Krugner and Gordon. 2021. Mating Communication of the Variegated Leafhopper, Erasmoneura variabilis, With Notes on Vibrational Signaling of Other Grapevine Cicadellids in California

by Shira | Jun 6, 2021 |

Leafhoppers in the tribe Erythroneurini are a concern for grape growers in California due to direct feeding damage by piercing the leaves. Management of leafhopper populations in vineyards may be accomplished by insecticide applications, the release of natural enemies, conservation biological control, exploitation of controlled deficit irrigation, or a combination of the above. Based on research on other leafhopper species, a behavioral mating disruption is a viable option, but nothing is known about the mating communication and circadian signaling of these species in vineyards. The objectives of this study were to identify and describe vibrational signals associated with mate selection behavior of Erasmoneura variabilis and Erythroneura ziczac, and evaluate the occurrence of vibrational signals within sympatric populations of E. variabilis, E. ziczac, and Homalodisca vitripennis on grapevines. Analysis of vibrational communication signals revealed that 1) one female signal and two distinct male signals are used in E. variabilis pair formation, 2) the pair formation process in E. variabilis is divided into three communication phases, 3) E. variabilis pre-copulatory communication is longer in the presence than in the absence of male-male rivalry, 4) two distinct signals are used in E. ziczac pair formation, and 5) E. variabilis, E. ziczac, and H. vitripennis sing at night and during the day. Results include detailed descriptions of leafhopper communication signals that are relevant for future development of vibrational disruption as a novel method to suppress populations under field conditions. Krugner R, Gordon SD. 2021. Mating Communication of the Variegated Leafhopper, Erasmoneura variabilis, With Notes on Vibrational Signaling of Other Grapevine Cicadellids in California. Annals of the Entomological Society of America. 114 (4):July 2021, Pages...

Gordon and Krugner 2021. Copulatory Signaling and Polygamy of Glassy-Winged Sharpshooters (Hemiptera: Cicadellidae)

by Shira | May 26, 2021 |

Finding a partner to mate with may be only part of ensuring successful siring of offspring. Females often exhibit cryptic female choice (CFC) during or after copulation, which can influence whose sperm from her multiple partners is chosen for egg fertilization. Known behavioral mechanisms for CFC include assessment of males by their nuptial gifts, duration of copulation, and seminal fluid contents. In this study, the glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), behaviors during the course of copulation were investigated. Glassy-winged sharpshooter (GWSS) use vibrational communication before copulation occurs. However, little is known about behaviors that occur during and after copulation. Results from this study determined that vibrational signaling also occurs during copulation. Vibrational signals similar to those emitted during precopulatory communication were identified during copulation alongside a new, ‘hum-like’ signal that typically occurred within 10 s after the pair joined in copulation. In addition, results determined the duration of copulation was on average of 15 h, though with a 10-h range (8.5–18.5 h) among observed male–female pairs. Finally, both males and females mated more than once. Collectively, results identified key reproductive parameters required for CFC to occur in GWSS. The study expands on the known animals that use CFC and emphasizes the role that copulatory vibrational communication may play setting the foundations for future more in-depth studies. Understanding of insect behaviors necessary for successful production of offspring is important from an ecological perspective and for development of pest control methods.   Gordon SD, Krugner R. 2021. Copulatory Signaling and Polygamy of Glassy-Winged Sharpshooters (Hemiptera: Cicadellidae). Annals of the Entomological Society of America....

Gordon and Krugner. 2019. Mating Disruption by Vibrational Signals: Applications for Management of the Glassy-Winged Sharpshooter. Book Chapter

by Shira | Jan 8, 2020 |

The glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, is a generalist insect and a major pest of grapevines. GWSS is a vector of the bacterium Xylella fastidiosa, causal agent of Pierce’s disease that can lead to grapevine death within few years after infection. This chapter discusses the problem and current GWSS control methods. Then, the focus changes to efforts in developing a novel control method that uses synthetic vibrational signals to disrupt mating and, thus, population growth. A step-by-step method for creating effective playback signals is described and discussed. The method was termed “D.I.E.,” which stands for Describe, Identify, and Execute. The first step is to describe the basic biology of the insect pest with emphasis on communication behaviors. From there, one can begin identifying which candidate signals disrupt communication. Finally, execution tests are conducted to determine which signals effectively disrupt mating in laboratory, and more importantly, in the field. While there are still steps needed for large-scale implementation in the field, the basic biological questions related to whether synthetic vibrational signals can disrupt mating are answered affirmatively. The next direction will be to develop a mechanism of signal transmission across large areas. In addition, season long field trials are needed, taking into consideration natural insect movements into and out of treated areas. Gordon S.D., Krugner R. 2020. Mating Disruption by Vibrational Signals: Applications for Management of the Glassy-Winged Sharpshooter. In: Hill P., Lakes-Harlan R., Mazzoni V., Narins P., Virant-Doberlet M., Wessel A. (eds) Biotremology: Studying Vibrational Behavior. Animal Signals and Communication, vol 6. Springer, Cham. P....

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...