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Puchalski A, McCarthy Z, Palaoro AV, Salamatin AA, Nagy-Mehesz A, Korneva G, Beard CE, Owens J, Adler PH, Kornev KG. Flexural rigidity of hawkmoth antennae depends on the bending direction. Acta Biomater 2024:S1742-7061(24)00350-7. [PMID: 38944324 DOI: 10.1016/j.actbio.2024.06.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 06/04/2024] [Accepted: 06/24/2024] [Indexed: 07/01/2024]
Abstract
To probe its environment, the flying insect controllably flexes, twists, and maneuvers its antennae by coupling mechanical deformations with the sensory output. We question how the materials properties of insect antennae could influence their performance. A comparative study was conducted on four hawkmoth species: Manduca sexta, Ceratomia catalpae, Manduca quinquemaculata, and Xylophanes tersa. The morphology of the antennae of three hawkmoths that hover while feeding and one putatively non-nectar-feeding hawkmoth (Ceratomia catalpa) do not fundamentally differ, and all the antennae are comb-like (i.e., pectinate), markedly in males but weakly in females. Applying different weights to the free end of extracted cantilevered antennae, we discovered anisotropy in flexural rigidity when the antenna is forced to bend dorsally versus ventrally. The flexural rigidity of male antennae was less than that of females. Compared with the hawkmoths that hover while feeding, Ceratomia catalpae has almost two orders of magnitude lower flexural rigidity. Tensile tests showed that the stiffness of male and female antennae is almost the same. Therefore, the differences in flexural rigidity are explained by the distinct shapes of the antennal pectination. Like bristles in a comb, the pectinations provide extra rigidity to the antenna. We discuss the biological implications of these discoveries in relation to the flight habits of hawkmoths. Flexural anisotropy of antennae is expected in other groups of insects, but the targeted outcome may differ. Our work offers promising new applications of shaped fibers as mechanical sensors. STATEMENT OF SIGNIFICANCE: Insect antennae are blood-filled, segmented fibers with muscles in the two basal segments. The long terminal segment is muscle-free but can be flexed. Our comparative analysis of mechanical properties of hawkmoth antennae revealed a new feature: antenna resistance to bending depends on the bending direction. Our discovery replaces the conventional textbook scenario considering hawkmoth antennae as rigid rods. We showed that the pectinate antennae of hawkmoths behave as a comb in which the bristles resist bending when they come together. This anisotropy of flexural resistance offers a new mode of environmental sensing that has never been explored. The principles we found apply to other insects with non-axisymmetric antennae. Our work offers new applications for shaped fibers that could be designed to sense the flows.
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Affiliation(s)
- Adam Puchalski
- Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina, USA, 29634
| | - Zoë McCarthy
- Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina, USA, 29634
| | | | - Arthur A Salamatin
- Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina, USA, 29634
| | - Agnes Nagy-Mehesz
- Department of Bioengineering, Clemson University, Clemson, South Carolina USA, 29634
| | - Guzeliya Korneva
- Department of Bioengineering, Clemson University, Clemson, South Carolina USA, 29634
| | - Charles E Beard
- Department of Plant and Environmental Sciences, Clemson University, Clemson, South Carolina USA, 29634
| | - Jeffery Owens
- Air Force Civil Engineer Center, Tyndall Air Force Base, Florida
| | - Peter H Adler
- Department of Plant and Environmental Sciences, Clemson University, Clemson, South Carolina USA, 29634
| | - Konstantin G Kornev
- Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina, USA, 29634.
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2
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Wold ES, Aiello B, Harris M, Bin Sikandar U, Lynch J, Gravish N, Sponberg S. Moth resonant mechanics are tuned to wingbeat frequency and energetic demands. Proc Biol Sci 2024; 291:20240317. [PMID: 38920055 DOI: 10.1098/rspb.2024.0317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 05/15/2024] [Indexed: 06/27/2024] Open
Abstract
An insect's wingbeat frequency is a critical determinant of its flight performance and varies by multiple orders of magnitude across Insecta. Despite potential energetic benefits for an insect that matches its wingbeat frequency to its resonant frequency, recent work has shown that moths may operate off their resonant peak. We hypothesized that across species, wingbeat frequency scales with resonance frequency to maintain favourable energetics, but with an offset in species that use frequency modulation as a means of flight control. The moth superfamily Bombycoidea is ideal for testing this hypothesis because their wingbeat frequencies vary across species by an order of magnitude, despite similar morphology and actuation. We used materials testing, high-speed videography and a model of resonant aerodynamics to determine how components of an insect's flight apparatus (stiffness, wing inertia, muscle strain and aerodynamics) vary with wingbeat frequency. We find that the resonant frequency of a moth correlates with wingbeat frequency, but resonance curve shape (described by the Weis-Fogh number) and peak location vary within the clade in a way that corresponds to frequency-dependent biomechanical demands. Our results demonstrate that a suite of adaptations in muscle, exoskeleton and wing drive variation in resonant mechanics, reflecting potential constraints on matching wingbeat and resonant frequencies.
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Affiliation(s)
- Ethan S Wold
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, GA 30332, USA
| | - Brett Aiello
- School of Natural and Health Sciences, Seton Hill University , Greensburg, PA 15601, USA
| | - Manon Harris
- School of Physics, Georgia Institute of Technology , Atlanta, GA 30332, USA
| | - Usama Bin Sikandar
- School of Electrical and Computer Engineering, Georgia Institute of Technology , Atlanta, GA 30332, USA
| | - James Lynch
- Mechanical and Aerospace Engineering, University of California San Diego , San Diego, CA 92161, USA
| | - Nick Gravish
- Mechanical and Aerospace Engineering, University of California San Diego , San Diego, CA 92161, USA
| | - Simon Sponberg
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, GA 30332, USA
- School of Physics, Georgia Institute of Technology , Atlanta, GA 30332, USA
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Stanchak KE, Deora T, Weber AI, Hickner MK, Moalin A, Abdalla L, Daniel TL, Brunton BW. Intraspecific Variation in the Placement of Campaniform Sensilla on the Wings of the Hawkmoth Manduca Sexta. Integr Org Biol 2024; 6:obae007. [PMID: 38715720 PMCID: PMC11074993 DOI: 10.1093/iob/obae007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 01/30/2024] [Accepted: 03/12/2024] [Indexed: 05/15/2024] Open
Abstract
Flight control requires active sensory feedback, and insects have many sensors that help them estimate their current locomotor state, including campaniform sensilla (CS), which are mechanoreceptors that sense strain resulting from deformation of the cuticle. CS on the wing detect bending and torsional forces encountered during flight, providing input to the flight feedback control system. During flight, wings experience complex spatio-temporal strain patterns. Because CS detect only local strain, their placement on the wing is presumably critical for determining the overall representation of wing deformation; however, how these sensilla are distributed across wings is largely unknown. Here, we test the hypothesis that CS are found in stereotyped locations across individuals of Manduca sexta, a hawkmoth. We found that although CS are consistently found on the same veins or in the same regions of the wings, their total number and distribution can vary extensively. This suggests that there is some robustness to variation in sensory feedback in the insect flight control system. The regions where CS are consistently found provide clues to their functional roles, although some patterns might be reflective of developmental processes. Collectively, our results on intraspecific variation in CS placement on insect wings will help reshape our thinking on the utility of mechanosensory feedback for insect flight control and guide further experimental and comparative studies.
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Affiliation(s)
- K E Stanchak
- University of Washington, Department of Biology, Seattle 98195, WA
| | - T Deora
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar Institution of Eminence, Delhi-NCR 201314, India
| | - A I Weber
- University of Washington, Department of Biology, Seattle 98195, WA
| | - M K Hickner
- University of Washington, Department of Mechanical Engineering, Seattle 98195, WA
| | - A Moalin
- University of Washington, Department of Biology, Seattle 98195, WA
| | - L Abdalla
- University of Washington, Department of Biology, Seattle 98195, WA
| | - T L Daniel
- University of Washington, Department of Biology, Seattle 98195, WA
| | - B W Brunton
- University of Washington, Department of Biology, Seattle 98195, WA
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4
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Stanchak KE, Deora T, Weber AI, Hickner MK, Moalin A, Abdalla L, Daniel TL, Brunton BW. Intraspecific variation in the placement of campaniform sensilla on the wings of the hawkmoth Manduca sexta. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.26.546554. [PMID: 37425819 PMCID: PMC10326992 DOI: 10.1101/2023.06.26.546554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Flight control requires active sensory feedback, and insects have many sensors that help them estimate their current locomotor state, including campaniform sensilla, which are mechanoreceptors that sense strain resulting from deformation of the cuticle. Campaniform sensilla on the wing detect bending and torsional forces encountered during flight, providing input to the flight feedback control system. During flight, wings experience complex spatio-temporal strain patterns. Because campaniform sensilla detect only local strain, their placement on the wing is presumably critical for determining the overall representation of wing deformation; however, how these sensilla are distributed across wings is largely unknown. Here, we test the hypothesis that campaniform sensilla are found in stereotyped locations across individuals of Manduca sexta, a hawkmoth. We found that although campaniform sensilla are consistently found on the same veins or in the same regions of the wings, their total number and distribution can vary extensively. This suggests that there is some robustness to variation in sensory feedback in the insect flight control system. The regions where campaniform sensilla are consistently found provide clues to their functional roles, although some patterns might be reflective of developmental processes. Collectively, our results on intraspecific variation in campaniform sensilla placement on insect wings will help reshape our thinking on the utility of mechanosensory feedback for insect flight control and guide further experimental and comparative studies.
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Affiliation(s)
| | - Tanvi Deora
- University of Washington, Department of Biology, Seattle, WA
| | - Alison I Weber
- University of Washington, Department of Biology, Seattle, WA
| | - Michelle K Hickner
- University of Washington, Department of Mechanical Engineering, Seattle, WA
| | - Abna Moalin
- University of Washington, Department of Biology, Seattle, WA
| | - Laila Abdalla
- University of Washington, Department of Biology, Seattle, WA
| | - Thomas L Daniel
- University of Washington, Department of Biology, Seattle, WA
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Wold ES, Lynch J, Gravish N, Sponberg S. Structural damping renders the hawkmoth exoskeleton mechanically insensitive to non-sinusoidal deformations. J R Soc Interface 2023; 20:20230141. [PMID: 37194272 PMCID: PMC10189308 DOI: 10.1098/rsif.2023.0141] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 04/25/2023] [Indexed: 05/18/2023] Open
Abstract
Muscles act through elastic and dissipative elements to mediate movement, which can introduce dissipation and filtering which are important for energetics and control. The high power requirements of flapping flight can be reduced by an insect's exoskeleton, which acts as a spring with frequency-independent material properties under purely sinusoidal deformation. However, this purely sinusoidal dynamic regime does not encompass the asymmetric wing strokes of many insects or non-periodic deformations induced by external perturbations. As such, it remains unknown whether a frequency-independent model applies broadly and what implications it has for control. We used a vibration testing system to measure the mechanical properties of isolated Manduca sexta thoraces under symmetric, asymmetric and band-limited white noise deformations. The asymmetric and white noise conditions represent two types of generalized, multi-frequency deformations that may be encountered during steady-state and perturbed flight. Power savings and dissipation were indistinguishable between symmetric and asymmetric conditions, demonstrating that no additional energy is required to deform the thorax non-sinusoidally. Under white noise conditions, stiffness and damping were invariant with frequency, suggesting that the thorax has no frequency-dependent filtering properties. A simple flat frequency response function fits our measured frequency response. This work demonstrates the potential of materials with frequency-independent damping to simplify motor control by eliminating any velocity-dependent filtering that viscoelastic elements usually impose between muscle and wing.
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Affiliation(s)
- Ethan S. Wold
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - James Lynch
- Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA 92161, USA
| | - Nick Gravish
- Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA 92161, USA
| | - Simon Sponberg
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
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Staton T, Girling RD, Redak RA, Smith SM, Allison JD. Can morphological traits explain species-specific differences in meta-analyses? A case study of forest beetles. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023:e2838. [PMID: 36911981 DOI: 10.1002/eap.2838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 02/08/2023] [Accepted: 02/15/2023] [Indexed: 05/17/2023]
Abstract
Meta-analyses have become a valuable tool with which to synthesize effects across studies, but in ecology and evolution, they are often characterized by high heterogeneity, where effect sizes vary between studies. Much of this heterogeneity can be attributed to species-specific differences in responses to predictor variables. Here, we aimed to incorporate a novel trait-based approach to explain species-specific differences in a meta-analysis by testing the ability of morphological traits to explain why the effectiveness of flight-intercept trap design varies according to beetle species, a critical issue in forest pest management. An existing morphological trait database for forest beetles was supplemented, providing trait data for 97 species, while data from a previous meta-analysis on capture rates of bark or woodboring beetles according to different trap designs were updated. We combined these sources by including nine morphological traits as moderators in meta-analysis models, for five different components of trap design. Traits were selected based on theoretical hypotheses relating to beetle movement, maneuverability, and sensory perception. We compared the performance of morphological traits as moderators versus guild, taxonomic family, and null meta-analysis models. Morphological traits for the effect of trap type (panel vs. multiple-funnel) on beetle capture rates improved model fit (AICc ), reduced within-study variance (σ2 ), and explained more variation (McFadden's pseudo-R2 ) compared with null, guild, and taxonomic family models. For example, morphological trait models explained 10% more of the variance (pseudo-R2 ) when compared with a null model. However, using traits was less informative to explain how detailed elements of trap design such as surface treatment and color influence capture rates. The reduction of within-study variance when accounting for morphological traits demonstrates their potential value for explaining species-specific differences. Morphological traits associated with flight efficiency, maneuverability, and eye size were particularly informative for explaining the effectiveness of trap type. This could lead to improved predictability of optimal trap design according to species. Therefore, morphological traits could be a valuable tool for understanding species-specific differences in community ecology, but other causes of heterogeneity across studies, such as forest type and structure, require further investigation.
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Affiliation(s)
- Tom Staton
- School of Agriculture, Policy and Development, University of Reading, Reading, UK
- Institute of Forestry & Conservation, University of Toronto, Toronto, Ontario, Canada
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, Sault Ste Marie, Ontario, Canada
| | - Robbie D Girling
- School of Agriculture, Policy and Development, University of Reading, Reading, UK
| | - Richard A Redak
- Department of Entomology, University of California Riverside, Riverside, California, USA
| | - Sandy M Smith
- Institute of Forestry & Conservation, University of Toronto, Toronto, Ontario, Canada
| | - Jeremy D Allison
- Institute of Forestry & Conservation, University of Toronto, Toronto, Ontario, Canada
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, Sault Ste Marie, Ontario, Canada
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Rubin JJ, Martin NW, Sieving KE, Kawahara AY. Testing bird-driven diurnal trade-offs of the moon moth's anti-bat tail. Biol Lett 2023; 19:20220428. [PMID: 36722145 PMCID: PMC9890116 DOI: 10.1098/rsbl.2022.0428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 01/09/2023] [Indexed: 02/02/2023] Open
Abstract
Traits are often caught in a dynamic tension of countervailing evolutionary pressures. Trade-offs can be imposed by predators evolutionarily curtailing the conspicuousness of a sexually selected trait, or acting in opposition to another natural selection pressure, for instance, a different predator with a divergent hunting strategy. Some moon moths (Saturniidae) have long hindwing tails that thwart echolocating bat attacks at night, allowing the moth to escape. These long tails may come at a cost, however, if they make the moth's roosting form more conspicuous to visually foraging predators during the day. To test this potential trade-off, we offered wild-caught Carolina wrens (Thryothorus ludovicianus) pastry dough models with real Actias luna wings that were either intact or had tails experimentally removed. We video recorded wrens foraging on models and found that moth models with tails did not experience increased detection and attack by birds. Thus, this elaborate trait, while obvious to human observers, does not seem to come at a cost of increased avian predator attention. The evolution of long hindwing tails, likely driven by echolocating predators at night, does not seem to be limited by opposing diurnal constraints. This study demonstrates the importance of testing presumed trade-offs and provides hypotheses for future testing.
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Affiliation(s)
- Juliette J. Rubin
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
- McGuire Center for Lepidoptera and Biodiversity, Florida museum of Natural History, University of Florida, Gainesville, FL 32611, USA
| | - Nich W. Martin
- Entomology and Nematology Department, University of Florida, Gainesville, FL 32611, USA
| | - Kathryn E. Sieving
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL 32611, USA
| | - Akito Y. Kawahara
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
- McGuire Center for Lepidoptera and Biodiversity, Florida museum of Natural History, University of Florida, Gainesville, FL 32611, USA
- Entomology and Nematology Department, University of Florida, Gainesville, FL 32611, USA
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Abstract
Electromagnetic modelling may be used as a tool for understanding the radar cross section (RCS) of volant animals. Here, we examine this emerging method in detail and delve deeper into the specifics of the modelling process for a single noctuid moth, with the hope of illuminating the importance of different aspects of the process by varying the morphometric and compositional properties of the model. This was accomplished by creating a high-fidelity three-dimensional insect model by micro-CT scanning a gold-palladium-coated insect. Electromagnetic simulations of the insect model were conducted by applying different morphological and compositional configurations using the WiPL-D Pro 3D Electromagnetic Solver. The simulation results show that high-resolution modelling of insects has advantages compared to the simple ellipsoidal models used in previous studies. We find that the inclusion of wings and separating the composition of the body, wings, and legs and antennae have an impact on the resulting RCS of the specimen. Such modifications to the RCS are missed when a prolate spheroid model is used and should not be ignored in future studies. Finally, this methodology has been shown to be useful in exploring the changes in the RCS that result from variations in specimen size. As such, utilising this methodology further for more species will improve the ability to quantitatively interpret aeroecological observations of weather surveillance radars and special-purpose entomological radars.
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Aiello BR, Sikandar UB, Minoguchi H, Bhinderwala B, Hamilton CA, Kawahara AY, Sponberg S. The evolution of two distinct strategies of moth flight. J R Soc Interface 2021; 18:20210632. [PMID: 34847789 DOI: 10.1098/rsif.2021.0632] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Across insects, wing shape and size have undergone dramatic divergence even in closely related sister groups. However, we do not know how morphology changes in tandem with kinematics to support body weight within available power and how the specific force production patterns are linked to differences in behaviour. Hawkmoths and wild silkmoths are diverse sister families with divergent wing morphology. Using three-dimensional kinematics and quasi-steady aerodynamic modelling, we compare the aerodynamics and the contributions of wing shape, size and kinematics in 10 moth species. We find that wing movement also diverges between the clades and underlies two distinct strategies for flight. Hawkmoths use wing kinematics, especially high frequencies, to enhance force and wing morphologies that reduce power. Silkmoths use wing morphology to enhance force, and slow, high-amplitude wingstrokes to reduce power. Both strategies converge on similar aerodynamic power and can support similar body weight ranges. However, inter-clade within-wingstroke force profiles are quite different and linked to the hovering flight of hawkmoths and the bobbing flight of silkmoths. These two moth groups fly more like other, distantly related insects than they do each other, demonstrating the diversity of flapping flight evolution and a rich bioinspired design space for robotic flappers.
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Affiliation(s)
- Brett R Aiello
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.,McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA
| | - Usama Bin Sikandar
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.,Department of Electrical Engineering, Information Technology University, Lahore, Pakistan
| | - Hajime Minoguchi
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | | | - Chris A Hamilton
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, ID 83844, USA
| | - Akito Y Kawahara
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA.,Department of Biology, University of Florida, Gainesville, FL 32608, USA.,Department Entomology and Nematology, University of Florida, Gainesville, FL 32608, USA
| | - Simon Sponberg
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
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