The reproductive strategy and the vibrational duet of the leafhopper Empoasca vitis

Abstract

The recent description of a new vibrational mating disruption method to control the leafhopper Scaphoideus titanus Ball opened questions about its possible application to other leafhopper pests. Since the prerequisite for the method's successful application is a deep knowledge of the species mating behavior and the exact role of associated signals, we conducted behavioral assays on the green leafhopper Empoasca vitis Göthe, a pest of grapevine and other crops in Europe and Asia. Laser vibrometer recordings of single and paired individuals (male and female) during a 24-h period enabled us to detect and describe 2 male and 1 female signal. The pair formation starts when the female replies to a male call and a duet is established, then it continues through 2 different behavioral stages: Location and Courtship. The proper courtship begins only when the male locates the female. The latter is characterized by a significant change in temporal parameters that regards both the signals and the duet structure. Although the male calling activity and the female replying rate were the same during the 24 h, a lower number of matings was recorded during the night. We discuss the possible role of vision and of the species ecology as factors of reproductive success and mating strategy. Our conclusion is that the mechanical mating disruption technique seems feasible for future application to this species.

Vibrational mating disruption of Empoasca vitis by natural or artificial disturbance noises

“…Our results and the studies of H. vitripennis and Pentatomidae suggest that the replying gender, which tunes its response strictly with the calling signal, is more affected by external noises in that the noise impairs the perception of the call, thus reducing the ability to reply within the proper time window. Conversely, the callers do not stop calling because they do not rely on a vibrational trigger to initiate signaling . Interestingly, E. vitis females reacted differently to different DN playbacks.…”

“…An explanation of this difference in gender reaction to disruptive signals seems to be linked to gender roles in the mating duet. In E. vitis , males call spontaneously and continue to call and change position until they perceive a female's reply; by contrast females do not signal unless they perceive a male call . This may explain why males are less likely to be affected by natural or artificial external noises, while females cease replying to male calls soon after the introduction of external noises.…”

“…To prevent insects from escaping, both the leaf and the mini shaker were placed into a plastic cube (20 × 20 × 20 cm) with a hole on the top for the laser beam. Individuals were allowed to acclimatize on the leaf for 3 min before females were stimulated with male calls following the protocol for female stimulation by Nieri and Mazzoni . The female's response to the playback stimulated the male to establish a duet with the female.…”

“…E. vitis vibrational signals were named according to Nieri and Mazzoni . Newly described signals were named according to the behavioral context.…”

“…the call‐fly strategy) while waiting for the reply of a receptive female. When a female replies, a duet is established that ensures that the male locates the female for mating success . During the duet, the male and female alternate MCs and female replies (FRs).…”