Intensity of vibrational signals determines mating behaviour in Scaphoideus titanus Ball (Hemiptera: Cicadellidae)

Insects use different signal modalities to communicate with their conspecifics. Substrate-borne vibrations are widely used among those communicating with mechanical signals. We studied the role of signal intensity for the mating behaviour in Scaphoideus titanus, a vibrational communicating leafhopper that is a vector of the lethal phytoplasma grapevine disease Flavescence dorée. As males called for the females and the substrate velocity (intensity) measured at the dominant frequency of the female replies was in the range 0.0005 - 0.001 mm/s, males either walked around randomly and emitted long, irregular identification signals, or performed call-fly behaviour, by jumping off the plant after a female reply. When males perceived female signals over 0.001 mm/s they started searching while performing a location duet. Only when male and female were on the same leaf, courtship duets were recorded with intensities over 0.01 mm/s. These results show that S. titanus males may adjust their behavioural strategies to localize conspecific partners according to signal intensity.