Krugner R, Gordon SD.  In Press.  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. In Press. 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.  In Press.  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. In Press. 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. ...
Uetz GW, Roberts JA, Clark DL, Gibson JS, Gordon SD.  2013.  Active space of multimodal signals of wolf spiders in a complex litter environment.  Behavioral Ecology & Sociobiology. 67:1471-1482

Uetz GW, Roberts JA, Clark DL, Gibson JS, Gordon SD. 2013. Active space of multimodal signals of wolf spiders in a complex litter environment. Behavioral Ecology & Sociobiology. 67:1471-1482

Abstract Multimodal signals may compensate for environmental constraints on communication, as signals in different modalities vary in efficacy. We examined the influence of complex microhabitats on transmission of vibratory and visual signals of courting male Schizocosa ocreata wolf spiders (Araneae: Lycosidae) with laser Doppler vibrometry (LDV) and behavioral observations in lab and field. We measured maximum potential detection distance of visual and vibratory signals by females in laboratory mesocosms, recorded vibration signal attenuation on different substrates, and estimated transmission distances for male vibration signals in the field. We also determined effective line-of sight visual detection distances in the field with laser distance measures. Together, these data were used to estimate the potential and effective active space of multimodal signals. LDV measures show leaves are highly conductive substrates for wolf spider vibratory signals compared to others (soil, wood, rock). For both visual and vibratory modes, lab estimates of maximum potential distance for signal transmission and detection (behavior studies) exceeded estimates of effective active space (signal attenuation, “vanishing point,” and “line-of-sight” measures). Field estimates of transmission distance for signal modes overlap, such that in close range (<20 cm), vibratory signals are more likely to be detected, while farther away, visual signals are more likely to be seen. These findings thus support current  hypotheses regarding how multimodal communication might extend the range of overall signal active space or compensate for environmental constraints. Uetz GW, Roberts JA, Clark DL, Gibson JS, Gordon SD.  2013.  Active space of multimodal signals of wolf spiders in a complex litter environment.  Behavioral Ecology & Sociobiology. 67:1471-1482...
Gordon SD, Uetz GW.  2012.  Environmental interference: impact of acoustic noise on seismic communication and mating success.  Behavioral Ecology. 23:700-714.

Gordon SD, Uetz GW. 2012. Environmental interference: impact of acoustic noise on seismic communication and mating success. Behavioral Ecology. 23:700-714.

Sound is abundant in the environment, often creating ‘‘noise’’ that interferes with animal communication. Animals cope with acoustic interference in a variety of ways, including raising their signal volume (the Lombard effect), changing the pattern, frequency or duration of signals, or changing the time of day when signaling. Although many arthropods use substrate-borne vibration (seismic) signals, the effect of interference from (airborne) acoustic noise on their communication is not well studied. We tested the effects of 3 different types of airborne acoustic sounds on substrate-borne seismic communication and mating success of the ground-dwelling wolf spider, Schizocosa ocreata. We used band-limited white noise (0–4 kHz), predatory bird calls (northern cardinal Cardinalis cardinalis), and a cicada chorus (mixed Magicicada spp.) as interference stimuli. Spider behavior and mating success were differentially affected by each type of environmental acoustic sound. Males took longer to initiate courtship with bird calls, although white noise and cicada calls did not affect male signaling. Females oriented toward males more often with white noise but showed no change in their orientation behavior with bird or cicada calls. Finally, female receptivity and mating success were reduced with white noise and bird calls, whereas cicada calls had no effect. Our data suggest that wolf spiders using seismic vibration in communication respond differently to various types of airborne sounds, transmitted as vibrations, in their environment. This work is among the first to highlight how airborne sounds create seismic interference differentially affecting the behaviors of arthropods living in the leaf litter. Key words: behavioral plasticity, bioacoustics, bird song, cicada, communication, environment, interference, Schizocosa ocreata, sound, vibration, wolf spider. [Behav Ecol]   Gordon...
Gordon SD, Uetz GW.  2011.  Multimodal communication of wolf spiders on different substrates:  evidence for behavioral flexibility.  Animal Behaviour.  81:367-375.

Gordon SD, Uetz GW. 2011. Multimodal communication of wolf spiders on different substrates: evidence for behavioral flexibility. Animal Behaviour. 81:367-375.

Communication in complex environments poses challenges of potential loss of intended messages, but some animals may compensate by using multimodal signalling. Courtship displays of male Schizocosa ocreata (Hentz) wolf spiders are multimodal, consisting of visual and seismic signals. The microhabitat of S. ocreata is complex, including leaf litter, wood/bark, soil and rocks. Results from laser vibrometer measurements in the present study indicated that leaf litter transmitted male courtship signals with greater efficacy. Mating success was significantly greater on leaf litter (∼85%) compared to other substrates (∼30%), even though latency to male courtship did not vary among substrates. Given these results, selection should favour spiders that increase their mating potential on nonconducting substrates. We tested whether spiders detect substrate differences in a choice test, and found that when males and females visited all substrates, they spent significantly more time on leaf litter. We isolated courting male spiders on each substrate and scored courtship behaviours to see whether signals varied with substrate. Males used significantly more visual signals (waves and arches) on substrates that attenuated seismic signals (soil and rocks), but other behaviours showed no differences. Taken together, these results suggest that combined visual/seismic components of multimodal displays may serve as ‘backup signals’, ensuring reception under different environmental conditions. Results also suggest that male S. ocreata have the flexibility to compensate for environmental constraints by seeking microhabitats with more effective vibration conduction properties, and/or by increasing visual signals on substrates where seismic communication is less effective. Gordon SD, Uetz GW.  2011.  Multimodal communication of wolf spiders on different substrates:  evidence for behavioral flexibility.  Animal Behaviour. ...