Abstract:

【Objective】The objective of this study is to explore the vibration propagation laws of mating calls of the brown planthopper (BPH), Nilaparvata lugens, and to provide the theoretical basis and practical guidance for the development and optimization of novel techniques for physical pest control.【Method】Simulating a paddy field scenario, using the root mean square (RMS) as the measurement index of vibration intensity, the PDV-100 digital laser vibrometer was applied to test and analyze the propagation and attenuation characteristics of vibrations generated by different types of loudspeakers (as vibration sources) in water, air, and on rice plants. Based on the principle of substrate-borne vibration in insects, a steel needle point-touch method was used to play back female mating calls at varying intensities, which aimed to test the response rate of males during their mating active period and determine the range of vibration intensity they could perceive.【Result】When the vibration source was placed in water or air, the vibration intensities of the sinusoidal waves on rice plants decreased with increasing distance within the range of 10 to 500 cm. However, except for the position 10 cm from the vibration source, there was no significant difference in vibration intensity between the two modes at other positions (60-500 cm). At 60 cm, the intensity decreased by 84.87% in water and 73.08% in air compared to that at 10 cm. Furthermore, the application of higher-power directional loudspeakers revealed significantly extended propagation distances of sinusoidal wave signals in the air. Vibration sources with 20 and 30 W output power were attenuated by 87.27% at 15 m and 66.72% at 20 m, respectively. The vibration intensity on rice plants when playing back pre-recorded female and male courtship vibration signals showed no significant difference and increased with the signal strength of the vibration source, following an exponential function relationship. Additionally, the response rate of N. lugens males to female signals of different intensities showed significant differences. When the vibration velocity ranged from 782.2 to 835.9 μm·s^-1, over 83% of male insects exhibited a calling response; however, when the vibration velocity was between 335.2 and 425.4 μm·s^-1 or lower, fewer than 47% of males responded.【Conclusion】The disruptive vibrational signals can propagate to rice plants through the airborne pathway, with greater vibration source intensity resulting in farther propagation distances. The vibration conduction characteristics of rice plants are similar at different growth stages, but rice stems conduct vibrations more effectively than leaves. The results of response tests of N. lugens adults to different vibration intensities can serve as a basis for evaluating the effectiveness of disruptive vibrational signals in controlling N. lugens in the future.

Key words: Nilaparvata lugens, substrate-borne vibration, attenuation law, vibration velocity, physical control