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Cinel SD, Hahn DA, Kawahara AY. Predator-induced stress responses in insects: A review. JOURNAL OF INSECT PHYSIOLOGY 2020; 122:104039. [PMID: 32113954 DOI: 10.1016/j.jinsphys.2020.104039] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 04/26/2018] [Accepted: 02/26/2020] [Indexed: 06/10/2023]
Abstract
Predators can induce extreme stress and profound physiological responses in prey. Insects are the most dominant animal group on Earth and serve as prey for many different predators. Although insects have an extraordinary diversity of anti-predator behavioral and physiological responses, predator-induced stress has not been studied extensively in insects, especially at the molecular level. Here, we review the existing literature on physiological predator-induced stress responses in insects and compare what is known about insect stress to vertebrate stress systems. We conclude that many unrelated insects share a baseline pathway of predator-induced stress responses that we refer to as the octopamine-adipokinetic hormone (OAH) axis. We also present best practices for studying predator-induced stress responses in prey insects. We encourage investigators to compare neurophysiological responses to predator-related stress at the organismal, neurohormonal, tissue, and cellular levels within and across taxonomic groups. Studying stress-response variation between ecological contexts and across taxonomic levels will enable the field to build a holistic understanding of, and distinction between, taxon- and stimulus-specific responses relative to universal stress responses.
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Affiliation(s)
- Scott D Cinel
- Department of Biology, University of Florida, Gainesville, FL 32611, USA; Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA.
| | - Daniel A Hahn
- Department of Entomology & Nematology, University of Florida, Gainesville, FL 32611, USA
| | - Akito Y Kawahara
- Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA
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Cinel SD, Taylor SJ. Prolonged Bat Call Exposure Induces a Broad Transcriptional Response in the Male Fall Armyworm ( Spodoptera frugiperda; Lepidoptera: Noctuidae) Brain. Front Behav Neurosci 2019; 13:36. [PMID: 30863292 PMCID: PMC6399161 DOI: 10.3389/fnbeh.2019.00036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 02/11/2019] [Indexed: 12/22/2022] Open
Abstract
Predation risk induces broad behavioral and physiological responses that have traditionally been considered acute and transitory. However, prolonged or frequent exposure to predators and the sensory cues of their presence they broadcast to the environment impact long-term prey physiology and demographics. Though several studies have assessed acute and chronic stress responses in varied taxa, these attempts have often involved a priori expectations of the molecular pathways involved in physiological responses, such as glucocorticoid pathways and neurohormone production in vertebrates. While relatively little is known about physiological and molecular predator-induced stress in insects, many dramatic insect defensive behaviors have evolved to combat selection by predators. For instance, several moth families, such as Noctuidae, include members equipped with tympanic organs that allow the perception of ultrasonic bat calls and facilitate predation avoidance by eliciting evasive aerial flight maneuvers. In this study, we exposed adult male fall armyworm (Spodoptera frugiperda) moths to recorded ultrasonic bat foraging and attack calls for a prolonged period and constructed a de novo transcriptome based on brain tissue from predator cue-exposed relative to control moths kept in silence. Differential expression analysis revealed that 290 transcripts were highly up- or down-regulated among treatment tissues, with many annotating to noteworthy proteins, including a heat shock protein and an antioxidant enzyme involved in cellular stress. Though nearly 50% of differentially expressed transcripts were unannotated, those that were are implied in a broad range of cellular functions within the insect brain, including neurotransmitter metabolism, ionotropic receptor expression, mitochondrial metabolism, heat shock protein activity, antioxidant enzyme activity, actin cytoskeleton dynamics, chromatin binding, methylation, axonal guidance, cilia development, and several signaling pathways. The five most significantly overrepresented Gene Ontology terms included chromatin binding, macromolecular complex binding, glutamate synthase activity, glutamate metabolic process, and glutamate biosynthetic process. As a first assessment of transcriptional responses to ecologically relevant auditory predator cues in the brain of moth prey, this study lays the foundation for examining the influence of these differentially expressed transcripts on insect behavior, physiology, and life history within the framework of predation risk, as observed in ultrasound-sensitive Lepidoptera and other 'eared' insects.
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Affiliation(s)
- Scott D Cinel
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, IL, United States.,Insect Evolution, Behavior, and Genomics Lab, Florida Museum of Natural History, University of Florida, Gainesville, FL, United States
| | - Steven J Taylor
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, IL, United States.,Colorado College, Colorado Springs, CO, United States
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Thevenon H, Pfuhl G. Discrepancies in the spiking threshold and frequency sensitivity of nocturnal moths explainable by biases in the canonical auditory stimulation method. ROYAL SOCIETY OPEN SCIENCE 2018; 5:172404. [PMID: 29765685 PMCID: PMC5936950 DOI: 10.1098/rsos.172404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 03/12/2018] [Indexed: 06/08/2023]
Abstract
The auditory stimulation method used in experiments on moth A cell(s) is generally believed to be adequate to characterize the encoding of bat echolocation signals. The stimulation method hosts, though, several biases. Their compounded effects can explain a range of discrepancies between the reported electrophysiological recordings and significantly alter the current interpretation. To test the hypothesis that the bias may significantly alter our current understanding of the moth's auditory transducer characteristics, papers using the same auditory stimulation method and reporting on either spiking threshold or spiking activity of the moth's A cells were analysed. The consistency of the reported data was assessed. A range of corrections issued from best practices and theoretical background were applied to the data in an attempt to re-interpret the data. We found that it is not possible to apply a posteriori corrections to all data and bias. However the corrected data indicate that the A cell's spiking may (i) be independent of the repetition rate, (ii) be maximum when detecting long and low-intensity pulses and (iii) steadily reduce as the bat closes on the moth. These observations raise the possibility that a fixed action pattern drives the moths' erratic evasive manoeuvres until the final moment. In-depth investigations of the potential bias also suggest that the auditory transducer's response may be constant for a larger frequency range than thought so far, and provide clues to explain the negative taxis in response to the searching bats' calls detection.
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Gordon SD, Ter Hofstede HM. The influence of bat echolocation call duration and timing on auditory encoding of predator distance in noctuoid moths. ACTA ACUST UNITED AC 2018; 221:221/6/jeb171561. [PMID: 29567831 DOI: 10.1242/jeb.171561] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 01/24/2018] [Indexed: 11/20/2022]
Abstract
Animals co-occur with multiple predators, making sensory systems that can encode information about diverse predators advantageous. Moths in the families Noctuidae and Erebidae have ears with two auditory receptor cells (A1 and A2) used to detect the echolocation calls of predatory bats. Bat communities contain species that vary in echolocation call duration, and the dynamic range of A1 is limited by the duration of sound, suggesting that A1 provides less information about bats with shorter echolocation calls. To test this hypothesis, we obtained intensity-response functions for both receptor cells across many moth species for sound pulse durations representing the range of echolocation call durations produced by bat species in northeastern North America. We found that the threshold and dynamic range of both cells varied with sound pulse duration. The number of A1 action potentials per sound pulse increases linearly with increasing amplitude for long-duration pulses, saturating near the A2 threshold. For short sound pulses, however, A1 saturates with only a few action potentials per pulse at amplitudes far lower than the A2 threshold for both single sound pulses and pulse sequences typical of searching or approaching bats. Neural adaptation was only evident in response to approaching bat sequences at high amplitudes, not search-phase sequences. These results show that, for short echolocation calls, a large range of sound levels cannot be coded by moth auditory receptor activity, resulting in no information about the distance of a bat, although differences in activity between ears might provide information about direction.
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Affiliation(s)
- Shira D Gordon
- Dartmouth College, Department of Biological Sciences, 78 College Street, Hanover, NH 03755, USA
| | - Hannah M Ter Hofstede
- Dartmouth College, Department of Biological Sciences, 78 College Street, Hanover, NH 03755, USA
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Cobo-Cuan A, Kössl M, Mora EC. Hearing diversity in moths confronting a neotropical bat assemblage. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:707-715. [PMID: 28421281 DOI: 10.1007/s00359-017-1170-z] [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: 10/11/2016] [Revised: 02/20/2017] [Accepted: 04/04/2017] [Indexed: 11/30/2022]
Abstract
The tympanal ear is an evolutionary acquisition which helps moths survive predation from bats. The greater diversity of bats and echolocation strategies in the Neotropics compared with temperate zones would be expected to impose different sensory requirements on the neotropical moths. However, even given some variability among moth assemblages, the frequencies of best hearing of moths from different climate zones studied to date have been roughly the same: between 20 and 60 kHz. We have analyzed the auditory characteristics of tympanate moths from Cuba, a neotropical island with high levels of bat diversity and a high incidence of echolocation frequencies above those commonly at the upper limit of moths' hearing sensitivity. Moths of the superfamilies Noctuoidea, Geometroidea and Pyraloidea were examined. Audiograms were determined by non-invasively measuring distortion-product otoacoustic emissions. We also quantified the frequency spectrum of the echolocation sounds to which this moth community is exposed. The hearing ranges of moths in our study showed best frequencies between 36 and 94 kHz. High sensitivity to frequencies above 50 kHz suggests that the auditory sensitivity of moths is suited to the sounds used by sympatric echolocating bat fauna. Biodiversity characterizes predators and prey in the Neotropics, but the bat-moth acoustic interaction keeps spectrally matched.
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Affiliation(s)
- Ariadna Cobo-Cuan
- Research Group in Bioacoustics and Neuroethology, Faculty of Biology, University of Havana, 25 St. 455, Vedado, 10400, Havana, Cuba. .,Department of Integrative Biology and Physiology, University of California Los Angeles, 612 Charles E. Young Drive East, Los Angeles, CA, 90095, USA.
| | - Manfred Kössl
- Institut für Zellbiologie und Neurowissenschaft, J.W. Goethe Universität Frankfurt, Max von Laue Strasse 13, 60438, Frankfurt Am Main, Germany
| | - Emanuel C Mora
- Research Group in Bioacoustics and Neuroethology, Faculty of Biology, University of Havana, 25 St. 455, Vedado, 10400, Havana, Cuba
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Nakano R, Ihara F, Mishiro K, Toyama M, Toda S. High duty cycle pulses suppress orientation flights of crambid moths. JOURNAL OF INSECT PHYSIOLOGY 2015; 83:15-21. [PMID: 26549128 DOI: 10.1016/j.jinsphys.2015.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Revised: 10/23/2015] [Accepted: 11/04/2015] [Indexed: 06/05/2023]
Abstract
Bat-and-moth is a good model system for understanding predator-prey interactions resulting from interspecific coevolution. Night-flying insects have been under predation pressure from echolocating bats for 65Myr, pressuring vulnerable moths to evolve ultrasound detection and evasive maneuvers as counter tactics. Past studies of defensive behaviors against attacking bats have been biased toward noctuoid moth responses to short duration pulses of low-duty-cycle (LDC) bat calls. Depending on the region, however, moths have been exposed to predation pressure from high-duty-cycle (HDC) bats as well. Here, we reveal that long duration pulse of the sympatric HDC bat (e.g., greater horseshoe bat) is easily detected by the auditory nerve of Japanese crambid moths (yellow peach moth and Asian corn borer) and suppress both mate-finding flights of virgin males and host-finding flights of mated females. The hearing sensitivities for the duration of pulse stimuli significantly dropped non-linearly in both the two moth species as the pulse duration shortened. These hearing properties support the energy integrator model; however, the threshold reduction per doubling the duration has slightly larger than those of other moth species hitherto reported. And also, Asian corn borer showed a lower auditory sensitivity and a lower flight suppression to short duration pulse than yellow peach moth did. Therefore, flight disruption of moth might be more frequently achieved by the pulse structure of HDC calls. The combination of long pulses and inter-pulse intervals, which moths can readily continue detecting, will be useful for repelling moth pests.
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Affiliation(s)
- Ryo Nakano
- Breeding and Pest Management Division, NARO Institute of Fruit Tree Science, 2-1 Fujimoto, Tsukuba, Ibaraki 305-8605, Japan; Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada.
| | - Fumio Ihara
- Breeding and Pest Management Division, NARO Institute of Fruit Tree Science, 2-1 Fujimoto, Tsukuba, Ibaraki 305-8605, Japan
| | - Koji Mishiro
- Breeding and Pest Management Division, NARO Institute of Fruit Tree Science, 2-1 Fujimoto, Tsukuba, Ibaraki 305-8605, Japan
| | - Masatoshi Toyama
- Grape and Persimmon Research Division, NARO Institute of Fruit Tree Science, 301-2 Mitsu, Akitsu, Higashi-hiroshima, Hiroshima 739-2494, Japan
| | - Satoshi Toda
- Breeding and Pest Management Division, NARO Institute of Fruit Tree Science, 2-1 Fujimoto, Tsukuba, Ibaraki 305-8605, Japan
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Nakano R, Takanashi T, Surlykke A. Moth hearing and sound communication. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2014; 201:111-21. [DOI: 10.1007/s00359-014-0945-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/13/2014] [Accepted: 09/15/2014] [Indexed: 10/24/2022]
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Clare EL, Goerlitz HR, Drapeau VA, Holderied MW, Adams AM, Nagel J, Dumont ER, Hebert PDN, Brock Fenton M. Trophic niche flexibility inGlossophaga soricina: how a nectar seeker sneaks an insect snack. Funct Ecol 2013. [DOI: 10.1111/1365-2435.12192] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Elizabeth L. Clare
- School of Biological Sciences University of Bristol Woodland RoadBristol BS8 IUG UK
| | - Holger R. Goerlitz
- School of Biological Sciences University of Bristol Woodland RoadBristol BS8 IUG UK
- Max Planck Institute for Ornithology Sensory Ecology Group Eberhard‐Gwinner‐Straße Seewiesen 82319 Germany
| | - Violaine A. Drapeau
- School of Biological Sciences University of Bristol Woodland RoadBristol BS8 IUG UK
| | - Marc W. Holderied
- School of Biological Sciences University of Bristol Woodland RoadBristol BS8 IUG UK
| | - Amanda M. Adams
- Department of Biology Western University 1151 Richmond StreetLondon ON Canada N6A 5B7
| | - Juliet Nagel
- Center For Environmental Science Appalachian Laboratory University of Maryland 301 Braddock RoadFrostburg MD21532 USA
| | - Elizabeth R. Dumont
- Department of Biology University of Massachusetts 221 Morrill Science Center, 611 N Pleasant St Amherst MA01002 USA
| | - Paul D. N. Hebert
- Department of Integrative Biology Biodiversity Institute of Ontario University of Guelph Guelph ONCanada N1G 2W1
| | - M. Brock Fenton
- Department of Biology Western University 1151 Richmond StreetLondon ON Canada N6A 5B7
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Mora EC, Cobo-Cuan A, Macías-Escrivá F, Pérez M, Nowotny M, Kössl M. Mechanical tuning of the moth ear: distortion-product otoacoustic emissions and tympanal vibrations. J Exp Biol 2013; 216:3863-72. [PMID: 23868848 DOI: 10.1242/jeb.085902] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mechanical tuning of the ear in the moth Empyreuma pugione was investigated by distortion-product otoacoustic emissions (DPOAE) and laser Doppler vibrometry (LDV). DPOAE audiograms were assessed using a novel protocol that may be advantageous for non-invasive auditory studies in insects. To evoke DPOAE, two-tone stimuli within frequency and level ranges that generated a large matrix of values (960 frequency-level combinations) were used to examine the acoustic space in which the moth tympanum shows its best mechanical and acoustical responses. The DPOAE tuning curve derived from the response matrix resembles that obtained previously by electrophysiology, and is V-shaped and tuned to frequencies between 25 and 45 kHz with low Q10dB values of 1.21±0.26. In addition, while using a comparable stimulation regime, mechanical distortion in the displacement of the moth's tympanal membrane at the stigma was recorded with a laser Doppler vibrometer. The corresponding mechanical vibration audiograms were compared with DPOAE audiograms. Both types of audiograms have comparable shape, but most of the mechanical response fields are shifted towards lower frequencies. We showed for the first time in moths that DPOAE have a pronounced analogy in the vibration of the tympanic membrane where they may originate. Our work supports previous studies that point to the stigma (and the internally associated transduction machinery) as an important place of sound amplification in the moth ear, but also suggests a complex mechanical role for the rest of the transparent zone.
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Affiliation(s)
- Emanuel C Mora
- Research Group in Bioacoustics and Neuroethology, Department of Animal and Human Biology, Faculty of Biology, Havana University, 25 St. No. 455, Vedado, CP. 10400, Havana, Cuba
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ter Hofstede HM, Goerlitz HR, Ratcliffe JM, Holderied MW, Surlykke A. The simple ears of noctuoid moths are tuned to the calls of their sympatric bat community. J Exp Biol 2013; 216:3954-62. [DOI: 10.1242/jeb.093294] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary
Insects with bat-detecting ears are ideal animals for investigating sensory system adaptations to predator cues. Noctuid moths have two auditory receptors (A1 and A2) sensitive to the ultrasonic echolocation calls of insectivorous bats. Larger moths are detected at greater distances by bats than smaller moths. Larger moths also have lower A1 best thresholds, allowing them to detect bats at greater distances and possibly compensating for their increased conspicuousness. Interestingly, the sound frequency at the lowest threshold is lower in larger than smaller moths, suggesting that the relationship between threshold and size might vary across frequencies used by different bat species. Here, we demonstrate that the relationships between threshold and size in moths were only significant at some frequencies, and these frequencies differed between three locations (UK, Canada, Denmark). The relationships were more likely to be significant at call frequencies used by proportionately more bat species in the moths’ specific bat community, suggesting an association between the tuning of moth ears and the cues provided by sympatric predators. Additionally, we found that the best threshold and best frequency of the less sensitive A2 receptor are also related to size, and that these relationships hold when controlling for evolutionary relationships. The slopes of best threshold vs. size differ, however, such that the difference in threshold between A1 and A2 is greater for larger than smaller moths. The shorter time from A1 to A2 excitation in smaller than larger moths could potentially compensate for shorter absolute detection distances in smaller moths.
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Affiliation(s)
| | - Holger R. Goerlitz
- University of Bristol, UK; Max Planck Institute for Ornithology, Germany
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