|NIERI, RACHELE - Fondazione Edmund Mach
|MAZZONI, VALERIO - Fondazione Edmund Mach
Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 11/10/2015
Publication Date: 12/10/2015
Citation: Krugner, R., Nieri, R., Gordon, S.D., Mazzoni, V. 2015. Substrate-borne vibrational signals in intraspecific communication of glassy-winged sharpshooters (GWSS). In: Research Progress Reports, Pierce's Disease and Other Designatred Pests and Diseases of Wine Grapes, California Department of Food and Agriculture, December, 2015, Sacramento, California. p. 104-109.
Interpretive Summary: Leafhoppers and sharpshooters communicate via vibrational signals transmitted through the plant. Signals are very low frequency and intensity “sound” waves that could be the key to a novel control method that may be incorporated in an integrated management strategy. A laser-Doppler vibrometer is being used to identify and describe signals used by glassy-winged sharpshooter (GWSS) to communicate. GWSS uses signals in intra- and inter-gender communication with specific signals required to achieve mating. Bioassays using paired virgin males and females on plants revealed that GWSS males search for females on plants while females wait for males to approach. Visual signals, physical contact, and specific vibrational signals are used by GWSS to establish male and female hierarchy and preferential access to mates. However, GWSS females also can be “choosy”, suggesting that both intrasexual (male-male combat) and intersexual (mate choice) selections may occur. While GWSS rivalry calls negatively impact courtship behaviors, it is not known if the overall reproductive success of individuals can be artificially affected by signal playbacks. Since what they “say” to each other has a big effect on behaviors, signals may be exploited as an attractant, repellent, and/or disruptive signal which could be a useful, non-chemical control method for suppressing GWSS populations. Can these sounds be reproduced to manipulate GWSS behaviors? The answer is: Yes. In the laboratory, mini-shakers and speakers deliver pre-recorded natural sounds or synthetic sounds to plants through a trellis wire thereby artificially stimulating individuals to produce natural responses to playback signals. In preliminary trials, communication (duets, trios, and quartets) with GWSS males and females has been established using pre-recorded calls. The ability to establish a communication channel and elicit GWSS response to select signals represents an important step towards the next goal: identification of signals capable of influencing GWSS behavior for disruption of mating.
Technical Abstract: Exploitation of vibrational signals for suppressing glassy-winged sharpshooter (GWSS) populations could prove to be a useful tool. However, existing knowledge on GWSS vibrational communication is insufficient to implement a management program for this pest in California. Therefore, the objective of this study is to identify and describe substrate-borne signals associated with intraspecific communication of GWSS. Recordings of males and females placed together on plants revealed a complex series of behaviors linked to vibrational signals that lead to mating. Male-female GWSS communication can be divided into three stages: 1) duet, 2) courtship and location, and 3) precopula. In Stage 1, females initiated the duet in 15 of 21 cases. The female can modulate its signal in length and in structure. Analysis of the call structure across the different stages of communication revealed that the length of female call (FC) was shorter in stage 3 (average 0.70 ± 0.49 s, n=8) than in other stages. In addition, the dominant frequency of FC reduced from 93 to 68 Hz. Similarly, the dominant frequency of male calls reduced from 100 to 89 Hz between stages 1 and 2. Data are currently being analyzed to characterize the spectral and temporal features of signals such as frequency span, dominant and/or fundamental frequency, intensity, and pulse repetition rate.