Use of noise generators to inhibit mating of leafhoppers

Leafhoppers (Hemiptera Cicadellidae), notoriously include many important insect pests which use species-specific substrate-borne vibrations as mating signals to estimate identity and to perform location and courtship, after establishing a vibrational duet with the partner. Scaphoideus titanus is a grapevine pest, vector of the phytoplasma disease “Flavescence dorée”. In this species rival males show complex rivalry behaviour which includes the emission of a specific disturbance noise to interrupt a mating duet of another couple. Our hypothesis was that by playing back the disturbance noise into grapevine plants we would have been able to disrupt the mating behaviour of S. titanus, thus preventing the copulation. Our experiments of mating disruption started in 2008 and followed 5 steps. 1) Description of the mating behaviour of S. titanus and the vibrational signals associated to the phases preceding the copula (Fig.1). 2) Laboratory tests on pairs placed on a grapevine leaf to demonstrate that mating disruption with vibrational signals was feasible. 3) We tested a system of potted plants inside plastic cages interconnected by iron wires, to simulate a vineyard trellis. Virgin pairs of S. titanus were released into the cages for 18 hrs (4 pm to 10 am) and a first prototype of a vibrational shaker was used to vibrate the wire. As a result more than 90% of pairs remained unmated (in control treatment only 20% of pairs did not mate). 4) We applied vibrational mating disruption to mature plants in an open vineyard. Pairs of virgin males and females were released inside net sleeves including 3-4 grapevine shoots with fully developed 8-12 leaves. Again the disruption signal, generated by a specific device, was continuously applied to plants through the supporting trellis wire for 18 hrs. Results showed that even 10 m away from the source more than 90% of pairs remained unmated, compared to 20% of non-mated pair in controls . 5) We applied the method to test new prototypes of vibrating device that may be effective at longer distances and with different disruption time regimes in order to spare energy consumption. We found that 65% of mating disruption is still achieved at 45m and that at least 18 hrs of disruption are necessary to have 80% of success. Now our aim is to further optimize the system in order to: (1) make the device more effective for control of S. titanus and other leafhoppers; (2) make it an economically sustainable tool for agricultural use; (3) to set pilot and demo tests in commercial farms starting from 2015.