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.

by Shira | Mar 30, 2018 |

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

by Shira | Feb 2, 2018 |

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.

by Shira | May 19, 2017 |

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

by Shira | Apr 11, 2017 |

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

by Shira | Mar 21, 2017 |

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....