A ten year research on vibrational communication in Scaphoideus titanus: science fiction or future prospect?

Scaphoideus titanus Ball (Hemiptera: Cicadellidae) is a feared nearctic univoltine leafhopper, vector of Flavescence dorée phytoplasma (FD) in European vineyards. In this insect pair formation and mating are mediated by substrate-borne vibrational signals. Males call spontaneously, carrying out a specific “call and fly” behavior followed by a well-structured courtship song. Females emit signals only in response to males. Rival males compete for mating, producing a disruptive noise (DN) aimed at interrupting a duet in place between pairs. Concurrently with the first description of this behavior, which took place at the Third European Hemiptera Congress (St. Petersburg 2004), we started thinking about how to utilize this knowledge in practice. The first step was to speculate on the use of a playback of the male DN in laboratory tests to prevent copula. The extremely positive results obtained stimulated us to take a step forward, testing a system of potted plants in plastic cages interconnected by a iron wire to simulate a vineyard trellis. A vibrational shaker prototype provided by industry (CBC Europe Milan Branch) was applied to the wire and used to transfer DN to the plants. Virgin males and females were repeatedly released in the cages for the time of the experiment (18 hours). In this way, about 90% of pairs were disrupted up to 10 meters away from the shaker, whereas 80% of pairs mated in the not-vibrated control plants. Similar positive results were obtained by applying the system, with approximately same materials and methods, on plants of a vineyard. A further experiment, which is currently in progress, included the use of a new prototype of shaker designed to transfer DN to longer distances along the row while keeping the efficiency and the lowest possible power consumption. This is an important requirement by industry, which is concerned with developing and putting in the market an economically feasible device. In this test we found that 65% of mating disruption is still possible at 45 meters and 18 h of shaker operation are necessary to get success in 80% of cases. Some bottlenecks that have recently emerged in the field application (i.e. a reduction in system efficiency with the increase of the plant weight during the process of development and maturation of the grapes) make us think that further improvements of the device are required. Nevertheless, we very much hope that the results of this research, recently published in 5 international entomological Journals, not only affected our personal scientific rating but could represent - with the collaboration of the entire scientific community and an increasing involvement of industry - a hint for the implementation of a future system of ‘low impact’ pest control.