Krugner R, Gordon SD.  2018.  Mating disruption of Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) by playback of vibrational signals in vineyard trellis.  Journal of Pest Management Science.

Krugner R, Gordon SD. 2018. Mating disruption of Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) by playback of vibrational signals in vineyard trellis. Journal of Pest Management Science.

BACKGROUND Glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) is an important vector of the bacterium Xylella fastidiosa, the causal agent of Pierce’s disease of grapevine. Area-wide insecticide applications have suppressed GWSS populations for ca. 25 years, but reduced levels of insecticide susceptibility have been reported. Therefore, alternative methods of control are needed. Objectives of this study were to evaluate efficacy of playback of vibrational mating communication signals for disrupting mating of GWSS in a natural vineyard setting and evaluate spectral properties of signal transmission through vineyard trellis. RESULTS Playback reduced mating of GWSS on grapevines. A total of 28 (out of 134) male-female pairs mated in the control treatment (silence) and only one (out of 134) pair mated when treated with the vibrational signal playback. Playback of vibrational signals through vineyard trellis was affected by distance from signal source, with frequency composition and intensity being the highest at the signal source and lowest on vines positioned away from the source. Frequency composition in canes housing test insects decreased exponentially as distance from the source increased, whereas the relative amplitude of analyzed frequencies decreased linearly. CONCLUSION Although further studies are needed prior to method implementation, data from this study continue to support integration of vibrational mating disruption with current methods to suppress GWSS populations.   Krugner and Gordon.  2018.  Mating disruption of Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) by playback of vibrational signals in vineyard trellis.   Pest Management Science....
Gordon SD. ter Hofstede HM.  2018.  The influence of bat echolocation call duration and timing on auditory encoding of predator distance in noctuoid moths. The Journal of Experimental Biology

Gordon SD. ter Hofstede HM. 2018. The influence of bat echolocation call duration and timing on auditory encoding of predator distance in noctuoid moths. The Journal of Experimental Biology

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 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.   Gordon and ter Hofstede. 2018  The influence of bat echolocation call duration and timing on auditory encoding of predator...
Mazzoni V, Gordon SD, Nieri R, Krugner R.  2017.  Design of a candidate vibrational signal for mating disruption against the glassy-winged sharpshooter, Homalodisca vitripennis, Pest Management Science. 73:2328-2333.

Mazzoni V, Gordon SD, Nieri R, Krugner R. 2017. Design of a candidate vibrational signal for mating disruption against the glassy-winged sharpshooter, Homalodisca vitripennis, Pest Management Science. 73:2328-2333.

The glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, is an important pest of grapevines due to its ability to transmit Xylella fastidiosa, the causal agent of Pierce’s disease. GWSS mating communication is based on vibrational signals; therefore, vibrational mating disruption could be an alternative to insecticides for suppression of GWSS population. Our objectives were to identify spectral features of female signal that elicit male signaling, design disruptive signals able to alter male perception and acceptance of a female, and determine the signal intensity required for future field applications. Results showed that male responses to playback of modified female signals were significantly reduced by 60-75%when part of the female signal spectral components above or below 400 Hz were deleted. Playback bioassays showed that transmission of an 80 Hz pure frequency tone to plants completely suppressed male signaling to female signal playback, even if the disruptive signal amplitude was 10 dB lower than the female signal playback.  Although the mechanism underlying cessation of male signaling activity in the presence of disruption is not yet understood, results suggest that an 80 Hz vibrational signal should be tested in laboratory and field experiments to assess its efficacy in disrupting mating of GWSS Mazzoni V, Gordon SD, Nieri R, Krugner R. 2017. Design of a candidate vibrational signal for mating disruption against the glassy-winged sharpshooter, Homalodisca vitripennis, Pest Management Science....
Gordon SD, Sandoval N, Mazzoni V, Krugner R.  2017.  Mating interference of glassy-winged sharpshooters, Homalodisca vitripennis.  Entomologia Experimentalis et Applicata. 164:27-34

Gordon SD, Sandoval N, Mazzoni V, Krugner R. 2017. Mating interference of glassy-winged sharpshooters, Homalodisca vitripennis. Entomologia Experimentalis et Applicata. 164:27-34

Animal communication is a complex behavior that is influenced by abiotic and biotic factors of the environment.  Glassy-winged sharpshooters (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), primarily use vibrational signaling for courtship communication.  Because GWSS is a major pest, transmitting the plant pathogenic bacterium Xylella fastidiosa, interruption of communication is a possible avenue for control.  Playback of white noise, pre-recorded female signals, and artificial female noise (continuously overlapping female signals) significantly reduced mating of GWSS when compared to silent control mating trials.  Furthermore, to begin to determine the mechanism underlying playback control, female signaling activity was recorded in the presence of stimuli.  In response to playback of female signals, females signaled (duet-like) more often than females tested in the absence of playback.  After the first playback, almost two-thirds of females signaled a response within 3s.  Additionally, one-third of the females signaled within 1s after cessation of white noise, and significantly more in the time periods following noise termination.  Results highlight how GWSS responds to differing competitive disturbances in the environment and lays important ground work that possibly could be used to develop pesticide-free control methods.   Gordon SD, Sandoval N, Mazzoni V, Krugner R. 2017. Mating interference of glassy-winged sharpshooters, Homalodisca vitripennis. Entomologia Experimentalis et Applicata....
Gordon SD, Klenschi E, Windmill JFC.  2017.  Hearing on the fly: the effects of wing position on noctuid moth hearing.  Journal of Experimental Biology. 220:1952-1955

Gordon SD, Klenschi E, Windmill JFC. 2017. Hearing on the fly: the effects of wing position on noctuid moth hearing. Journal of Experimental Biology. 220:1952-1955

The ear of the noctuid moth has only two auditory neurons, A1 and A2, which function in detecting predatory bats. However, the noctuid’s ears are located on the thorax behind the wings. Therefore, since these moths need to hear during flight, it was hypothesized that wing position may affect their hearing. The wing was fixed in three different positions: up, flat, and down. An additional subset of animals was measured with freely moving wings. In order to negate any possible acoustic shadowing or diffractive effects, all wings were snipped, leaving the proximal most portion and the wing hinge intact. Results revealed that wing position plays a factor in threshold sensitivity of the less sensitive auditory neuron A2, but not in the more sensitive neuron A1. Furthermore, when the wing was set in the down position, fewer A1 action potentials were generated prior to the initiation of A2 activity. Analyzing the motion of the tympanal membrane did not reveal differences in movement due to wing position. Therefore, these neural differences due to wing position are proposed to be due to other factors within the animal such as different muscle tensions.   Gordon SD, Klenschi E, Windmill JFC. 2017. Hearing on the fly: the effects of wing position on noctuid moth hearing. Journal of Experimental Biology....
Nieri R, Mazzoni V, Gordon SD, Krugner R.  2017.  Mating behavior and vibrational mimicry in the glassy-winged sharpshooter, Homalodisca vitripennis. Journal of Pest Science. 90:887-889

Nieri R, Mazzoni V, Gordon SD, Krugner R. 2017. Mating behavior and vibrational mimicry in the glassy-winged sharpshooter, Homalodisca vitripennis. Journal of Pest Science. 90:887-889

The glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, is an important vector of Xylella fastidiosa, the causal agent of Pierce’s disease of grapevine. GWSS control relies mainly on insecticides; therefore, an alternative method, such as vibrational mating disruption, is required. However, knowledge of GWSS intraspecific communication is necessary to evaluate applicability of such methods. Mating behavior and associated vibrational signals were described in different social contexts: individuals, pairs, and one female with two competing males. Behavioral analysis showed that GWSS mating communication involved the emission of three male and two female signals, with specific roles in two distinct phases of mating behavior, identification and courtship. Mating success depended on vibrational duets between genders, which were temporarily interrupted in the presence of male rivalry. Male rivalry behavior involved the emission of three distinct rivalry signals. Two rivalry signals resemble female signals and were associated with replacement of the female in the duet by the rival male. The third rivalry signal was emitted by competing males. Data suggested that rival males used mimicry and hostile signals to interrupt the ongoing duet and gain access to a female. In the future, knowledge acquired from this study will be essential to develop a mechanical mating disruption method for GWSS control. Nieri R, Mazzoni V, Gordon SD, Krugner R. 2017. Mating behavior and vibrational mimicry in the glassy-winged sharpshooter, Homalodisca vitripennis. Journal of Pest Science....
Sitvarin M, Gordon SD, Uetz GW, Rypstra A.  2016.  The wolf spider Pardosa milvina detects predator threat level using only vibratory cues.  Behaviour.  153:159-173

Sitvarin M, Gordon SD, Uetz GW, Rypstra A. 2016. The wolf spider Pardosa milvina detects predator threat level using only vibratory cues. Behaviour. 153:159-173

Predators may inadvertently signal their presence and threat level by way of signals in multiple modalities. We used a spider, Pardosa milvina, known to respond adaptively to chemotactile predator cues (i.e., silk, faeces and other excreta) to evaluate whether it could also discriminate predation risk from isolated vibratory cues. Vibrations from its prey, conspecifics, and predators (Tigrosa helluo and Scarites quadriceps) were recorded and played back to Pardosa. In addition, we recorded predator vibrations with and without access to chemotactile cues from Pardosa, indicating the presence of prey. Pardosa did not appear to discriminate between vibrations from prey or conspecifics, but the response to predators depended on the presence of cues from Pardosa. Vibrations from predators with access to chemotactile cues from prey induced reductions in Pardosa activity. Predator cues typically occur in multiple modalities, but prey are capable of imperfectly evaluating predation risk using a limited subset of information. Sitvarin M, Gordon SD, Uetz GW, Rypstra A.  2016.  The wolf spider Pardosa milvina detects predator threat level using only vibratory cues.  Behaviour. ...
Gordon SD, Windmill JFC.  2015.  Hearing ability decreases in ageing locusts.  J. of Experimental Biology.  218:1990-199

Gordon SD, Windmill JFC. 2015. Hearing ability decreases in ageing locusts. J. of Experimental Biology. 218:1990-199

Insects display signs of ageing, despite their short lifespan. However, the limited studies on senescence emphasize longevity or reproduction. We focused on the hearing ability of ageing adult locusts, Schistocerca gregaria. Our results indicate that the youngest adults (2 weeks post-maturity) have a greater overall neurophysiological response to sound, especially for low frequencies (<10 kHz), as well as a shorter latency to this neural response. Interestingly, when measuring displacement of the tympanal membrane that the receptor neurons directly attach to, we found movement is not directly correlated with neural response. Therefore, we suggest the enhanced response in younger animals is due to the condition of their tissues (e.g. elasticity). Secondly, we found the sexes do not have the same responses, particularly at 4 weeks post-adult moult. We propose female reproductive condition reduces their ability to receive sounds. Overall our results indicate older animals, especially females, are less sensitive to sounds. Gordon SD, Windmill JFC. 2015. Hearing ability decreases in ageing locusts. J. of Experimental Biology....
Gordon SD, Jackson JC, Rogers SM, Windmill JFC.  2014.  Listening to the Environment:  Hearing Differences from an Epigenetic Effect in Solitarious and Gregarious Locusts.  Proceedings of the Royal Society B. 281 no. 1795 20141693

Gordon SD, Jackson JC, Rogers SM, Windmill JFC. 2014. Listening to the Environment: Hearing Differences from an Epigenetic Effect in Solitarious and Gregarious Locusts. Proceedings of the Royal Society B. 281 no. 1795 20141693

Locusts display a striking form of phenotypic plasticity, developing into either a lone-living solitarious phase or a swarming gregarious phase depending on population density. The two phases differ extensively in appearance, behaviour, and physiology. We found that solitarious and gregarious locusts have clear differences in their hearing, both in their tympanal and neuronal responses. We identified significant differences in the shape of the tympana that may be responsible for the variations in hearing between locust phases. We measured the nanometre mechanical responses of the ear’s tympanal membrane to sound, finding that solitarious animals exhibit greater displacement. Finally, neural experiments signified that solitarious locusts have a relatively stronger response to high frequencies. The enhanced response to high frequency sounds in the nocturnally flying solitarious locusts suggests greater investment in detecting the ultrasonic echolocation calls of bats, to which they are more vulnerable than diurnally active gregarious locusts. This study highlights the importance of epigenetic effects set forth during development and begins to identify how animals are equipped to match their immediate environmental needs. Gordon SD, Jackson JC, Rogers SM, Windmill JFC.  2014.  Listening to the Environment:  Hearing Differences from an Epigenetic Effect in Solitarious and Gregarious Locusts.  Proceedings of the Royal Society B. 281 no. 1795...
Eberhard MJB*, Gordon SD*, Windmill JFC, Ronacher B.  2014. Temperature effects on the tympanal membrane and auditory receptor neurons in the locust. Journal of Comparative Physiology A.  200:837-847 * These authors contributed equally

Eberhard MJB*, Gordon SD*, Windmill JFC, Ronacher B. 2014. Temperature effects on the tympanal membrane and auditory receptor neurons in the locust. Journal of Comparative Physiology A. 200:837-847 * These authors contributed equally

Poikilothermic animals are affected by variations in environmental temperature, as the basic properties of nerve cells and muscles are altered. Nevertheless, insect sensory systems, such as the auditory system, need to function effectively over a wide range of temperatures, as sudden changes of up to 10 °C or more are common. We investigated the performance of auditory receptor neurons and properties of the tympanal membrane of Locusta migratoria in response to temperature changes. Intracellular recordings of receptors at two temperatures (21 and 28 °C) revealed a moderate increase in spike rate with a mean Q10 of 1.4. With rising temperature, the spike rate–intensity–functions exhibited small decreases in thresholds and expansions of the dynamic range, while spike durations decreased. Tympanal membrane displacement, investigated using microscanning laser vibrometry, exhibited a small temperature effect, with a Q10 of 1.2. These findings suggest that locusts are affected by shifts in temperature at the periphery of the auditory pathway, but the effects on spike rate, sensitivity, and tympanal membrane displacement are small. Robust encoding of acoustic signals by only slightly temperature-dependent receptor neurons and almost temperature-independent tympanal membrane properties might enable locusts and grasshoppers to reliably identify sounds in spite of changes of their body temperature. Eberhard MJB*, Gordon SD*, Windmill JFC, Ronacher B.  2014. Temperature effects on the tympanal membrane and auditory receptor neurons in the locust. Journal of Comparative Physiology A.  200:837-847 * These authors contributed...