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Yager DD. Predator detection and evasion by flying insects. Curr Opin Neurobiol 2012; 22:201-7. [PMID: 22226428 DOI: 10.1016/j.conb.2011.12.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 12/12/2011] [Accepted: 12/17/2011] [Indexed: 11/29/2022]
Abstract
Echolocating bats detect prey using ultrasonic pulses, and many nocturnally flying insects effectively detect and evade these predators through sensitive ultrasonic hearing. Many eared insects can use the intensity of the predator-generated ultrasound and the stereotyped progression of bat echolocation pulse rate to assess risk level. Effective responses can vary from gentle turns away from the threat (low risk) to sudden random flight and dives (highest risk). Recent research with eared moths shows that males will balance immediate bat predation risk against reproductive opportunity as judged by the strength and quality of conspecific pheromones present. Ultrasound exposure may, in fact, bias such decisions for up to 24 hours through plasticity in the CNS olfactory system. However, brain processing of ultrasonic stimuli to yield adaptive prey behaviors remains largely unstudied, so possible mechanisms are not known.
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Affiliation(s)
- David D Yager
- Department of Psychology and Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD 20742, United States.
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YAGER DAVIDD, SVENSON GAVINJ. Patterns of praying mantis auditory system evolution based on morphological, molecular, neurophysiological, and behavioural data. Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.2008.00996.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Triblehorn JD, Ghose K, Bohn K, Moss CF, Yager DD. Free-flight encounters between praying mantids (Parasphendale agrionina) and bats (Eptesicus fuscus). J Exp Biol 2008; 211:555-62. [DOI: 10.1242/jeb.005736] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYThrough staged free-flight encounters between echolocating bats and praying mantids, we examined the effectiveness of two potential predator-evasion behaviors mediated by different sensory modalities: (1) power dive responses triggered by bat echolocation detected by the mantis ultrasound-sensitive auditory system, and (2) `last-ditch' maneuvers triggered by bat-generated wind detected by the mantis cercal system. Hearing mantids escaped more often than deafened mantids (76% vs 34%, respectively; hearing conveyed 42%advantage). Hearing mantis escape rates decreased when bat attack sequences contained very rapid increases in pulse repetition rates (escape rates <40%for transition slopes >16 p.p.s. 10 ms–1; escape rates>60% for transition slopes <16 p.p.s. 10 ms–1). This suggests that echolocation attack sequences containing very rapid transitions(>16 p.p.s. 10 ms–1) could circumvent mantis/insect auditory defenses. However, echolocation attack sequences containing such transitions occurred in only 15% of the trials. Since mantis ultrasound-mediated responses are not 100% effective, cercal-mediated evasive behaviors triggered by bat-generated wind could be beneficial as a backup/secondary system. Although deafened mantids with functioning cerci did not escape more often than deafened mantids with deactivated cerci (35%vs 32%, respectively), bats dropped mantids with functioning cerci twice as frequently as mantids with deactivated cerci. This latter result was not statistically reliable due to small sample sizes, since this study was not designed to fully evaluate this result. It is an interesting observation that warrants further investigation, however, especially since these dropped mantids always survived the encounter.
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Affiliation(s)
- J. D. Triblehorn
- Department of Psychology, University of Maryland, College Park, MD 20742,USA
| | - K. Ghose
- Department of Psychology, University of Maryland, College Park, MD 20742,USA
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD 20742, USA
| | - K. Bohn
- Department of Psychology, University of Maryland, College Park, MD 20742,USA
| | - C. F. Moss
- Department of Psychology, University of Maryland, College Park, MD 20742,USA
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD 20742, USA
- Institute for Systems Research, University of Maryland, College Park, MD 20742, USA
| | - D. D. Yager
- Department of Psychology, University of Maryland, College Park, MD 20742,USA
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD 20742, USA
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Stumpner A, Molina J. Diversity of intersegmental auditory neurons in a bush cricket. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2006; 192:1359-76. [PMID: 16964494 DOI: 10.1007/s00359-006-0164-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2006] [Revised: 07/04/2006] [Accepted: 08/18/2006] [Indexed: 11/29/2022]
Abstract
Various auditory interneurons of the duetting bush cricket Ancistrura nigrovittata with axons ascending to the brain are presented. In this species, more intersegmental sound-activated neurons have been identified than in any other bush cricket so far, among them a new type of ascending neuron with posterior soma in the prothoracic ganglion (AN4). These interneurons show not only morphological differences in the prothoracic ganglion and the brain, but also respond differently to carrier frequencies, intensity and direction. As a set of neurons, they show graded differences for all of these parameters. A response type not described among intersegmental neurons of crickets and other bush crickets so far is found in the AN3 neuron with a tonic response, broad frequency tuning and little directional dependence. All neurons, with the exception of AN3, respond in a relatively similar manner to the temporal patterns of the male song: phasically to high syllable repetitions and rhythmically to low syllable repetitions. The strongest coupling to the temporal pattern is found in TN1. In contrast to behavior the neuronal responses depend little on syllable duration. AN4, AN5 and TN1 respond well to the female song. AN4 (at higher intensities) and TN1 respond well to a complete duet.
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Affiliation(s)
- Andreas Stumpner
- Johann-Friedrich-Blumenbach-Institut für Zoologie und Anthropologie Abt. Neurobiologie, Berliner Str. 28, 37073 Göttingen, Germany.
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Triblehorn JD, Yager DD. Wind generated by an attacking bat: anemometric measurements and detection by the praying mantis cercal system. J Exp Biol 2006; 209:1430-40. [PMID: 16574803 DOI: 10.1242/jeb.02132] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYThe wind-sensitive cercal system, well-known for mediating terrestrial escape responses, may also mediate insect aerial bat-avoidance responses triggered by wind generated by the approaching bat. One crucial question is whether enough time exists between detection and capture for the insect to perform a successful evasive maneuver. A previous study estimated this time to be 16 ms, based on cockroach behavioral latencies and a prediction for the detection time derived from a simulated predator moving toward a simulated prey. However, the detection time may be underestimated since both the simulated predator and prey lacked certain characteristics present in the natural situation. In the present study, actual detection times are measured by recording from wind-sensitive interneurons of a tethered praying mantis that serves as the target for a flying, attacking bat. Furthermore, using hot-wire anemometry, we describe and quantify the wind generated by an attacking bat. Anemometer measurements revealed that the velocity of the bat-generated wind consistently peaks early with a high acceleration component(an important parameter for triggering wind-mediated terrestrial responses). The physiological recordings determined that the mantis cercal system detected an approaching bat 74 ms before contact, which would provide the insect with 36 ms to perform a maneuver before capture. This should be sufficient time for the mantis to respond. Although it probably would not have time for a full response that completely evades the bat, even a partial response might alter the mantid's trajectory enough to cause the bat to mishandle the insect,allowing it to escape.
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Triblehorn JD, Yager DD. Timing of praying mantis evasive responses during simulated bat attack sequences. J Exp Biol 2005; 208:1867-76. [PMID: 15879067 DOI: 10.1242/jeb.01565] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYPraying mantids perform evasive maneuvers that vary with the level of danger posed by their bat predators. The vocalization pattern of attacking bats provides cues that mantids can potentially use to decide how and when to respond. Using pulse trains simulating bat attack echolocation sequences, this study determines when in the attack sequence the mantis power dive (its response to high-level threat) occurs and predicts the parameters within the echolocation sequence that are important for eliciting the response. For sequences with a rapid transition from low to high pulse repetition rates(PRRs), the evasive response occurred close to the point during the simulated sequence when the bat would have contacted the mantis. However, the evasive response occurred earlier if the transition was gradual. Regardless of the transition type, the prediction data show that sequences trigger the response when PRRs reach 20-40 pulses s-1. These results suggest that a bat gradually increasing its PRR could `tip off' the mantis, enabling it to escape. Attack sequences contain gradual transitions when bats engage in strobing behavior, an echolocation phenomenon that may help the bat perceive the auditory scene. Conversely, bat attack sequences that contain rapid increases in PRR close to the point of capture could circumvent the mantid's auditory defense. Based on these findings, mantids as well as other insects could benefit from having a back-up defense response to offset any advantage the bat gains by rapidly switching from low to high PRRs.
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Fullard JH, Ratcliffe JM, Guignion C. Sensory ecology of predator-prey interactions: responses of the AN2 interneuron in the field cricket, Teleogryllus oceanicus to the echolocation calls of sympatric bats. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2005; 191:605-18. [PMID: 15886992 DOI: 10.1007/s00359-005-0610-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2004] [Revised: 01/19/2005] [Accepted: 01/28/2005] [Indexed: 10/25/2022]
Abstract
We observed the responses of the AN2 interneuron in the Pacific field cricket, Teleogryllus oceanicus, a cell implicated in eliciting avoidance flight away from bats, to acoustic stimuli representing the echolocation calls of bats as well as field recordings of search and gleaning attack calls of six species of insectivorous sympatric bats (West Australia, Australia: Tadarida australis, Chalinolobus goudii, Nyctophilus geoffroyi; Queensland, Australia: Vespadelus pumilus, Myotis adversus; Kaua'i, Hawai'i: Lasiurus cinereus). The broad frequency sensitivity of the AN2 cell indicates that T. oceanicus has evolved to detect a wide range of echolocation call frequencies. The reduced sensitivity of this cell at frequencies higher than 70 kHz suggests that some bats (e.g., the gleaning species, N. geoffroyi) may circumvent this insect's auditory defences by using frequency-mismatched (allotonic) calls. The calls of the freetail bat, T. australis evoked the strongest response in the AN2 cell but, ironically, this may allow this bat to prey upon T. oceanicus as previous studies report that under certain conditions, flying crickets exhibit ambiguous directional responses towards frequencies similar to those emitted by this bat. Short duration calls (1--2 ms) are sufficient to evoke AN2 responses with instantaneous spike periods capable of causing defensive flight behaviours; most bats tested emit calls of durations greater than this. The short calls of N. geoffroyi produced during gleaning attacks may reduce this species' acoustic conspicuousness to this cricket.
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Affiliation(s)
- James H Fullard
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada L5L 1C6.
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Abstract
This study identifies the cuticular metathoracic structures in earless cockroaches that are the homologs to the peripheral auditory components in their sister taxon, praying mantids, and defines the nature of the cuticular transition from earless to eared in the Dictyoptera. The single, midline ear of mantids comprises an auditory chamber with complex walls that contain the tympana and chordotonal transduction elements. The corresponding area in cockroaches, between the furcasternum and coxae, has many socketed hairs arranged in discrete fields and the Nerve 7 chordotonal organ, the homolog of the mantis tympanal organ. The Nerve 7 chordotonal organ attaches at the apex of the lateral ventropleurite (LVp), which has the same shape and general structure as an auditory chamber wall. High-speed video shows that when the coxa moves toward the midline, the LVp rotates medially to stimulate socketed hairs, and also moves like a triangular hinge giving the chordotonal organ maximal in-out stimulation. Formation of the mantis auditory chamber from the LVp and adjacent structures would involve only enlargement, a shift toward the midline, and a mild rotation. Almost all proprioceptive function would be lost, which may constitute the major cost of building and maintaining the mantis ear. Isolation from leg movement dictates the position of the mantis ear in the midline and the rigid frame, formed by the cuticular knobs, which protects the chordotonal organs.
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Affiliation(s)
- David D Yager
- Department of Psychology and Neuroscience, Cognitive Science Program, University of Maryland, College Park, Maryland 20742, USA.
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Fullard JH, Dawson JW, Jacobs DS. Auditory encoding during the last moment of a moth's life. J Exp Biol 2003; 206:281-94. [PMID: 12477898 DOI: 10.1242/jeb.00085] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The simple auditory system of noctuoid moths has long been a model for anti-predator studies in neuroethology, although these ears have rarely been experimentally stimulated by the sounds they would encounter from naturally attacking bats. We exposed the ears of five noctuoid moth species to the pre-recorded echolocation calls of an attacking bat (Eptesicus fuscus) to observe the acoustic encoding of the receptors at this critical time in their defensive behaviour. The B cell is a non-tympanal receptor common to all moths that has been suggested to respond to sound, but we found no evidence of this and suggest that its acoustic responsiveness is an artifact arising from its proprioceptive function. The A1 cell, the most sensitive tympanal receptor in noctuid and arctiid moths and the only auditory receptor in notodontid moths, encodes the attack calls with a bursting firing pattern to a point approximately 150 ms from when the bat would have captured the moth. At this point, the firing of the A1 cell reduces to a non-bursting pattern with longer inter-spike periods, suggesting that the moth may no longer express the erratic flight used to escape very close bats. This may be simply due to the absence of selection pressure on moths for auditory tracking of bat echolocation calls beyond this point. Alternatively, the reduced firing may be due to the acoustic characteristics of attack calls in the terminal phase and an acoustic maneuver used by the bat to facilitate its capture of the moth. Although the role of less sensitive A2 cell remains uncertain in the evasive flight responses of moths it may act as a trigger in eliciting sound production, a close-range anti-bat behaviour in the tiger moth, Cycnia tenera.
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Affiliation(s)
- James H Fullard
- Department of Biology, Erindale College, University of Toronto, 3359 Mississauga Road, Mississauga, Ontario Canada L5L 1C6.
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