Current Biology

Visual navigation in ants has long been a focus of experimental study [1-3], but only recently have explicit hypotheses about the underlying neural circuitry been proposed [4]. Indirect evidence suggests the mushroom bodies (MB), a known site of olfactory learning [5-10], may also be the substrate for visual memory in navigation tasks [11-14]. Computational modelling shows that MB neural architecture could support this function [15, 16], though there is no direct evidence that ants require MBs for visual navigation. Here we show that lesions of MB calyces impair ants visual navigation to a remembered food location whilst leaving their innate responses to visual cues unaffected. Ants are innately attracted to a large visual cue but we trained them to locate a food source at a specific angle to this visual cue. Subsequent bilateral or unilateral lesioning (through procaine hydrochloride injection) of the MB calyces, caused ants to revert to their innate cue attraction whilst control (saline) injected ants still approached the feeder. The ants path straightness and walking speed were unaffected by lesions. Reversion towards the cue direction occurred irrespective of whether it was ipsi-or contralateral to the lesion site, showing this is not due simply to an induced motor bias. Monocular occlusion did not diminish ants ability to locate the feeder, suggesting the lesion is not merely interrupting visual input to the calyx. The demonstrated dissociation between innate and learnt visual responses provides direct evidence for a specific role of the MB in navigational memory.

Cell morphogenesis is crucial for the physiology of animals and fungi alike. While animals typically shape their cells using the actin cytoskeleton, fungi control cell shape through polarized deposition of new cell wall material, which is inflated by intracellular osmotic "turgor" pressure. Understanding where and when these mechanisms evolved is essential for understanding the evolution of cell morphogenesis. To this end, we study chytrid fungi, which have a cell type that lacks a cell wall (the "zoospore") and a cell type that has a cell wall (the "sporangium"). While chytrid sporangia rely on polarized cell wall growth to control shape, we previously showed that the "frog-killing" chytrid fungus Batrachochytrium dendrobatidis (Bd) uses actin to control zoospore shape. Whether either zoospores or sporangia also use intracellular pressure regulation in cell shape control remains an open question. Here, we use live-cell imaging, environmental perturbations, and small molecule inhibitors to show that Bd sporangia generate and maintain turgor pressure, while Bd zoospores use specialized organelles called contractile vacuoles to pump water out of the cell, thereby keeping internal pressure low. Because chytrid fungi diverged prior to the evolution of the Dikarya--the fungal group comprising yeast, mushrooms, and filamentous fungi--these findings suggest that turgor pressure evolved early, and that cell morphogenesis underwent a major transition during early fungal evolution. We also suggest that the last common fungal ancestor may have, like chytrid fungi, employed stage-specific strategies for cell shape control--illustrating how developmental flexibility in cellular mechanisms can serve as a wellspring of evolutionary innovation.

Cellularization is the coordinated division of a multinucleate cytoplasm into many cells.1-3 Multinucleation is a common life cycle strategy observed across eukaryotic lineages, including in microbial eukaryotes, fungi, plants and animals, and is associated with the ability to transition to a unicellular state through cellularization.4 In the best-studied model for this process, Drosophila melanogaster, cellularization requires the coordinated action of actin and microtubule (MT) networks to bring about the synchronous invagination of plasma membrane furrows, but the extent of conservation of these mechanisms across eukaryotes remains unknown.1,5,6 Here we investigate cellularization in the ichthyosporean Sphaeroforma arctica, a close relative of animals with a multinucleate life cycle stage.7-9 Using live cell imaging, ultrastructure expansion microscopy (U-ExM) and volume electron microscopy, we define the membrane, MT and actin dynamics that accompany cellularization in S. arctica. Using pharmacological inhibitors and centrifugation, we show that MTs, in addition to positioning nuclei, play a role in guiding nascent furrows to sustain equi-partitioning of nuclei and cytoplasm between daughter cells. Our findings indicate that cellularization is regulated through crosstalk between actin and MT networks, exhibiting mechanistic parallels with canonical cytokinesis, and establish S. arctica as a valuable model for investigating general principles of cellularization.

Myosin 2-dependent actin contractility drives essential cell functions including fast crawling motility in animal cells, Dictyostelium amoebae, and other species from the Amorphea lineage. Whether and how species outside this single eukaryotic group can generate contractile actin networks has been largely unexplored. We demonstrate that Naegleria, an amoeba from the Heterolobosea--an evolutionarily distant eukaryotic lineage that includes the fastest known crawling eukaryotes--expresses three distinct Myosin 2 homologs. Using biochemical assays and immunofluorescence, we show that these Myosin 2 proteins bind cellular actin networks and that these networks generate ATP-dependent contractility. By identifying additional Myosin 2 homologs in dozens of additional heterolobosean amoebae (but not obligate flagellates), we find a widespread correlation within this group between crawling behavior and contractile actin networks. This correlation includes the amoeba Vahlkampfia avara, which we demonstrate can crawl at speeds exceeding 180 m/min and has contractile actin networks and Myosin 2 homologs. These findings show that Myosin 2-driven contractility exists beyond Amorphea and is associated with diverse, fast-crawling cell types. Expanding the taxonomic breadth of actin network contractility impacts our basic understanding of cell motility, evolutionary biology, and of the fundamental biology of human pathogens that rely on fast cell migration.

Psilocybin is a psychoactive compound with clinical applications produced by dozens of mushroom species1. There has been a longstanding interest in psilocybin research with regard to treatment for addiction2, depression3, and end-of-life suffering4. However, until recently very little was known about psilocybin biosynthesis and its ecological role. Here we confirm and refine recent findings5 about the genes underpinning psilocybin biosynthesis, discover that there is more than one psilocybin biosynthesis cluster in mushrooms, and we provide the first data directly addressing psilocybins ecological role. By analysing independent genome assemblies for the hallucinogenic mushrooms Psilocybe cyanescens and Pluteus salicinus we recapture the recently discovered psilocybin biosynthesis cluster5,6 and show that a transcription factor previously implicated in its regulation is actually not part of the cluster. Further, we show that the mushroom Inocybe corydalina produces psilocybin but does not contain the established biosynthetic cluster, and we present an alternative cluster. Finally, a meta-transcriptome analysis of wild-collected mushrooms provides evidence for intra-mushroom insect gene expression of flies whose larvae grow inside Psilocybe cyanescens. These larvae were successfully reared into adults. Our results show that psilocybin does not confer complete protection against insect mycophagy, and the hypothesis that it is produced as an adaptive defense compound may need to be reconsidered.

The C. elegans receptor CED-1, along with orthologs mammalian MEGF10 and Drosophila Draper, plays a well-established and conserved role in phagocytosis by acting in engulfing cells.1-7 Interestingly, CED-1 family members are also expressed in neurons, but their functions in these non-engulfing cells remain unclear.6,8,9 Our study shows that CED-1 localizes to the dendrites and primary cilia of male tail RnB neurons, which mediate sensory perceptions during mating10 and generate extracellular vesicles (EVs) that transfer bioactive macromolecules for both intercellular and animal-to-animal communication.11 Loss of ced-1 leads to a reduction in the shedding of EVs that contain the transient receptor potential (TRP) channel PKD-2 from the cilium distal tip, and this is rescued by the expression of CED-1 in the neurons. CED-1 is required to increase both the abundance of PKD-2 in the cilium and PKD-2 EV shedding in response to the physiological stimulus of mating partners. Assessment of ced-1 mutant male mating indicates that neuronal CED-1 is also important for turning behavior, which helps the male tail to maintain contact with a mate. Collectively, these results reveal a new role for CED-1 in neurons as a regulator of EV biogenesis in response to environmental cues, optimizing the shedding of bioactive EVs for effective communication.

Perhaps nothing is stronger evidence of the importance of sleep than its conservation across animals [1], but the extent of its regulatory conservation is unknown. The upside-down jelly-fish Cassiopea xamachana sleeps [2], and this behavior is controlled by radially-spaced marginal ganglia. After defining a sleep-wake threshold, we compared gene expression profiles of ganglia from animals sleep-deprived for two nights and found differential expression in many sleep-related genes including GABAergic, melatonergic, and cholinergic receptors. We focused on a nicotinic acetylcholine receptor alpha subunit-like (Chrnal-E), based on its differential expression, and selected animals for a second round of RNAseq that included both light-based and mechanically-based sleep-deprivation. Combining datasets revealed a short list of differentially expressed genes, of which chrnal-E is the most recognizable and well-supported, so we investigated its potential role in sleep regulation. First, we found that chemical cholinergic neuromodulators positively regulate pacemaker activity. Then, we showed by in situ hybridization that chrnal-E is expressed primarily within the ganglia, and that the area of expression expands after sleep deprivation. Next, we developed RNAi for use in Cassiopea and determined that Chrnal-E promotes wakefulness. Finally, we sampled circadian timepoints in the field and found in control conditions, chrnal-E has lowest expression late at night, but in sleep deprived animals, chrnal-E peaks at this time, supporting a link to wakefulness. Our finding that Cassiopea sleep is regulated by the cholinergic system underscores that mechanisms of sleep conservation are deeply conserved in animal evolution.

Sleep in animals plays roles that appear specific to the brain, including synaptic homeostasis [1], neurotransmitter regulation [2], cellular repair [3], memory consolidation [4], and neural plasticity [5,6]. Would any of these functions of sleep be relevant to an animal without a brain? The upside-down jellyfish Cassiopea xamachana, like other cnidarians, lacks a centralized nervous system, yet the animal sleeps [7]. By tracking the propensity of the radially spaced ganglia to initiate muscle contractions over several days we determined how neural activity changes between sleep and wake in a decentralized nervous system. Ganglia-network sleep/ wake activity patterns range from being highly specialized to a few ganglia, to being completely unspecialized. Ganglia specialization also changes over time, indicating a high degree of plasticity in the neural network. The ganglia that lead activity can persist or switch between sleep/wake transitions, signifying a level of local control of the behavioral state in a decentralized nervous system. Following sleep deprivation, ganglia usage becomes far more sleep specialized, demonstrating reduced network plasticity. Together, these findings identify a novel behavioral control system that is decentralized and yet displays temporal specialization and centralization, and show a role for sleep in maintaining neural network plasticity, revealing a conserved function of sleep in this brain-less animal.

Male/hermaphrodite species have arisen multiple times from a male/female ancestral state in nematodes, providing a model to study behavioral adaptations to different reproductive strategies. Here we examined the mating behaviors of male/female (gonochoristic) Caenorhabditis species in comparison to male/hermaphrodite (androdiecious) close relatives. We find that females from two species in the Elegans group chemotax to volatile odor from males, a behavior described in only a few animal species. The females also display known mating-receptive behaviors such as sedation when male reproductive structures contact the vulva. Focusing on the male/female species C. nigoni, we show that female chemotaxis to males is limited to adult females approaching adult or near-adult males, and relies upon the AWA neuron-specific transcription factor ODR-7, as does male chemotaxis to female odor as previously shown in C. elegans. However, female receptivity during mating contact is odr-7-independent. All female behaviors are suppressed by mating, and all are absent in young hermaphrodites from the sister species C. briggsae. However, latent receptivity during mating contact can be uncovered in mutant or aged C. briggsae hermaphrodites that lack self-sperm. Young hermaphrodites from a second androdioecious species, C. tropicalis, are similarly unreceptive to males, but recover all female behaviors upon aging. These results reveal two mechanistically distinct components of the shift from female to hermaphrodite behavior: the loss of female-specific odr-7-dependent chemotaxis, and a sperm-dependent state of reduced receptivity to mating contact. The recovery of receptivity after sperm depletion has the potential to maximize hermaphrodite fitness across the lifespan. HighlightsO_LIFemale and hermaphrodite mating behaviors differ in closely related nematode species C_LIO_LIFemales are attracted to volatile male odors, but hermaphrodites are not C_LIO_LIThe same olfactory neuron pair drives female attraction to males and vice versa C_LIO_LILatent female mating behaviors are revealed in hermaphrodites that lack self-sperm C_LI

Extracellular vesicles (EVs) are emerging as a universal means of cell-to-cell communication and hold great potential in diagnostics and regenerative therapies [1]. An urgent need in the field is a fundamental understanding of physiological mechanisms driving EV generation and function. Ciliary EVs act as signaling devices in Chlamydomonas and C. elegans [2-4]. Mammalian cilia shed EVs to eliminate unwanted receptors [5] or to retract cilia before entering the cell cycle [6]. Here we used our established C. elegans model to study sensory-evoked ciliary EV release and targeting using a fluorescently labeled EV cargo polycystin-2 (PKD-2). In C. elegans and mammals, the Autosomal Dominant Polycystic Kidney Disease (ADPKD) gene products polycystin-1 and polycystin-2 localize to cilia and EVs, act in the same genetic pathway, and function in a sensory capacity, suggesting ancient conservation [7]. We find that males deposit PKD-2-carrying EVs onto the vulva of the hermaphrodite during mating. We also show that mechanical stimulation triggers release of PKD-2-carrying EVs from cilia. To our knowledge this is the first report of mechanoresponsive nature of the ciliary EV release and of ciliary EV directional transfer from one animal to another animal. Since the polycystins are evolutionarily conserved ciliary EV cargoes, our findings suggest that similar mechanisms for EV release and targeting may occur in other systems and biological contexts.

Memory reactivation during NonREM-ripples is thought to communicate new information to a systems-wide network. Cortical high frequency events have also been described that co-occur with ripples. Focusing on NonREM sleep after different behaviors, both hippocampal ripples and parietal high frequency oscillations were detected. A bimodal frequency distribution was observed in the parietal high frequency events, faster and slower, with increases in prefrontal directionality measured by Granger causality analysis specifically seen during the fast parietal oscillations. Furthermore, fast events activated prefrontal-parietal cortex whereas slow events activated hippocampal-parietal areas. Finally, there was a learning-induced increase in both number and size of fast high frequency events. These patterns were not seen after novelty exposure or foraging, but occurred after the learning of a new goal location in a maze. Disruption of either sleep or hippocampal ripples impaired long-term memory consistent with these having a role in memory consolidation.

The nearly constant downward force of gravity has powerfully shaped the behaviors of many organisms [1]. Walking flies readily orient against gravity in a behavior termed negative gravitaxis. In Drosophila this behavior is studied by observing the position of flies in vials [2-4] or simple mazes [5-9]. These assays have been used to conduct forward-genetic screens [5, 6, 8] and as simple tests of locomotion deficits [10-12]. Despite this long history of investigation, the sensory basis of gravitaxis is largely unknown [1]. Recent studies have implicated the antennae as a major mechanosensory input [3, 4], but many details remain unclear. Fly orientation behavior is expected to depend on the direction and amplitude of the gravitational pull, but little is known about the sensitivity of flies to these features of the environment. Here we directly measure the gravity-dependent orientation behavior of flies walking on an adjustable tilted platform, that is inspired by previous insect studies [13-16]. In this arena, flies can freely orient with respect to gravity. Our findings indicate that flies are exquisitely sensitive to the direction of gravitys pull. Surprisingly, this orientation behavior does not require antennal mechanosensory input, suggesting that other sensory structures must be involved.

Path integration is a computational strategy that allows an animal to maintain an internal estimate of its position relative to a point of origin. Many species use path integration to navigate back to specific locations, typically their homes, after lengthy and convoluted excursions. Hymenopteran insects are impressive path integrators, directly returning to their hives after hundreds of meters of outward travel. Recent neurobiological insights have established hypotheses for how path integration may be mediated by the brains of bees, but clear ways to test these hypotheses in the laboratory are currently unavailable. Here we report that the bumblebee, Bombus terrestris, uses path integration while walking over short distances in an indoor arena. They estimate accurate vector distances after displacement and orient by artificial celestial cues. Walking bumblebees also exhibited systematic search patterns when home vectors failed to lead them accurately back to the nest, closely resembling searches performed by other species in natural conditions. We thus provide a robust experimental system to test navigation behavior in the laboratory that reflects most aspects of natural path integration. Importantly, we established this assay in an animal that is both readily available and resilient to invasive manipulations. In the future, our behavioral assay therefore can be combined with current electrophysiological techniques, opening a path towards directly probing the neural basis of the sophisticated vector navigation abilities of bees.

The mutualism between clownfishes (or anemonefishes) and their giant host sea anemones are among the most immediately recognizable animal interactions on the planet and have attracted a great deal of popular and scientific attention [1-5]. However, our evolutionary understanding of this iconic symbiosis comes almost entirely from studies on clownfishes-- a charismatic group of 28 described species in the genus Amphiprion [2]. Adaptation to venomous sea anemones (Anthozoa: Actiniaria) provided clownfishes with novel habitat space, ultimately triggering the adaptive radiation of the group [2]. Clownfishes diverged from their free-living ancestors 25-30 MYA with their adaptive radiation to sea anemones dating to 13.2 MYA [2, 3]. Far from being mere habitat space, the host sea anemones also receive substantial benefits from hosting clownfishes, making the mutualistic and co-dependent nature of the symbiosis well established [4, 5]. Yet the evolutionary consequences of mutualism with clownfishes have remained a mystery from the host perspective. Here we use bait-capture sequencing to fully resolve the evolutionary relationships among the 10 nominal species of clownfish-hosting sea anemones for the first time (Figure 1). Using time-calibrated divergence dating analyses we calculate divergence times of less than 25 MYA for each host species, with 9 of 10 host species having divergence times within the last 13 MYA (Figure 1). The clownfish-hosting sea anemones thus diversified coincidently with clownfishes, potentially facilitating the clownfish adaptive radiation, and providing the first strong evidence for co-evolutionary patterns in this iconic partnership. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=187 SRC="FIGDIR/small/576469v1_fig1.gif" ALT="Figure 1"> View larger version (58K): org.highwire.dtl.DTLVardef@7053b4org.highwire.dtl.DTLVardef@876c65org.highwire.dtl.DTLVardef@dd6d9forg.highwire.dtl.DTLVardef@147fddd_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Diversification of the clownfish-hosting sea anemones was coincident with the clownfish adaptive radiation. A) Time-calibrated maximum likelihood cladogram of Order Actiniaria based on 328 ultra-conserved element and exon loci (75% data occupancy matrix). The three clades containing the clownfish hosting sea anemones are highlighted reflecting the multiple evolutionary origins of symbiosis with clownfishes within superfamily Actinioidea. B-D) Detailed time-calibrated maximum likelihood cladograms of Entacmaea quadricolor, Clade Stichodactylina, and Clade Heteractina, respectively. In all panels, the orange line denotes the beginning of the clownfish adaptive radiation 13 MYA. Sea anemone superfamilies Actinostoloidea, Metridioidea, Actiniernoidea, and Edwardsioidea are collapsed for clarity. C_FIG

Meristems are generative centres with stem cells from which the bodies of land plants develop. Marchantia polymorpha spores are single cell structures formed at meiosis. On germination, spores divide asymmetrically to form a basal cell that terminally differentiates and an apical germ cell that divides into an early cell mass on which a flat prothallus develops. A single stem cell niche (meristem) forms de novo at the margin of the prothallus to drive development of the thallus plant body. Here we show that the prothallus forms at the apical pole of the early cell mass and represses the formation of other prothalli. LOW AUXIN RESPONSIVE (MpLAXR) marks this apical pole indicating that an auxin minimum is located at the site of organogenesis. Light is required for the formation of the apical auxin minimum and for the development of the prothallus from the early cell mass. Disrupting the apical auxin minimum by exogenous auxin treatment suppresses the transitions to the prothallus and formation of the meristem from the early cell mass. A similar molecular program operates during plant regeneration from a single differentiated thallus cell, which regains stemness (pluripotency) upon surgical isolation from surrounding tissues; the isolated cell divides forming an early cell mass that develops a local auxin minimum where a flat prothallus with a single meristem forms. We conclude that a light-dependent, apical auxin minimum is required for the formation of the prothallus and the de novo development of the first meristem in Marchantia polymorpha. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/665278v2_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@c3c93org.highwire.dtl.DTLVardef@15d061borg.highwire.dtl.DTLVardef@3beacdorg.highwire.dtl.DTLVardef@1b45fd4_HPS_FORMAT_FIGEXP M_FIG C_FIG

In the mammalian olfactory system, crosstalk among diverse olfactory signals is minimized through labelled line coding: individual neurons express one or few olfactory receptors among those encoded in the genome. Labelled line coding allows for separation of stimuli during mammalian olfactory signal transduction, however, in the nematode worm Caenorhabditis elegans, 1,300 olfactory receptors are primarily expressed in only 32 neurons, precluding this strategy. Here we report genetic, pharmacological and behavioural evidence that {beta}-arrestin-mediated desensitization of olfactory receptors, working downstream of the kinase GRK-1, enables discrimination between intra-neuronal olfactory stimuli, but that this discrimination relies on quantitative, rather than qualitative differences in signalling. Our findings suggest that C. elegans exploits {beta}-arrestin desensitization to maximize responsiveness to novel odors, allowing for behaviourally appropriate responses to olfactory stimuli despite the large number of olfactory receptors signalling in single cells. This represents a fundamentally different solution to the problem of olfactory discrimination than that which evolved in mammals, allowing for economical use of an extremely limited number of sensory neurons.

Centuries of zoological studies amassed billions of specimens in collections worldwide. Genomics of these specimens promises to rejuvenate biodiversity research. The obstacles stem from DNA degradation with specimen age. Overcoming this challenge, we set out to resolve a series of long-standing controversies involving a group of butterflies. We deduced geographical origins of several ancient specimens of uncertain provenance that are at the heart of these debates. Here, genomics tackles one of the greatest problems in zoology: countless old, poorly documented specimens that serve as irreplaceable embodiments of species concepts. The ability to figure out where they were collected will resolve many on-going disputes. More broadly, we show the utility of genomics applied to ancient museum specimens to delineate the boundaries of species and populations, and to hypothesize about genotypic determinants of phenotypic traits.

One remarkable feature of the nervous system is its ability to rapidly and spontaneously switch between activity states. In the extreme example of sleep, animals arrest locomotion, reduce their sensitivity to sensory stimuli, and dramatically alter their neural activity. Small organisms are useful models to better understand these sudden changes in neural states because we can simultaneously observe whole-brain activity, monitor behavior and precisely regulate the external environment. Here, we show a spontaneous sleep-like behavior in C. elegans that is associated with a distinct global-brain state and regulated by both the animals internal physiological state and input from multiple sensory circuits. Specifically, we found that when confined in microfluidic chambers, adult worms spontaneously transition between periods of normal activity and short quiescent bouts, with behavioral state transitions occurring every few minutes. This quiescent state, which we call Sleep, meets the behavioral requirements of C. elegans sleep, is dependent on known sleep-promoting neurons ALA and RIS, and is associated with a global down-regulation of neural activity. Consistent with prior studies of C. elegans sleep, we found that Sleep is regulated by satiety and temperature. In addition, we show for the first time that quiescence can be either driven or suppressed by thermosensory input, and that animal restraint induces quiescence through mechanosensory pathways. Together, these results establish a rich model system for studying how neural and behavioral state transitions are influenced by multiple physiological and environmental conditions. Significance StatementUnique brain states govern animal behaviors like sleep and wakefulness; however, how the brain regulates these dramatic state transitions is not well understood. Brain activity can be influenced by a complex interaction between sensory circuits that monitor the external environment, neural circuits that control behavior, and internal chemical signaling. Here, we describe a platform to study behavioral states in a context that allows us to record whole-brain activity while controlling the environment and monitoring animal behavior. Specifically, we identify a pattern of sleep bouts in the roundworm C. elegans that occur when they are confined to microscopic fluidic chambers. This behavior platform provides a powerful system to study how neural circuits interact with chemical signaling to drive brain state transitions.

Honey bees routinely fly hundreds or thousands of meters between their hive and established foraging locations [1-3]. To navigate these long distances, they are known to combine both landmark use [4-7] and path integration [8-11] and have been hypothesized to build a cognitive map [12-14]. Due to technical challenges inherent in tracking these small insects, obtaining three-dimensional, high-resolution measurements of individual navigational precision, and thus a detailed understanding of their strategies, has been difficult. Here, we utilize a novel multicopter drone-based tracking system [15] to measure the individual flight paths of honey bees in a structured agricultural landscape at unprecedented spatial and temporal resolution. Although bees could choose from multiple routes, we discovered that individual bees follow idiosyncratic paths with striking and repeatable precision. Flight path variability was highest over visually sparse regions and lowest near prominent proximal landmarks. Furthermore, individual strategies differed: some bees flew directly toward the hive before maneuvering around a specific tree, while others flew directly to a gap between a hedgerow and the tree. Thus, each animal varies in how it uses visual information and selects between behavioral strategies. The level of precision exhibited by their flight paths exceeds that reported in the waggle dance, implying that dance variability does not reflect a limit in the bees underlying spatial representation. Our results demonstrate the remarkable precision of individual bee navigation and illustrate the potential of this new drone-based tracking method to illuminate fine-scale behavioral mechanisms across a spectrum of honey bee ecology and cognition. HighlightsO_LIIndividual honey bees follow strikingly precise, idiosyncratic flight paths, revealing personalized strategies for navigating complex, obstacle-rich landscapes. C_LIO_LIVariability in individual bee flight paths was lower near conspicuous landmarks, but greater when further from such features, as a consequence variability in bee flights was not uniform along a route. C_LIO_LINavigational precision far exceeds waggle dance variability, showing that dance imprecision is not constrained by limits in spatial representation. C_LIO_LIMulticopter drone-based tracking method enables new investigations of 3D flight control and visual navigation in structurally complex realistic environments. C_LI

Target interception is a complex sensorimotor behavior which requires fine tuning of the sensory system and its strategic coordination with the motor system. Despite various theories about how interception is achieved, its neural implementation remains unknown. We have previously shown that hunting dragonflies employ a balance of reactive and predictive control to intercept prey, using sophisticated model driven predictions to account for expected prey and self-motion. Here we explore the neural substrate of this interception system by investigating a well-known class of target-selective descending neurons (TSDNs). These cells have long been speculated to underlie interception steering but have never been studied in a behaving dragonfly. We combined detailed neuroanatomy, high-precision kinematics data and state-of-the-art neural telemetry to measure TSDN activity during flight. We found that TSDNs are exquisitely tuned to prey angular size and speed at ethological distances, and that they synapse directly onto neck and wing motoneurons in an unusual manner. However, we found that TSDNs were only weakly active during flight and are thus unlikely to provide the primary steering signal. Instead, they appear to drive the foveating head movements that stabilize prey on the eye before and likely throughout the interception flight. We suggest the TSDN population implements the reactive portion of the interception steering control system, coordinating head and wing movements to compensate for unexpected prey motion.