but rather by a slight fluctuation in light clearly showed that these abdominal movements were synchronized intensity caused by the polarizer rotation, we projected an unpolarized with an e-vector rotating frequency of 0.01 Hz (180 deg rotation) light stimulus through the depolarizer beneath the CW rotating (Fig. 2Ba,c). Conversely, a bee did not show such periodic movement polarizer (see Materials and Methods). Under the unpolarized light under the static e-vector stimulus (0 deg with respect to the body axis; stimulus, the bees did not show any clear movements coincident with Fig. 2Ab), and the peak of the PS was detected at 0.0025 Hz, which is the polarizer rotation (Fig. 4A). Furthermore, no detectable peak at coincident with the entire data length (400 s), instead of at 0.01 Hz 0.01 Hz was noted in the averaged PS, and none of the eight (Fig. 2Bb; see below). We also determined the relationship between a experimental bees demonstrated the maximum peak at 0.01 Hz, while tethered bee’s abdominal location and its flying behavior (Fig. S1). six of the eight bees showed the maximum power at 0.0025 Hz Journal of Experimental Biology RESEARCH ARTICLE Journal of Experimental Biology (2020) 223, jeb228254. doi:10.1242/jeb.228254 (Fig. 4B). Only one bee showed a small second-maximum peak at stimulus, which was significantly lower (P=0.0274, Fisher’s exact 0.01 Hz, which was significantly different from that under the CW test). This result indicated that the bees also responded to a slow polarized stimulus (P=0.044, Fisher’s exact test). These results stimulus. However, we could not detect a 0.005 Hz peak in the indicate that the abdominal periodic movements were elicited by the averaged PS, although the power at 0.005 Hz was relatively high rotation of the polarized e-vector orientation. Taking these results compared with that under other stimulus conditions (Fig. 6C); this together,weconcluded that thetetheredflyingbeesorientedtoa could have occurred because the peak could not be clearly separated certain e-vector direction, i.e. showed polarotaxis. from the peak at 0.0025 Hz owing to data interference from unresponsive bees (Fig. 3B and Fig. 4C). Polarotaxis under different speeds of the stimulus Next, we observed polarotaxis of the tethered bees under CW rotating Selective stimulation of eye regions −1 e-vector stimulus at twice the speed (3.6 deg s ) ortwo timesslower Polarization vision in insects is known to be mediated by the DRA of −1 speed (0.9 deg s ) to confirm that the periodicity in the abdominal the compound eye. To confirm the sensory input area for polarotaxis movement (Figs 2 and 3) was not elicited by internal rhythm but by in the eye, we covered a part of each compound eye and restricted the external polarized light stimuli. Under the faster stimulus, some bees area receiving light stimulation to the DRA (Fig. 7D,E). The bees in still showed right-and-left abdominal movements synchronized to the which the DRAs were covered did not show polarotactic abdominal −1 −1 stimulus rotation (Fig. 5A). However, in contrast to the 1.8 deg s movement even under the 1.8 deg s CW rotating polarized light stimulus, the PS of the abdominal trajectory showed only a small peak stimulus to which intact bees responded (Fig. 7A), and no clear peak at a stimulus frequency of 0.02 Hz (Fig. 5B). Moreover, in the was noted at the stimulus frequency of 0.01 Hz in the PS (Fig. 7B). averaged PS of all 14 experimental bees, a small, but detectable, peak The averaged PS of all eight experimental bees did not exhibit a peak at 0.02 Hz and a maximum peak at 0.0025 Hz were noted (Fig. 5C). at 0.01 Hz (Fig. 7C), indicating that the bees with covered DRAs lost The number of bees showing the peak at 0.02 Hz in the PS was the ability to orient to certain e-vectors. Similar to the response of −1 significantly different from that experiencing the 1.8 deg s stimulus intact bees to a static stimulus, none of the eight bees displayed a −1 (seven of 14 bees for 3.6 deg s and none of the 21 bees for maximum peak at 0.01 Hz (Fig. 7C, see also Fig. 3B), and their −1 1.8 deg s stimulus; P=0.0005, Fisher’s exact test), although only response was not significantly different (P=1, Fisher’s exact test). one of the 14 experimental bees showed a maximum peak at 0.02 Hz Conversely, the number of bees showing a maximum peak at 0.01 Hz (Fig. 5C). These results indicated that the bees exhibited weak was also not significantly different from that of the intact bees under polarotaxis to the fast rotating e-vector stimulus. the CW stimulus (Fig. 3A and Fig. 7C; P=0.1421, Fisher’s exact test), Under the slower rotating stimulus, the tethered bees showed probably because of the small number of experimental bees used. clear right-and-left abdominal movements (Fig. 6A), the PS of which had a maximum peak at a stimulus frequency of 0.005 Hz PEO (Fig. 6B). Four of the ten experimental bees exhibited a maximum We assessed the PEO of the 21 bees that showed polarotaxis under cw −1 peak at 0.005 Hz in each PS of the abdominal trajectory (Fig. 6C), the 1.8 deg s CW stimulus. In addition to the 12 bees in the −1 whereas only one of the 21 bees did so under the 1.8 deg s experiments shown in Fig. 3, data from another nine bees were newly Fig. 4. Abdominal movements of Apis mellifera under a −1 CW (1.8 deg s ) + depolarizer depolarized light stimulus. (A) An example of a bee’s abdominal trajectory. A UV-transmitted depolarizer was put −1 below the rotating polarizer (1.8 deg s ), just above the bee’s head, such that the size of the light stimulus covered the entire 0 receptive field of the bee’s DRA. The lower trace (Pol.) indicates the e-vector orientation of the polarizer with respect to the bee’s body axis. The first 200 s of the trajectory (gray) was not used for –1 FFT analysis. (B) The PS of the abdominal trajectory shown in A. (C) Top: averaged PS (black line) and a histogram of the 360 deg maximum peak in each PS (gray bars) are shown (N=8). Bottom: heat map of the PSs (normalized by the maximum power) of all 0 deg 200 s experimental bees (N=8). BC 4 4 (N=8) 3 3 2 2 1 1 0 0 0.01 0.02 0.03 0.04 Frequency (Hz) 0.01 0.02 0.03 0.04 Frequency (Hz) Movement (mm) –1 Pol. Relative power (10 ) Bee ID Number of bees Journal of Experimental Biology RESEARCH ARTICLE Journal of Experimental Biology (2020) 223, jeb228254. doi:10.1242/jeb.228254 Fig. 5. Abdominal movements of Apis mellifera under a −1 CW (3.6 deg s ) −1 rotating polarized light stimulus (3.6 deg s ). (A) An example of a bee’s abdominal trajectory. The lower trace (Pol.) indicates the e-vector orientation of the polarizer with respect to the bee’s body axis. The first 200 s of the trajectory (gray) was not used for FFT analysis. (B) The PS of the abdominal –1 trajectory shown in A. (C) Averaged PS (black line) and the –2 histogram of the maximum peak in each PS (gray bars) are shown (N=14). Dashed lines indicate the peaks at the stimulus –3 rotation frequency (0.02 Hz). 360 deg 0 deg 100 s 3 3 (N=14) 2 8 1 1 0 0 0.01 0.02 0.03 0.04 0.01 0.02 0.03 0.04 Frequency (Hz) obtained from 16 bees tested in total under the CW stimulus. The DISCUSSION −1 PSs of all 37 individuals tested under the 1.8 deg s CW stimulus Behavioral response to a polarized light stimulus in the (21 bees in Fig. 3 and an additional 16 bees) are summarized in Fig. S3. honeybee The PEO of each bee varied from −90 to 90 deg (Fig. 8). However, In the present study, we showed that bees tended to orient to certain cw more than half of the bees (14 of 21) showed a PEO between −60 e-vector angles during their flight under tethered condition, i.e. they cw and 0 deg, and the distribution was not significantly random (P=0.01, referred polarized light information to control their flight direction. −1 Rayleigh test). We also tried to compare the PEO and PEO of the The fact that fewer bees responded to the fast stimulus (3.6 deg s , cw ccw −1 −1 ten bees that showed polarotaxis for both CW and CCW stimuli in the Fig. 5) than to the slow stimuli (0.9 deg s and 1.8 deg s ;Figs 2, 3 experiments shown in Fig. 3 (Fig. S4). Although some bees showed and 6) is also indicative of the use of e-vector orientation as a global similar PEOs for CW and CCW stimuli, the difference between them cue for orientation. Probably, they did not refer to the e-vector when it (PEO −PEO ) was quite varied (−3.48±37.74 deg, N=10). quickly changed because they did not expect such a situation, except cw ccw Fig. 6. Abdominal movements of Apis mellifera under a −1 CW (0.9 deg s ) −1 rotating polarized light stimulus (0.9 deg s ). (A) An example of a bee’s abdominal trajectory. The lower trace (Pol.) indicates the e-vector orientation of the polarizer with respect to the bee’s body axis. The first 200 s of the trajectory (gray) was not used for FFT analysis. (B) The PS of the abdominal trajectory shown in A. (C) Averaged PS (black line) and the histogram of the maximum peak in each PS (gray bars) are shown (N=10). Dashed lines indicate the peaks at the stimulus –1 rotation frequency (0.005 Hz). 360 deg 0 deg 400 s B C (N=10) 3 3 6 2 2 4 1 1 2 0 0 0 0.01 0.02 0.03 0.04 0.01 0.02 0.03 0.04 Frequency (Hz) Number of bees Movement (mm) Movement (mm) –1 Pol. –1 Relative power (10 ) Relative power (10 ) Pol. Number of bees Journal of Experimental Biology RESEARCH ARTICLE Journal of Experimental Biology (2020) 223, jeb228254. doi:10.1242/jeb.228254 −1 AD CW (1.8 deg s ) + DRA painting CE –1 360 deg 0 deg 200 s B E 4 4 8 (N=8) 3 3 6 2 4 1 1 2 0 0 0.01 0.02 0.03 0.04 0.01 0.02 0.03 0.04 Frequency (Hz) −1 Fig. 7. Abdominal movements of dorsal rim area (DRA)-covered Apis mellifera under a rotating polarized light stimulus (1.8 deg s ). (A) An example of a bee’s abdominal trajectory. The lower trace (Pol.) indicates the e-vector orientation of the polarizer with respect to the bee’s body axis. The first 200 s of the trajectory (gray) was not used for FFT analysis. (B) The PS of the abdominal trajectory shown in A. (C) Averaged PS (black line) and the histogram of the maximum peak in each PS (gray bars) are shown (N=8). (D) Head of a bee after its DRAs were painted. The area surrounded by the dashed line was painted. Arrowheads indicate the ocelli. C, caudal; CE, compound eye; D, dorsal; L, lateral. (E) Lateral view of the compound eye of the bee shown in D. when they quickly changed their flight direction. It is also possible review see Labhart and Meyer, 1999; Wehner and Labhart, 2006). that the fast-rotating stimulus caused an optomotor response in which In honeybees, ultraviolet (UV)-sensitive photoreceptors of the the bee steered in the same direction as the rotating stimulus at all ommatidia in the DRA are highly polarization sensitive, and their e-vector orientations. To confirm this possibility, we performed a receptive field covers a large part of the celestial hemisphere, which trend analysis for all behavioral data shown in Figs 3, 5 and 6 is suitable for observing the sky (Labhart, 1980; Wehner and (Fig. S5). If a bee showed a strong optomotor response, it should Strasser, 1985). Behaviorally, it has also been demonstrated that show a constant steering trend toward the stimulus direction. covering the DRA impairs the correct coding of food orientation However, in all stimulus conditions, the trend was varied among by the waggle dance orientation (Wehner and Strasser, 1985) and individuals, and we could not find any prominent correlations discrimination of different e-vector orientations by classical between steering and stimulus directions (Fig. S5B,C). For more conditioning (Sakura et al., 2012). These results clearly show that precise verification of the optomotor responses for the rotating bees utilize polarized light detected by the ommatidia in the DRA e-vector, comparison between the behavior under the fast CW and for orientation. CCW stimulus will be necessary. Bees in which the DRAs were covered did not show any Polarotaxis in insects polarotaxis (Fig. 7). It is well known that detection of skylight Polarotaxis in insects has been demonstrated in several species. polarization in insects is mediated by ommatidia in the DRA (for Obviously, orientation to a certain e-vector direction is a common occurrence among insect species that utilize skylight polarization for navigation. Classically, it has been tested using a treadmill device in the cricket (Gryllus campestris; Brunner and Labhart, 1987) and the –30 30 fly (Musca domestica; von Philipsborn and Labhart, 1990). Using such a device, the insect was tethered on an air-suspended ball and its –60 60 walking trajectory could be monitored through the rotation of the ball. In these species, the insect on the ball showed clear polarotactic right- and-left turns when the e-vector of the zenithal polarized light –90 stimulus was slowly rotated, as we showed in this study in flying 90 deg (N=21) honeybees. This kind of behavior does not merely demonstrate that they have polarization vision but also allowed us to clarify fundamental properties of insect polarization vision, e.g. perception through the DRA in the compound eye (Brunner and Labhart, 1987), Fig. 8. Preferred e-vector orientations (PEOs) of the bees caught at the monochromatic spectral sensitivity (Herzmann and Labahrt, 1989; hive entrance. PEOs (arrowheads) of the bees that showed polarotaxis under −1 von Philipsborn and Labhart, 1990) and sensitivity to the degree of a CW rotating stimulus (1.8 deg s ) with respect to the bee’s body axis (N=21). The distribution was not significantly random (P=0.01, Rayleigh test). polarization (Henze and Labhart, 2007). Movement (mm) –1 Pol. Relative power (10 ) Number of bees Journal of Experimental Biology RESEARCH ARTICLE Journal of Experimental Biology (2020) 223, jeb228254. doi:10.1242/jeb.228254 Funding Orientation to polarized light has been investigated in tethered This work was supported by KAKENHI from the Japan Society for the Promotion of flying insects as well by monitoring yaw-torque responses (locust, Science (15KT0106, 16K07439 and 17H05975 to M.S.; 16K07442 to R.O.) and a Schistocerca gregaria; Mappes and Homberg, 2004), flight Bilateral Joint Research Project with the Australian Research Council from the Japan orientations (monarch butterflies, Danaus plexippus; Reppert et al., Society for the Promotion of Science (CH50427010 to M.S.). 2004) or changes in body axis (Drosophila; Weir and Dickinson, Supplementary information 2012; Mathejczyk and Wernet, 2019). A potential problem in Supplementary information available online at investigating polarization vision in tethered flying insects is that https://jeb.biologists.org/lookup/doi/10.1242/jeb.228254.supplemental sometimes the tethering apparatus, including the torque meter or other recording devices, interrupts a part of the visual field of the tested References animal. In the present experiments, we succeeded in evaluating a bee’s Batschelet, E. (1981). Circular Statistics in Biology. New York: Academic Press. Bech, M., Homberg, U. and Pfeiffer, K. (2014). Receptive fields of locust brain polarotactic flight steering by simply monitoring the horizontal neurons are matched to polarization patterns of the sky. Curr. Biol. 24, 2124-2129. position of the abdominal tip that was strongly anti-correlated with the doi:10.1016/j.cub.2014.07.045 torque generated by the bee (Fig. S1). Using these methods, the entire Blum, M. and Labhart, T. (2000). Photoreceptor visual fields, ommatidial array, and visual field of the animal remained open; therefore, it had an receptor axon projections in the polarisation-sensitive dorsal rim area of the cricket compound eye. J. Comp. Physiol. A 186, 119-128. doi:10.1007/s003590050012 advantage for investigating the animal’s responses under various Brunner, D. and Labhart, T. (1987). Behavioural evidence for polarization vision in stimulus conditions. crickets. Physiol. Entomol. 12, 1-10. doi:10.1111/j.1365-3032.1987.tb00718.x Collett, M. and Carde,R.T. (2014). Navigation: many senses make efficient foraging paths. Curr. Biol. 24, R362. doi:10.1016/j.cub.2014.04.001 PEO Collett, M., Collett, T. S., Bisch, S. and Wehner, R. (1998). Local and global The PEO distribution has been reported in several species. In walking vectors in desert ant navigation. Nature 394, 269-272. doi:10.1038/28378 crickets and flies, a weak preference to an e-vector orientation Collett, T. S., Dillmann, E., Giger, A. and Wehner, R. (1992). Visual landmarks and perpendicular to their body axis has been demonstrated, although the route following in desert ants. J. Comp. Physiol. A 170, 435-442. doi:10.1007/ BF00191460 reason for this behavior was not clear (Brunner and Labhart, 1987; Couvillon, M. J., Schü rch, R. and Ratnieks, F. L. W. (2014). Dancing bees von Philipsborn and Labhart, 1990). In flying locusts and communicate a foraging preference for rural lands in high-level agri-environment Drosophila, the PEOs were randomly distributed and they did not schemes. Curr. Biol. 24, 1212-1215. doi:10.1016/j.cub.2014.03.072 show any directional preferences as a population (Mappes and Dacke, M., Nilsson, D.-E., Scholtz, C. H., Byrne, M. and Warrant, E. J. (2003). Insect orientation to polarized moonlight. Nature 424, 33. doi:10.1038/424033a Homberg, 2004; Warren et al., 2018; Mathejczyk and Wernet, 2019). Evangelista, C., Kraft, P., Dacke, M., Labhart, T. and Srinivasan, M. V. (2014). In the present study, even though the sample size might be too small Honeybee navigation: critically examining the role of the polarization compass. to conclude their heading preferences, the distribution was Philos. Trans. R. Soc. B Biol. Sci. 369, 20130037. doi:10.1098/rstb.2013.0037 Fent, K. (1986). Polarized skylight orientation in the desert ant Cataglyphis. significantly non-uniform and bees seemed to prefer e-vector J. Comp. Physiol. A 158, 145-150. doi:10.1007/BF01338557 orientations skewed left of the body axis (Fig. 8). In some bees, the Graham, P. and Cheng, K. (2009). Ants use the panoramic skyline as a visual cue PEOs under CW and CCW stimulus were quite similar (Fig. S4). during navigation. Curr. Biol. 19, R935-R937. doi:10.1016/j.cub.2009.08.015 Therefore it was possible that, at least in these bees, each bee had its Heinze, S. (2014). Polarized-light processing in insect brains: recent insights from the desert locust, the monarch butterfly, the cricket, and the fruit fly. In Polarized own PEO and used it not only as a reference for maintaining straight Light and Polarization Vision in Animal Sciences (ed. G. Horváth), pp. 61-111. flight but also to deduce its heading orientation. Further investigation Berlin-Heidelberg: Springer-Verlag. of the bees’ PEOs under CW and CCW stimuli will be necessary to Heinze, S. (2017). Unraveling the neural basis of insect navigation. Curr. Opin. confirm whether each bee had a specific PEO. Insect Sci. 24, 58-67. doi:10.1016/j.cois.2017.09.001 Heinze, S. and Homberg, U. (2007). Maplike representation of celestial e-vector Considering that central place foragers, such as honeybees, have orientations in the brain of an insect. Science 315, 995-997. doi:10.1126/science. to change their navigational directions depending on the currently available food locations, their PEOs should reflect their previous Heinze, S. and Homberg, U. (2009). Linking the input to the output: new sets of neurons complement the polarization vision network in the locust central complex. foraging experiences. In the present study, we collected bees with a J. Neurosci. 29, 4911-4921. doi:10.1523/JNEUROSCI.0332-09.2009 pollen load at the hive entrance; therefore, all experimental forager Heinze, S. and Reppert, S. M. (2011). Sun compass integration of skylight cues in bees were returners. Consequently, we could no longer assess their migratory monarch butterflies. Neuron 69, 345-358. doi:10.1016/j.neuron.2010. feeding locations when we measured their flight responses in the 12.025 Henze, M. J. and Labhart, T. (2007). Haze, clouds and limited sky visibility: laboratory. Moreover, their path-integration vector should be reset to polarotactic orientation of crickets under difficult stimulus conditions. J. Exp. Biol. a zero state in such a situation (Sommer et al., 2008), and they might 210, 3266-3276. doi:10.1242/jeb.007831 not have had a strong motivation to use polarized light cues for Herzmann, D. and Labhart, T. (1989). Spectral sensitivity and absolute threshold of navigation. To further clarify the role of polarization vision in flying polarization vision in crickets: a behavioral study. J. Comp. Physiol. A 165, 315-319. doi:10.1007/BF00619350 foragers, testing the PEOs in bees in different navigational states Homberg, U. (2008). Evolution of the central complex in the arthropod brain with will be crucial. respect to the visual system. Arthropod Struct. Dev. 37, 347-362. doi:10.1016/j. asd.2008.01.008 Acknowledgements Homberg, U., Heinze, S., Pfeiffer, K. Kinoshita, M. and el Jundi, B. (2011). We are grateful to Dr M. V. Srinivasan and Dr T. Luu for helpful advice regarding the Central neural coding of sky polarization in insects. Phil. Trans. R. Soc. B Biol. Sci. construction of the flight simulator. We also thank Dr Y. Hasegawa, Dr H. Ikeno and 366, 680-687. doi:10.1098/rstb.2010.0199 Kraft, P., Evangelista, C., Dacke, M., Labhart, T. and Srinivasan, M. V. (2011). Ms. H. Onishi for their help with measuring the torque of the flying bees. Honeybee navigation: following routes using polarized-light cues. Phil. Trans. R. Soc. B Biol. Sci. 366, 703-708. doi:10.1098/rstb.2010.0203 Competing interests Labhart, T. (1980). Specialized photoreceptors at the dorsal rim of the honeybee’s The authors declare no competing or financial interests. compound eye: polarizational and angular sensitivity. J. Comp. Physiol. A 141, 19-30. doi:10.1007/BF00611874 Author contributions Labhart, T. (1988). Polarization-opponent interneurons in the insect visual system. Conceptualization: N.K., R.O., M.S.; Methodology: N.K., R.O., M.S.; Software: N.K., Nature 331, 435-437. doi:10.1038/331435a0 R.O.; Validation: N.K., R.O., M.S.; Formal analysis: N.K., R.O., M.S.; Investigation: Labhart, T. and Meyer, E. P. (1999). Detectors for polarized skylight in insects: a N.K., R.O., M.S.; Data curation: R.O., M.S.; Writing - original draft: M.S.; Writing - survey of ommatidial specializations in the dorsal rim area of the compound eye. review & editing: N.K., R.O., M.S.; Visualization: R.O., M.S.; Supervision: M.S.; Microsc. Res. Tech. 47, 368-379. doi:10.1002/(SICI)1097-0029(19991215)47: Project administration: M.S.; Funding acquisition: R.O., M.S. 6<368::AID-JEMT2>3.0.CO;2-Q Journal of Experimental Biology RESEARCH ARTICLE Journal of Experimental Biology (2020) 223, jeb228254. doi:10.1242/jeb.228254 Luu, T., Cheung, A., Ball, D. and Srinivasan, M. V. (2011). Honeybee flight: a novel Taylor, G. J., Luu, T., Ball, D. and Srinivasan, M. V. (2013). Vision and air flow ’streamlining’ response. J. Exp. Biol. 214, 2215-2225. doi:10.1242/jeb.050310 combine to streamline flying honeybees. Sci. Rep. 3, 2614. doi:10.1038/ Mappes, M. and Homberg, U. (2004). Behavioral analysis of polarization vision in srep02614 tethered flying locusts. J. Comp. Physiol. A Neuroethol. Sens Behav. Physiol. 190, von Frisch, K. (1967). The Dance Language and Orientation of Bees. Cambridge: 61-68. doi:10.1007/s00359-003-0473-4 Belknap Press. Mathejczyk, T. F. and Wernet, M. F. (2019). Heading choices of flying Drosophila von Philipsborn, A. and Labhart, T. (1990). A behavioural study of polarization under changing angles of polarized light. Sci. Rep. 9, 16773. doi:10.1038/s41598- vision in the fly, Musca domestica. J. Comp. Physiol. A 167, 737-743. doi:10.1007/ 019-53330-y BF00189764 Meyer, E. P. and Labhart, T. (1981). Pore canals in the cornea of a functionally Warren, T. L., Weir, P. T. and Dickinson, M. H. (2018). Flying Drosophila specialized area of the honey bee’s compound eye. Cell Tissue Res. 216, melanogaster maintain arbitrary but stable headings relative to the angle of 491-501. doi:10.1007/BF00238646 Narendra, A., Gourmaud, S. and Zeil, J. (2013). Mapping the navigational polarized light. J. Exp. Biol. 221, jeb177550. doi:10.1242/jeb.177550 Wehner, R. (1994). The polarization-vision project: championing organismic knowledge of individually foraging ants, Myrmecia croslandi. Proc. R. Soc. B Biol. Sci. 280, 20130683. doi:10.1098/rspb.2013.0683 biology. In Neural Basis of Behavioural Adaptation (ed. K. Schildberger and N. Reppert, S. M., Zhu, H. and White, R. H. (2004). Polarized light helps monarch Elsner), pp. 103-143. Stuttgart: Fischer-Verlag. butterflies navigate. Curr. Biol. 14, 155-158. doi:10.1016/j.cub.2003.12.034 Wehner, R. (1997). The ant’s celestial compass system: spectral and polarization Rossel, S. and Wehner, R. (1982). The bee’s map of e-vector pattern in the sky. channels. In Orientation and Communication in Arthropods (ed. M. Lehrer), pp. Proc. Natl. Acad. Sci. USA 79, 4451-4455. doi:10.1073/pnas.79.14.4451 145-185. Basel: Birkhä user Verlag. Rossel, S. and Wehner, R. (1984). Celestial orientation in bees: the use of spectral Wehner, R. (2003). Desert ant navigation: how miniature brains solve complex cues. J. Comp. Physiol. A 155, 605-613. doi:10.1007/BF00610846 tasks. J. Comp. Physiol. A 189, 579-588. doi:10.1007/s00359-003-0431-1 Rossel, S. and Wehner, R. (1986). Polarization vision in bees. Nature 323, Wehner, R. and Labhart, T. (2006). Polarization vision. In Invertebrate Vision (ed. E. 128-131. doi:10.1038/323128a0 Warrant and D. E. Nilsson), pp. 291-348. Cambridge: Cambridge University Rossel, S. and Wehner, R. (1987). The bee’s e-vector compass. In Neurobiology Press. and Behavior of Honeybees (ed. R. Menzel and A. Mercer), pp. 76-93. Berlin: Wehner, R. and Muller, M. (2006). The significance of direct sunlight and polarized Springer-Verlag. Sakura, M., Lambrinos, D. and Labhart, T. (2008). Polarized skylight navigation in skylight in the ant’s celestial system of navigation. Proc. Natl. Acad. Sci. USA 103, insects: model and electrophysiology of e-vector coding by neurons in the central 12575-12579. doi:10.1073/pnas.0604430103 complex. J. Neurophysiol. 99, 667-682. doi:10.1152/jn.00784.2007 Wehner, R. and Strasser, S. (1985). The POL area of the honey bee’s eye: Sakura, M., Okada, R. and Aonuma, H. (2012). Evidence for instantaneous e- behavioural evidence. Physiol. Entomol. 10, 337-349. doi:10.1111/j.1365-3032. vector detection in the honeybee using an associative learning paradigm. 1985.tb00055.x Proc. R. Soc. B Biol. Sci. 279, 535-542. doi:10.1098/rspb.2011.0929 Wehner, R., Michel, B. and Antonsen, P. (1996). Visual navigation in insects: Sommer, S., von Beeren, C. and Wehner, R. (2008). Multiroute memories in desert coupling of egocentric and geocentric information. J. Exp. Biol. 199, 129-140. ants. Proc. Natl. Acad. Sci. USA 105, 317-322. doi:10.1073/pnas.0710157104 Weir, P. T. and Dickinson, M. H. (2012). Flying Drosophila orient to sky polarization. Stalleicken, J., Mukhida, M., Labhart, T., Wehner, R., Frost, B. and Mouritsen, H. Curr. Biol. 22, 21-27. doi:10.1016/j.cub.2011.11.026 (2005). Do monarch butterflies use polarized skylight for migratory orientation? Weir, P. T., Henze, M. J., Bleul, C., Baumann-Klausener, F., Labhart, T. and J. Exp. Biol. 208, 2399-2408. doi:10.1242/jeb.01613 Dickinson, M. H. (2016). Anatomical reconstruction and functional imaging reveal Strutt, H. J. W. (1871). XV.On the light from the sky, its polarization and colour. an ordered array of skylight polarization detectors in Drosophila. J. Neurosci. 36, Lond. Edinb. Dublin Philos. Mag. J. Sci. 41, 107-120. doi:10.1080/ 14786447108640452 5397-5404. doi:10.1523/JNEUROSCI.0310-16.2016 Journal of Experimental Biology
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