Design of a candidate vibrational signal for mating disruption against the glassy-winged sharpshooter, Homalodisca Vitripennis

Authors: MAZZONI, VALERIO - Fondazione Edmund Mach; Gordon, Shira; NIERI, RACHELE - Fondazione Edmund Mach; Krugner, Rodrigo

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2017
Publication Date: 5/19/2017
Citation: Mazzoni, V., Gordon, S.D., Nieri, R., Krugner, R. 2017. Design of a candidate vibrational signal for mating disruption against the glassy-winged sharpshooter, Homalodisca Vitripennis. Pest Management Science. doi: 10.1002/ps.4618.

Interpretive Summary: Pierce’s disease is an economically important problem in grape growing regions of the southern U.S. Pierce’s disease is caused by Xylella fastidiosa, a bacterium transmitted from plant to plant by insect vectors, including the glassy-winged sharpshooter, Homalodisca vitripennis. For this species to thrive in crops, males and females must communicate using vibrational signals transmitted through the plant. Vibrational signals of glassy-winged sharpshooter include harmonic frequencies starting around 80 Hz and repeating every 100 Hz creating at least 10 harmonics (over 1 kHz). Manipulation of natural signals with deletions from the signal spectrum to reduce harmonic repeats resulted in a lower male response rate to a female call. Furthermore, adding an 80 Hz pure tone signal to plants while glassy-winged sharpshooters were trying to communicate suppressed male signaling. Therefore, an 80 Hz pure tone frequency signal may be a candidate noise to use for disruption of glassy-winged sharpshooter communication on grapevines. The implication of these results is that if insect communication can be disrupted with a pure tone, then mating will not occur. If there is no mating, females will not become fertilized and population growth will be reduced.

Technical Abstract: 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 GWSS populations’ suppression. The 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 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 fully understood, results suggest that an 80 Hz vibrational signal should be tested in laboratory and field experiments to assess efficacy in disrupting mating of GWSS.